U.S. patent application number 17/319945 was filed with the patent office on 2021-11-18 for systems and methods for improving safety and resilience of electric circuits and electric grid infrastructure.
The applicant listed for this patent is GoPlug, LLC. Invention is credited to George Betak, Donald J. Christian, John J. Matranga.
Application Number | 20210359515 17/319945 |
Document ID | / |
Family ID | 1000005654324 |
Filed Date | 2021-11-18 |
United States Patent
Application |
20210359515 |
Kind Code |
A1 |
Betak; George ; et
al. |
November 18, 2021 |
SYSTEMS AND METHODS FOR IMPROVING SAFETY AND RESILIENCE OF ELECTRIC
CIRCUITS AND ELECTRIC GRID INFRASTRUCTURE
Abstract
An apparatus and methods are disclosed for monitoring the
operation of an electrical power-transfer system and detecting and
handling hazardous and undesirable system states. In accordance
with one embodiment, an electrical signal is injected into the
electrical power-transfer system. During or after the injection of
the electrical signal, the following arc measured, (1) an
electrical property between a first sensor and a second sensor to
obtain a first measurement, (2) the electrical property between the
second sensor and a third sensor to obtain a second measurement,
and (3) the electrical properly between the first sensor and the
third sensor to obtain a third measurement. The electrical
power-transfer system is determined to be in a hazardous state
based on the first measurement, the second measurement, and the
third measurement, and in response to the determination one or more
actions are performed to correct the hazardous state.
Inventors: |
Betak; George; (Milpitas,
CA) ; Christian; Donald J.; (Fremont, CA) ;
Matranga; John J.; (Moraga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GoPlug, LLC |
Fremont |
CA |
US |
|
|
Family ID: |
1000005654324 |
Appl. No.: |
17/319945 |
Filed: |
May 13, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63024659 |
May 14, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 3/0012 20200101;
H02J 13/00002 20200101; G05B 9/02 20130101 |
International
Class: |
H02J 3/00 20060101
H02J003/00; H02J 13/00 20060101 H02J013/00; G05B 9/02 20060101
G05B009/02 |
Claims
1. A method comprising: injecting an electrical signal into an
electrical power-transfer system, wherein the electrical
power-transfer system comprises an electrical power source, an
electrical load, a first sensor, a second sensor, a third sensor, a
first conductor, a second conductor, and a third conductor, and
wherein the first sensor is electrically coupled to the second
sensor and the first conductor, and wherein the second sensor is
electrically coupled to the third sensor and the second conductor,
and wherein the third sensor is electrically coupled to the third
conductor; measuring, during or after the injection of the
electrical signal, (1) an electrical property between the first
sensor and the second sensor to obtain a first measurement, (2) the
electrical property between the second sensor and the third sensor
to obtain a second measurement, and (3) the electrical property
between the first sensor and the third sensor to obtain a third
measurement; determining that the electrical power-transfer system
is in a hazardous state based on the first measurement, the second
measurement, and the third measurement; and in response to the
determining that the electrical power-transfer system is in the
hazardous state, performing one or more actions to correct the
hazardous state.
2. The method of claim 1 wherein the electrical property is
impedance.
3. The method of claim 1 further comprising identifying the first
conductor as a cause of the hazardous state based on at least one
of the first measurement, the second measurement, or the third
measurement.
4. The method of claim 1 wherein the electrical signal is injected
between the first sensor and the second sensor.
5. The method of claim 1 wherein the electrical signal is injected
in response to a signal transmitted to the electrical power
source.
6. The method of claim 5 wherein the signal is transmitted to the
electrical power source by an electrical monitoring device that
further receives measurements from the first sensor.
7. The method of claim 1 wherein the one or more actions comprises
modulating current in the electrical power-transfer system.
8. The method of claim 7 wherein the modulating fails to correct
the hazardous state, and wherein the one or more actions further
comprises a shutoff of power, and wherein the shutoff is in
response to the modulating failing to correct the hazardous
state.
9. A method comprising: injecting a first electrical signal into an
electrical power-transfer system, wherein the electrical
power-transfer system comprises an electrical power source, an
electrical load, a first sensor, a second sensor, a third sensor, a
first conductor, a second conductor, and a third conductor, and
wherein the first sensor is electrically coupled to the second
sensor and the first conductor, and wherein the second sensor is
electrically coupled to the third sensor and the second conductor,
and wherein the third sensor is electrically coupled to the third
conductor; measuring, during or after the injection of the first
electrical signal, an electrical property between the first sensor
and the second sensor to obtain a first measurement; injecting a
second electrical signal into the electrical power-transfer system;
measuring, during or after the infection of the second electrical
signal, the electrical property between the second sensor and the
third sensor to obtain a second measurement; determining that the
electrical power-transfer system is in a hazardous state based on
the first measurement and the second measurement; and in response
to the determining that the electrical power-transfer system is in
the hazardous state, performing one or more actions to correct the
hazardous state.
10. The method of claim 9 wherein the electrical property is DC
resistance.
11. The method of claim 9 wherein the first electrical signal is a
continuous signal.
12. The method of claim 9 further comprising selecting one of the
first conductor, the second conductor, or the third conductor as a
cause of the hazardous state as on at least one of the first
measurement or the second measurement.
13. The method of claim 9 wherein the first electrical signal is
injected between the first sensor and the second sensor, and
wherein the second electrical signal is injected between the second
sensor and the third sensor.
14. The method of claim 9 wherein the one or more actions comprises
modulating current in the electrical power-transfer system.
15. The method of claim 14 wherein the modulating fails to correct
the hazardous state, and wherein the one or more actions further
comprises a shutoff of power, and wherein the shutoff is in
response to the modulating failing to correct the hazardous
state.
16. The method of claim 9 further comprising estimating a rate of
corrosion based on the first measurement and the second
measurement.
17. A method for detecting and handling a suboptimal state of an
electrical power-transfer system, wherein the electrical
power-transfer system comprises an electrical power source, an
electrical load, a first sensor, a second sensor, a third sensor, a
first conductor, a second conductor, and a third conductor, and
wherein the first sensor is electrically coupled to the second
sensor and the first conductor, and wherein the second sensor is
electrically coupled to the third sensor and the second conductor,
and wherein the third sensor is electrically coupled to the third
conductor, and wherein the method comprises: measuring, by the
first sensor, an environmental property to obtain a first
measurement; measuring, by the second sensor, the environmental
property to obtain a second measurement; measuring, by the third
sensor, the environmental property to obtain a third measurement;
determining that the electrical power-transfer system is in the
suboptimal state based on the first measurement, the second
measurement, and the third measurement; identifying a proper subset
of the first conductor, the second conductor, and the third
conductor as a cause of the suboptimal state; and in response to
the determining that the electrical power-transfer system is in the
suboptimal state, performing one or more actions to correct the
suboptimal state.
18. The method of claim 17 wherein the suboptimal state is one or
overload or underload.
19. The method of claim 17 wherein the environmental property is
one of temperature, humidity, or pressure.
20. The method of claim 17 wherein the one or more actions
comprises modulating current in the electrical power-transfer
system.
Description
STATEMENT OF RELATED APPLICATIONS
[0001] The present application claims priority to, and incorporates
fully by reference, U.S. Provisional Patent Application No.
63/024,659 filed May 14, 2020.
FIELD OF THE INVENTION
[0002] The present disclosure relates to electrical power-transfer
systems.
BACKGROUND OF THE INVENTION
[0003] Electrical power-transfer systems are capable of supplying
power to and charging devices such as smartphones, electrical
vehicle (EV) chargers, etc. Such systems may possess defects and/or
develop faults that pose safety hazards, potentially leading to
fires, electrocution, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 depicts a block diagram of a system comprising an
electrical source, an electrical load, and a power-transfer
monitoring device, in accordance with one embodiment of the present
disclosure.
[0005] FIG. 2 depicts a block diagram of sensor array 125-i, as
shown in FIG. 1, in accordance with one embodiment of the present
disclosure.
[0006] FIG. 3 depicts a block diagram of environmental sensors
230-i, as shown in in FIG. 2, in accordance with one embodiment of
the present disclosure.
[0007] FIG. 4 depicts an example installation of power-transfer
monitoring device 110, as shown in FIG. 1, in accordance with one
embodiment of the present disclosure.
[0008] FIG. 5 depicts a flow diagram of aspects of a method for
detecting and handling a hazardous state of an electrical
power-transfer system, in accordance with one embodiment of the
present disclosure.
[0009] FIG. 6 depicts a flow diagram of aspects of a method for
detecting and handling an undesirable state of an electrical
power-transfer system, in accordance with one embodiment of the
present disclosure.
[0010] FIG. 7 depicts an example impulse response characteristic in
accordance with one embodiment of the present disclosure.
[0011] FIG. 8 depicts an example of a typical diurnal pattern for
temperature in accordance with one embodiment of the present
disclosure.
[0012] FIG. 9 depicts an example of a power-transfer cycle during a
service session in which an electrical load is connected to an
electrical power-transfer system, power is transferred to or
consumed by the electrical load during the connection, and the
electrical load is subsequently disconnected, in accordance with
one embodiment of the present disclosure.
DETAILED DESCRIPTION
[0013] Embodiments of the present disclosure are capable of
monitoring the operation of an electrical power-transfer system and
detecting undesirable and hazardous states of the system. For the
purposes of this disclosure, the term "electrical power-transfer
system" is defined as an apparatus comprising one or more
electrical sources and one or more conductors connected to a
power-consuming load. (For convenience and brevity, "electrical
power-transfer system" may sometimes be referred to simply as a
"power-transfer system").
[0014] For the purposes of this disclosure, the term "hazardous
state" of an electrical power-transfer system is a state in which
one or both of: (1) the system is unsafe as a result of an
event-in-progress or an event that has already occurred (e.g., a
fire, an earthquake, etc.); and (2) the system has a vulnerability
that makes the electrical power-transfer system susceptible to
unsafe events. It should be noted that the event triggering the
hazardous state might by caused by the system itself (e.g., a fire
resulting from conductor corrosion, etc.), or might be an external
event (e.g., an earthquake, a flood, etc.). Embodiments of the
present disclosure therefore can provide early warnings of future
unsafe events.
[0015] For the purposes of this disclosure, the term "defect" is
defined as a pre-existing flaw. In particular, a defect in a
power-transfer system is defined as a flaw in one or more elements
of the system (e.g., a conductor, insulation, etc.) that may be
present prior to operation of the system. Defects may be due, for
example, to defective product materials; product manufacturing
defects (e.g., missing strands in a conductor, loose wire strands,
improper coiling, improperly-sized conductor crimp,
improperly-sized insulation crimp, improper strip length, improper
wire insertion, excessive terminal bending, improper crimp
positioning, improperly-sized bellmouth, improper carrier cut-off
length, bent lock tangs, incomplete lock tangs, misaligned lock
tangs, conductive dust, crimp contamination prior to use, corrosion
prior to use, interference with connector mating ["terminal
butting"], loose fastener screws, incomplete fastener encirclement,
etc.); damage from handling and/or installation (e.g., nicks,
strand twist damage, bending stress damage, kink damage, etc.); and
so forth.
[0016] For the purposes of this disclosure, the term "fault" is
defined as a flaw that arises during operation of a system, either
spontaneously or developing over time. Faults in a power-transfer
system may arise, for example, as a result of abrasion, vibration,
wear, operational stress, component aging, changing environmental
conditions, animal chewing, corrosion (e.g., due to moisture, salt,
degradation of an interface between dissimilar metals, etc.),
sparking, high-energy charges, overcurrent, magnetic susceptibility
(e.g., current leakage paths and short circuits due to metallic
ferrous particles, etc.), overheating, seasonal environmental
stress, diurnal environmental stress, and so forth.
[0017] In some instances, defects/faults in a power-transfer system
may be hidden or inaccessible. For example, a defect/fault may be
buried underground, embedded in concrete work, located behind a
wall, located under a floor, located above a ceiling panel, and so
forth. These defects/faults may be exposed by particular events,
such as power surges, changing environmental conditions, etc.
[0018] Improvements to electrical distribution systems have been
made in recent years, including the deployment of
ground-fault-circuit-interrupters (GFCIs) and current monitoring
transformers paired with current-limiting circuitry. These
improvements, however, still fail to guard against failure modes
such as latent and time-varying latent hazards. These failure modes
were once rare but have become more prevalent with the
proliferation of modern mobile appliances that are frequently
recharged at high current levels. Mobile appliances are transported
between locations and may be connected opportunistically or
haphazardly to well-worn connectors. This has made the new failures
mode much more common. The higher frequency has increased the
probability of occurrence and therefore increased the risk of this
hazard class.
[0019] A system may appear safe, but the connection of novel
devices with new operating characteristics may violate the safe
operating envelope without warning, with unanticipated
consequences. Further, modern mobile appliances can present dynamic
and often dramatic shift in power demand. A case in point is
electric vehicles whose appetite for power can exceed the capacity
for most fixed electrical systems. In this case, the devices nearly
always challenge the upper capacity limits of the stationary
infrastructure to which they connect.
[0020] FIG. 1 depicts a block diagram of an electrical
power-transfer system 100, in accordance with one embodiment of the
present disclosure. As shown in the figure, electrical
power-transfer system 100 comprises a power-transfer monitoring
device 110 that is inserted between an electrical source 170 (e.g.,
a battery, a solar array, a connection to a utility grid, a
distribution panel, etc.) and a power-consuming electrical load 190
with battery storage (e.g., an EV charger, etc.), thereby forming a
conducting path electrical source 170->power-transfer monitoring
device 110->electrical load 190 that transfers power from
electrical source 170 to electrical load 190, thereby "charging"
electrical load 190. In one embodiment, electrical source 170
comprises a branch circuit that is protected by a circuit
breaker.
[0021] In one example, electrical source 170 is stationary and
electrical load 190 is a mobile appliance (e.g., a mobile
electrical vehicle [EV], a lawn mower, a wheelchair, etc.) that can
be connected to and disconnected from power-transfer monitoring
device 110, or, when power-transfer monitoring device 110 is not
present, can be connected to and disconnected from electrical
source 170. Electrical load 190 is a consumer of electric power,
and typically incorporates storage for future use when disconnected
from the electrical source. As will be appreciated by those skilled
in the art, in some embodiments electrical source 170 might supply
power via alternating current (AC), while in some other embodiments
electrical source 170 might supply power via direct current
(DC).
[0022] In some embodiments, electrical load 190 is capable of
protecting its internal battery by either accepting charging
current or by blocking power. Admittance (charging) or rejection
(non-charging) is accomplished with a built-in power conversion
device or a BMS (Battery Management System), which are incorporated
in some electrical loads for safety, longevity, and
self-protection. In AC power systems, the power admittance involves
a conversion from AC (incoming line) to DC (for battery energy
storage). With modern converters, the rate of power conversion is
controllable or "dispatchable."
[0023] Electrical power-transfer system 100 further comprises a
status device 150 that is capable of receiving signals from
processor 130 indicating the operational status of the system,
thereby facilitating diagnostic operations. In some
implementations, the signals may also be used for setup and
parametric adjustment of installation-specific parameters (e.g.,
electrical properties such as operating voltage; system capacity;
response time; AC or DC operation, etc.), as well as for
specification of environmental operating characteristics (for
example, at the time of installation).
[0024] In some examples, status device 150 might be a display
(e.g., a text display, a graphical user interface (GUI)
touchscreen, etc.), while in other examples status device 150 might
be an on/off indicator light, while in still other examples status
device 150 might be some other type of transducer such as a
speaker, while in yet other examples status device 150 might be a
wireless or wireline conduit (e.g., a Wi-Fi base station, etc.)
that can connect to a smartphone or other type of device. In one
embodiment, communication between processor 130 and 150 is via a
serial-interface data communication line.
[0025] As shown in FIG. 1, power-transfer monitoring device 110
comprises landing points 120-1, 120-2, and 120-3, sensor arrays
125-1, 125-2, and 125-3, processor 130, memory 131, clock 132, and
transceiver 140, interconnected as shown. The landing points 120-1,
120-2, and 120-3 are connected to electrical source 170 via
respective conductors 180-1, 180-2 and 180-3, and are connected to
electrical load 190 via respective conductors 185-1, 185-2 and
185-3. The points provide mechanical stability and an
electro/acoustic/thermal conductive reference. In some embodiments,
landing points 120-1, 120-2, and 120-3 might be
electrically-conductive terminals, while in some other embodiments
landing points 120-1, 120-2, and 120-3 might be mechanically
clamped or crimped on to conductors 180/185, while in yet other
embodiments landing points 120-1, 120-2, and 120-3 might be
connected to conductors 180/185 via a combination of these
techniques (for example, landing point 120-1 is an
electrically-conductive terminal, landing point 120-2 is
mechanically clamped to conductors 180-2 and 185-2, and landing
point 120-3 is mechanically crimped to conductors 180-3 and
185-3.
[0026] In some embodiments conductors 180 might be solid wires,
while in some other embodiments conductors 180 might be stranded
wires, while in still other embodiments conductors 180 might be
something else (e.g., cables, bus bars, printed circuit traces,
etc.). In some embodiments, conductors 180-1/180-2/180-3 might be
uniform in type (e.g., all three conductors are solid wires, all
three conductors are stranded wires, etc.), while in some other
embodiments conductors 180-1/180-2/180-3 might vary in type (e.g.,
two of the conductors solid wires and one conductor stranded wire;
one conductor a solid wire, one conductor a stranded wire, and one
conductor a cable; etc.). In addition, in some embodiments
conductors 180-1/180-2/180-3 might be insulated, while in some
other embodiments conductors 180-1/180-2/180-3 might be
uninsulated, while in still other embodiments, one or two of the
conductors might be insulated and the remaining conductor(s)
uninsulated.
[0027] Landing points 120 are further connected to electrical load
190 via conductors 185-1, 185-2 and 185-3, which deliver power to
electrical load 190. Conductors 185-1, 185-2 and 185-3, like
conductors 180-1, 180-2 and 180-3, may be solid wires, stranded
wires, cables, bus bars, printed circuit traces, etc. In some
embodiments, conductors 185-1/185-2/185-3 might be of the same
type, while in other embodiments conductors 185-1/185-2/185-3 might
vary in type. In addition, in some embodiments conductors
185-1/185-2/185-3 might be insulated, while in some other
embodiments conductors 185-1/185-2/185-3 might be uninsulated,
while in still other embodiments, one or two of the conductors
might be insulated and the remaining conductor(s) uninsulated.
[0028] In some examples, a conductor 180-i might comprise a
plurality of conducting segments joined via one or more junction
points (e.g., a safety box that contains a splice, a busbar, a
branch connection point, etc.). In some such instances the segments
might be of the same type (e.g., all are solid wires, etc.), while
in other instances the segments might vary in type. Similarly, in
some instances the number and type of segments might be the same
for all three conductors 180, 180-2 and 180-3, while in other
instances the number of segments might vary, or the type of
segments might vary, or both.
[0029] In some examples, a conductor 185-i might , like conductor
180-i, comprise a plurality of conducting segments joined via one
or more junction points. In some such examples the segments might
be of the same type (e.g., all are solid wires, etc.), while in
other instances the segments might vary in type. Similarly, in some
examples the number and type of segments might be the same for all
three conductors 185-1, 185-2 and 185-3, while in other instances
the number of segments might vary, or the type of segments might
vary, or both. The above examples may be true, for example, when
one or more connectors and/or one or more plug receptacles are
present.
[0030] In some examples, each conductor 185-i might be of the same
composition as respective conductor 180-i, while in other examples,
one or more of the conductors 185 might be of a different type than
respective conductor(s) 180. Further, in some embodiments
conductors 185-1, 185-2 and 185-3 might be insulated, while in some
other embodiments conductors 185-1, 185-2 and 185-3 might be
uninsulated, while in still other embodiments, one or two of the
conductors might be insulated with the remaining conductor(s)
uninsulated.
[0031] In one embodiment, conductors 180-1 and 185-1 are positive
(or "hot") conductors, conductors 180-2 and 185-2 are negative (or
"return") conductors, and conductors 180-3 and 185-3 are neutral
reference (or "safety earth") conductors. It should be noted that
some other embodiments might use only two conducting paths, rather
than three conductive paths (i.e., two landing points 120-1 and
120-2, respective sensor arrays 125-1 and 125-2, and respective
conductors 180-1/185-1 and 180-2/185-2). This might be a viable
option for certain low-cost or non-critical applications, however a
two-conductor arrangement is generally less desirable. In
particular, such systems will not comply with modern safety codes,
and have reduced perceptive capability that may reduce system
performance. In addition, redundancy, which is beneficial for
self-calibration and self-test purposes, in reduced in
two-conductor systems compared to three-conductor systems.
[0032] It should further be noted that some other embodiments might
use four conducting paths rather than three (e.g., for a
three-phase circuit, etc.). Such embodiments could comprise four
landing points 120-1, 120-2, 120-3 and 120-4, respective sensor
arrays 125-1, 125-2, 125-3 and 125-4, and respective conductors
180-1/185-1, 180-2/185-2, 180-3/185-3, and 180-4/185-4.
[0033] Each sensor array 125-i is capable of obtaining measurement
data pertaining to one or more parameters (for example, one or more
values of one or more measured properties; a function of one or
more values of one or more measured properties, such as a rounding
function, an averaging function, a differential over time [e.g., a
high-pass filter, etc.]; and so forth), and is further capable of
providing these data to processor 130. In one embodiment, sensor
arrays 125 are integrated circuits that communicate with processor
130 via a shared serial bus. The composition of sensor arrays 125
and their associated parameters in one embodiment are described in
detail below with respect to FIGS. 2 and 3.
[0034] Processor 130 is capable of receiving data from sensor
arrays 125 and performing the methods of FIGS. 5 and 6 described
below. In one embodiment, processor 130 is a special-purpose
processing device such as a digital signal processing (DSP)
microcontroller, an application specific integrated circuit (ASIC),
a field programmable gate array (FPGA), or the like. In some other
embodiments, processor 130 may be a general-purpose processing
device, such as a microprocessor, central processing unit, or the
like. More particularly, processor 130 may be a complex instruction
set computing (CISC) microprocessor, a reduced instruction set
computing (RISC) microprocessor, a very long instruction word
(VLIW) microprocessor, a processor implementing other instruction
sets or combinations of instruction sets, or the like. Such
processors may execute instructions stored in memory 131, including
instructions corresponding to one or more blocks of the methods of
FIGS. 7 through 13 described below, read data from memory 131,
and/or write data to memory 131. It should be noted that while a
single processor is depicted in FIG. 1, in some other embodiments
power-transfer monitoring device 110 might comprise a plurality of
processors.
[0035] Memory 131 stores data and executable instructions,
including instructions and data corresponding to the methods of
FIGS. 7 through 13 described below, and may include volatile memory
devices (e.g., random access memory [RAM]), non-volatile memory
devices (e.g., flash memory), and/or other types of memory devices.
Clock 132 transmits the current time, date, and day of the week to
processor 130 in well-known fashion.
[0036] In one embodiment, power-transfer monitoring device 110
comprises a printed circuit board on to which landing points 120,
sensor arrays 125 and processor 130 are mounted. In some examples,
each landing point 120-i is a conductive printed pad comprising a
two-dimensional clad plate that is soldered to sensor array 125-i
and/or processor 130. Materials such as fiberglass, polyester,
polymide, etc. may be used to provide thermal insulation by which
isolation and sensory independence between sensor arrays 125-1,
125-2, and 125-3 are maintained.
[0037] In one embodiment, processor 130 is capable of transmitting
data signals and control signals to electrical source 170 and is
further capable of receiving signals from electrical source 170, as
indicated in FIG. 1. In one implementation, signals between
processor 130 and electrical source are transmitted/received via a
serial-interface data communication line. It should be noted that
in some other embodiments, signals may be transmitted in one
direction only, from processor 130 to electrical source 170.
[0038] In one example, the control signals are ON/OFF binary
signals capable of controlling a safety relay of electrical source
170, and of interrupting power delivery by electrical source 170.
As described in detail below, data signals may include status
information pertaining to safety, performance, carrying capacity,
availability, etc. Operational status may be reported as a stream
of data updates and may include, for example, instantaneous system
performance, safety status, voltage, frequency, current, ampacity,
availability, time, historical events with time-stamps, and so
forth. The status reported may describe one of several states--for
example, system available, system unavailable, system idle, system
in use, system reserved, or system out-of-service with diagnostic
subcode for maintenance purposes. This status may change over time
as the system goes through repeated cycles of use.
[0039] Under normal safe operating conditions, processor 130
transmits a control signal that instructs electrical source 170 to
continue supplying power. When a potentially-hazardous condition is
detected, processor 130 instead transmits a control signal (e.g.,
an exception flag, etc.) that instructs electrical source 170 to
modulate, temporarily interrupt, or completely shut off the flow of
power, as appropriate, based on the particular condition. In some
implementations this functionality may be provided by an
interruptive solid-state switch circuit breaker, which can be
tripped OFF (e.g., by injecting a tiny leakage current into the
breaker's leak-detection or GFCI circuit., etc.). In some other
implementations, a relay contactor, voltage control, or current
control may be employed.
[0040] In one embodiment, processor 130 is further capable of
transmitting data signals and control signals to electrical load
190. In one example, data signals transmitted to electrical load
190 may, like the data signals transmitted to electrical source
170, include status information pertaining to safety, performance,
carrying capacity, availability, etc. Under normal safe operating
conditions, the signals will indicate whether or not electrical
load 190 has permission to continue drawing power (e.g., "OK to
Charge", "Do Not Charge Now", etc.). In one embodiment, the signals
may also control the rate of power transfer (e.g., maximum, 25%
reduction, 50% reduction, etc.), as well as timing (e.g., scheduled
delays, periodic power transfer, etc.).
[0041] In some implementations, communications between processor
130 and electrical load 190 are via a serial-interface data
communication line that is also capable of detecting and announcing
when electrical load 190 has been disconnected, and when some other
electrical load has been connected. In some other implementations,
an analog proportional interface or a pulse width modulation (PLM)
time-based signal may be employed in lieu of a serial
interface.
[0042] Transceiver 140 is capable of receiving signals from one or
more devices (e.g., a personal computer, a server, a wireless base
station, an off-board GPS receiver, etc.), and forwarding to
processor 130 data encoded in these signals (e.g., location-related
data, time-related data, ambient characteristic data, etc.).
Transceiver 140 is further capable of receiving data from processor
130, encoding the data in signals and transmitting the signals
(e.g., transmitting sensor data to a remote computer system that
performs monitoring, etc.)
[0043] In some embodiments, transceiver 140 may communicate with
devices via wireless signals (e.g., RF signals, etc.), while in
some other embodiments transceiver 140 may communicate via wireline
signals (e.g., Ethernet, etc.), while in still other embodiments
transceiver 140 may employ a plurality of communication
technologies and/or protocols (for example, Wi-Fi, Bluetooth,
Ethernet, and CDMA). It will be appreciated by those skilled in the
art that in the latter case, monitoring device may comprise a
plurality of transceivers rather than a single transceiver. For
convenience, however, this disclosure will simply refer to
transceiver 140, regardless of whether monitoring device comprises
a single transceiver or a plurality of transceivers.
[0044] In some embodiments, sensor arrays 125-1/125-2/125-3 might
have the same set of sensors, while in some other embodiments,
sensor arrays 125-1/125-2/125-3 might have different sets of
sensors (e.g., the set of sensors for one sensor array is a proper
subset of the sensors of another sensor array; the set of sensors
for one sensor array is a proper subset of the sensors of another
sensor array, augmented with one or more additional sensors not
depicted in FIGS. 2 and 3; the set of sensors for one sensor array
and the set of sensors for another sensor array are disjoint;
etc.).
[0045] In accordance with some embodiments, the three sensor arrays
might be uniform in attitude, while in some other embodiments, they
may vary in attitude. For example, when the sensor arrays comprise
optical sensors, which may have sensitive surfaces, it might be
advantageous to orient the sensor arrays at different angles,
particular when they have narrow cones and/or limited focus (e.g.,
one up, one left, and one right; etc.). Similarly, in some
embodiments the three sensor arrays might be uniform in
environmental properties such as bandwidth, wavelength etc.), while
in some other embodiments they may have different environments. As
will be appreciated by those skilled in in the art, the particular
choice of attitudes/environments might be made in order to bring
out a particular quality that is relevant to the application (e.g.,
bandwidth, center frequency, etc.).
[0046] In addition, some embodiments may employ insulation and/or
isolation between the sensor arrays. In the case of optical
sensors, for example, opaque material might be placed in between
the sensors, while for acoustic and/or vibration sensors,
mechanical insulation and/or isolation might be employed, while for
magnetic sensors, a magnetic shield (e.g., mumetal, etc.) might be
employed.
[0047] In some embodiments, electrical power-transfer system 100
may have the capability to reverse the flow of power (a "two-way
system"), so that electrical load 190 can be discharged during
particular time intervals in addition to being charged during other
time intervals. During discharge, power flows out of electrical
load 190 toward electrical source 170, thereby driving electrical
source 170. Discharge may be useful, for example, during a power
outage when electrical source 170 becomes disconnected from its
power supply. For the case where electrical load 190 is an
electrical vehicle, this discharge is sometimes referred to as
"V2G". In one embodiment, the operation of power-transfer
monitoring device 110 is unaffected by the direction of power flow,
functioning in the same manner and equally well in both directions
(e.g., in charging and discharging modes, etc.).
[0048] FIG. 2 depicts a block diagram of sensor array 125-i, as
shown in FIG. 1, in accordance with one embodiment of the present
disclosure. As shown in FIG. 2, sensor array 125-i comprises:
electrical sensor(s) 210-i, which are capable of obtaining
measurements of one or more electrical properties such as voltage,
current, resistance, impedance, inductance, etc.; optical sensor(s)
215-i, which are capable of obtaining measurements of optical
properties such as color, photosensitivity, intensity, etc.;
magnetic sensor(s) 220-i, which are capable of obtaining
measurements of magnetic properties such as magnetic strength, dip
(vertical inclination relative to gravity, consisting of magnitude
in degrees and heading angle from magnetic north), direction (e.g.
pitch/yaw/roll, etc.), polarity, etc.; chemical sensor(s) 225-i,
which are capable of obtaining measurements of chemical properties
such as pH, flammability, salinity, etc.; environmental sensor(s)
230-i, which are capable of obtaining measurements of various
environmental properties, as described in detail below with respect
to FIG. 3; location-based sensor(s) 235-i, which are capable of
obtaining measurements of location-related information such as
geo-location and proximity via, for example, a GPS receiver, an
indoor wireless location system, etc.; orientation sensor(s) 240-i,
which are capable of obtaining measurements such as attitude angle,
pitch angle, gravimetric intensity, etc.; motion-based sensor(s)
245-i, which are capable of obtaining measurements such as speed,
acceleration, etc.; vibration sensor(s) 250-i, which are capable of
obtaining measurements of mechanical vibration such as magnitude,
frequency, etc.; static field sensors 255-i, which are capable of
obtaining measurements of DC; and time-based sensor(s) 260-i that
are capable of establishing highly-precise time references of
events (e.g., environmental events; the time-of-flight of an
injected pulse, which can be used to determine proximity; the
reaching of thresholds, the occurrence of transitions, etc.).
[0049] It should be noted that in some embodiments, one or more of
the above data may be obtained from a remote source instead of an
on-board sensor, or in some instances by both an on-board sensor
and remote source. For example, geo-location information might be
obtained via transceiver 140 from a location server or an off-board
GPS receiver, either instead of, or in combination with
location-based sensor(s) 235-i. It should further be noted that in
some alternative embodiments, sensor array 125-i might comprise a
different set of sensors (e.g., a subset of the sensors depicted in
FIG. 2, a superset of the sensors depicted in FIG. 2, a set of
sensors consisting of a subset of the sensors depicted in FIG. 2 in
combination with one or more additional sensors, etc.).
[0050] FIG. 3 depicts a block diagram of environmental sensors
230-i, as shown in FIG. 2, in accordance with one embodiment of the
present disclosure. Environmental sensors 230-i comprises
thermometer 310-i, which is capable of obtaining temperature
measurements, in well-known fashion; hygrometer 320-i, which is
capable of obtaining humidity measurements, in well-known fashion;
barometer 330-i, which is capable of obtaining barometric pressure
measurements, in well-known fashion; anemometer 340-i, which is
capable of obtaining measurements of wind speed and direction, in
well-known fashion; and radiation sensor 350-i, which is capable of
obtaining radiation level measurements (e.g., infrared,
ultraviolet, visible light, radio frequency, microwave, millimeter
wave, particle, alpha rays, beta rays, gamma rays, etc.).
[0051] As noted above for sensor array 125-i, in some embodiments
some or all of the above environmental data may be obtained from a
remote source instead of, or in addition to, on-board sensor(s). It
should further be noted that in some alternative embodiments,
environmental sensors 230-i might comprise a different set of
sensors (e.g., a subset of the sensors depicted in FIG. 3, a
superset of the sensors depicted in FIG. 3, a set of sensors
consisting of a subset of the sensors depicted in FIG. 3 in
combination with one or more additional sensors, etc.).
[0052] The sensors in sensor arrays 125 can be divided into two
classes: passive sensors, and active sensors. A passive sensor is
noninvasive and obtains measurements silently, through observation
only. Examples include sensors in the set of electrical sensors 210
measuring voltage and current; sensors in the set of orientation
sensors 240 measuring attitude, pitch, and gravimetric intensity;
and so forth. An active sensor, in contrast, injects a stimulus
(e.g., a radio frequency pulse, a DC potential voltage, an
ultrasonic signal, etc.) and measures one or more parameters of the
response to the stimulus. Examples include sensors in the set of
electrical sensors 210 that measure resistance and inductance;
sensors in the set of time-based sensors 260 that measure the
time-of-flight of an injected pulse; and so forth.
[0053] FIG. 4 depicts a first example installation of
power-transfer monitoring device 110 in accordance with one
embodiment of the present disclosure. As shown in FIG. 4, the
installation includes, interconnected as shown: power-transfer
monitoring device 110, electrical source 170, electrical load 190,
of FIG. 1; wall segment 410-1 housing a first portion of a
conductor 480-1, a first portion of a conductor 480-2, a first
portion of a conductor 480-3, and a first junction box 420-1; wall
segment 410-2 housing a second portion of conductor 480-1, a second
portion of conductor 480-2, a second portion of conductor 480-3,
and a second junction box 420-2; wall segment 410-3 housing a third
portion of conductor 480-1, a third portion of conductor 480-2, a
third portion of conductor 480-3, and a third junction box 420-3
comprising an electrical receptacle that can accommodate different
appliance types and sizes and can provide a disconnectable
interface; conductors 180-1, 180-2, and 180-3 connecting
power-transfer monitoring device 110 to electrical source 170; and
conductors 185-1, 185-2, and 185-3 connecting power-transfer
monitoring device 110 to electrical load 190.
[0054] Wall segments 410 serve to isolate the conductors and
protect them from damage, as well as to protect users in the
facility who might otherwise come into contact with them. In some
examples the wall segments may be concrete building foundations or
outdoor earthwork, conduits, or concrete sidewalks.
[0055] FIG. 5 depicts a flow diagram of aspects of a method 500 for
detecting and handling a hazardous state of an electrical
power-transfer system, in accordance with one embodiment of the
present disclosure. The method is described below with respect to
electrical power-transfer system 100 of FIG. 1; however the method
may be performed with respect to some other system. In one
embodiment, the method may be performed during one or more of the
following times: before electrical load 190 is connected, during
transfer of power while electrical load 190 is connected, and after
completion of electrical load 190's power-transfer cycle. It should
be noted that in some implementations, one or more blocks depicted
in FIG. 5 might be performed simultaneously, or in a different
order than that depicted. In addition, while a single execution of
method 500 is depicted in FIG. 5, method 500 may be performed
multiple times (e.g., a pre-determined number of times, at fixed or
variable time intervals; in an infinite loop, etc.).
[0056] At block 501, a stimulus power signal is injected into
electrical power-transfer system 100. The power signal might be a
single impulse, a repeated pulse, an active sensor probe, an
uninterrupted continuous signal such as an AC sine wave, etc. The
particular choice of power signal may be guided with the objective
of eliciting a resonant response. It should be noted that two or
more independent energized injections may overlap (e.g., normal
operating current and an active sensor probe signal, etc.).
[0057] In some embodiments, the sensing cycle of a sensor comprises
the injection of a stimulus signal and subsequent measurement of
the return signal. For example, a proximity sensor may actively
inject a pulse into its associated conductor and measure the
time-of-flight for the reverberant pulse to return.
[0058] In accordance with one embodiment, the power signal is
injected under the control of power-transfer monitoring device 110
by commanding electrical source 170 to connect to a source of
electric-potential, and if loaded, to cause electric current to
flow. This modulates the flow of current, which provides a stimulus
that courses through the power-transfer system 100 and acts as a
probe. The modulation thus enables sensor arrays 125 to measure
changes that are associated with or induced by the power-transfer
activity. As described below, the resultant signal returned to
power-transfer monitoring device 110, which is measured by sensor
arrays 125, can expose and illuminate potential hazards. An example
impulse response characteristic for temperature and voltage is
shown in FIG. 7.
[0059] At block 502, processor 130 of power-transfer monitoring
device 110 receives one or more sensor measurements from one or
more of sensor arrays 125-1, 125-2 and 125-3. In some examples, the
sensor measurements may be made during the injection of the signal,
while in some other examples the sensor measurements may be made
after the injection of the signal. In one embodiment, the sensor
measurements are sampled, with the sampling being triggered by an
interrupt. In some implementations the interrupts might occur at
fixed time intervals, while in some other implementations the
interrupts might occur at variably-sized time intervals. As will be
appreciated by those skilled in the art, in some other embodiments
sampling might be triggered by some other type of event, rather
than an interrupt (e.g., by a detection of a change in a sampled
parameter or in a signal differential, etc.), while in still other
embodiments the sensor measurements might be received continuously
or near-continuously.
[0060] At block 503, the sensor measurements received at block 502
are processed. In one embodiment, blocks 502 and 503 are both
performed by processor 130 in response to a single interrupt or
event. In some other embodiments, blocks 502 and 503 might be
performed in response to separate, successive interrupts/events. In
some implementations the successive interrupts/events might be of
different types, while in some other implementations the successive
interrupts/events might be of the same type.
[0061] In one embodiment, the processing of sensor measurements
includes the computation of functions (e.g., proportional,
integral, and derivative factors; noise removal; imputation;
prognostic projections and estimates; derivatives [e.g., first
derivatives, second derivatives, etc.], averages, moving averages,
etc.). In one implementation, data from sensor arrays 125-1, 125-2
and 125-3 are stored in a three-dimensional data structure, and
successive instances of the data structure are stored in a circular
buffer. In one example, the circular buffer is sufficiently large
to hold data for a complete migration cycle to estimate the
probability of an impending fault condition.
[0062] At block 504, processor 130 detects a hazardous state of
electrical power-transfer system 100 based on the processed sensor
measurements. In one embodiment, state includes one or both of (1)
the state of individual components (e.g. conductors), and (2) the
overall state of electrical power-transfer system 100 (e.g.,
availability, productivity, capacity, safety, etc.).
[0063] Hazardous states may be indicated or suggested by a variety
of conditions, such as variance in one or more conductors (e.g.,
dimensional [cross-sectional] variance along a conductor, material
variance between conductors [which can cause Ohmic variance], etc.)
and/or physical changes in one or more conductors during operation
(e.g., due to magnetic changes, vibration, thermal changes,
elongation contact, etc.).
[0064] In one embodiment, a variety of techniques may be used to
detect hazardous states. One such technique is to compare one or
more aspects of the current state (e.g., conductor impedance,
system capacity, etc.) to a baseline. For example, a baseline
profile may be established for diurnal cycles of observable
characteristics that may affect system performance. These
characteristics may show normal patterns of variance from nominal
that can be predicted for example based on date and time schedule
or meteorological data. For example, the voltage, frequency, and
reluctance of a source of power may be influenced by ambient
thermal conditions on long utility lines and transformers that
supply utility power over long distances. These may also be
affected by incident solar radiation along the line. As another
example, seasonal baseline profile may be established. This may be
useful in desert locations which experience more extreme variance
between summer and winter conditions.
[0065] In some embodiments, baseline references may be adjusted
based on instantaneous sensor readings at the point of use, or on
near-real-time meteorological reports that are associated with
deviations from the baseline. For example, a rainstorm can induce
observable changes in a power transmission line that affect power
quality. Instantaneous observed readings may deviate from an
expected baseline. This variance is range-checked, and used as
predictive measure. Excessive variance may be associated with an
impending fault and may predict an imminent failure condition.
Using these techniques, the device can take action, temporarily
reducing its load and reducing its exposure to fluctuations. This
reduction can serve to isolate any influence from the appliance on
the power source, thus stabilizing the source, and also any
connected distribution equipment that may be connected.
[0066] Another such technique is to identify when one or more
aspects of system behavior exhibit a particular pattern known to be
associated with hazards (e.g., rapid changes in particular
parameters, a change in the relationship between two or more
parameters, departures from typical diurnal patterns, etc.). An
example of a typical diurnal pattern is depicted in FIG. 8, showing
temperature over time. In accordance with one implementation,
time-of-day phase angle measurements provide a more direct measure
of environmental thermal variance, which may include solar exposure
with local inumbration and reflection.
[0067] In some examples, the frequency of the sensing cycle may be
significantly higher than that of the flow modulations of the
operating current (for example, a sensing cycle frequency of
multiple times per second, versus a flow modulation frequency of,
for example, 6 kHz). In such examples, sensing cycles will occur
when operating current flow is off, when current is high, and when
current is modulated at mid-level. Accordingly, two additional
techniques may be used to detect hazardous states: observing the
differential between sensor measurements at various current levels,
and observing the differential between sensor measurements at
different conductor pairs.
[0068] Power quality may be sensed through the waveforms of the
single- and three-phase power being transferred. The dynamic AC
characteristics of the load may be adjusted in order to avoid
excessive current spikes, or to take advantage opportunistically,
to stabilize the source, or to isolate and protect the appliance
from potential problems upstream.
[0069] In some embodiments, both active and passing sensing
techniques may be used in conjunction, such that sensor arrays
125-1, 125-2, and 125-3 are independently capable of active signal
injection for active sensing (e.g., injecting a reference signal at
a specific frequency between a pair of conductors, etc.). In one
example, a 20 kHz signal is injected between sensor arrays 125-1
and 125-2 and the impedance between the two sensor arrays is
measured. During the signal injection, two additional impedance
measurements are made: one between sensor arrays 125-1 and 125-3,
and one between sensor arrays 125-2 and 125-3. The impedance
measurements characterize different aspects of the conductive
environment, and can provide diagnostic clues that indicate
pre-emergent fault conditions.
[0070] A second phase view may be obtained by injecting a 20 kHz
signal between sensor arrays 125-1 and 125-3 and measuring the
impedance between these two sensor arrays. In this second phase
view, additional impedance measurements are made between sensor
arrays 125-1 and 125-2, and between sensor arrays 125-2 and 125-3.
Similarly, a third phase view may be obtained by injecting a 20 kHz
signal between sensor arrays 125-2 and 125-3 and measuring the
impedance between these two sensor arrays. In this third phase
view, additional impedance measurements are made between sensor
arrays 125-1 and 125-2, and between sensor arrays 125-1 and
125-3.
[0071] Impedance between sensor array pairs is just one example of
a property that can be actively measured (i.e., measured after
signal injection). Other examples include Each of the phase views
provides data from a different vantage point, and the overlap in
viewpoint redundancy can potentially provide both consistency
checking and diagnostic capability (e.g., localizing a defect/fault
to a particular conductor, or a particular subset of conductors,
etc.). For example, a galvanic corrosion-induced fault condition
may be visible from only one particular phase view. Suppose, for
example, that corrosive contact exists between sensor arrays 125-2
and 125-3. The interface between these two sensor arrays is
measured actively in the third phase view, and is measured
passively in the first and second phase views. Under normal
conditions (i.e., where there are no defects or faults),
measurements would be symmetrical across all phase views. Under
abnormal conditions, however, local geometry and chemistry, as well
as the geometry of a particular defect/fault may create
asymmetrical signatures that can detect defects and existing
faults, and predict future faults. Further, changes in measurements
over time (e.g., changes in the impedance measurements of the first
phase view at two different times, changes in the differences
between impendence measurements of the first phase view and second
phase view at two different times, etc.) may be used to estimate
rate of corrosion and its hazardous criticality.
[0072] In accordance with one embodiment, measurements are logged,
and the log may be used to guide subsequent off-line diagnostic
analysis. The diagnostic records can be provided for external
analysis by a human technician, or may also be analyzed
algorithmically. For example, the current invention (power-transfer
monitor) may spend most of its service life monitoring a power
system that never experiences a failure or a shut-down event.
Monitoring may be performed continuously over long periods of time.
The frequency of fault events can be zero but the incidence of
suboptimal but subclinical detections or interventions through
modulation may be significantly greater than zero. In these
systems, the record of subclinical event occurrences provides a
prognostic alarm that can detect the early onset of system
degradations long before any failure occurs. Patterns detected in
the log of subclinical events can recommend maintenance procedures
very specifically, and can guide service that designates specific
components for replacement, repair, or refurbishment. This is
valuable in applications that are exposed to high-severity failure
modes, for example in vehicular, aerospace, and weapons
applications. Power monitoring over a long service history provides
a deep view into device life to improve serviceability,
reliability, and operational confidence. In the most
mission-critical or risk-sensitive applications, the tolerance for
modulation interventions can be set to zero or near-zero. This
retains a full capability for modulation to gracefully degrade
performance during an anomaly, but uses a modulation event to
trigger or activate a maintenance procedure or replacement. This
can provide for example a "limp-home" capability that continues to
deliver power at a lower performance level until the service can be
completed. Then after a service procedure has been performed, the
monitor serves to verify operational capability at the start of a
new service life. In some embodiments, passive sensing from
multiple phase views can be employed, either in conjunction with
sensing from multiple phase views, or on its own (i.e., without
multiple-phase-view active sensing). For example, in the case of
grounded single-phase, three conductors may be sensed thermally,
with conductor pairs compared.
[0073] It should be noted that the multiple-phase-view technique
disclosed above can be performed in a similar fashion when there
are four sensors arrays/conductor pairs (e.g., for a three-phase
circuit, etc.), or when there is an even greater number of sensors
arrays/conductor pairs, both with active sensing and/or passive
sensing. It should be noted that in some embodiments, one or more
of blocks 502, 503, and 504 may occur within a monitoring loop not
depicted in the flow diagram.
[0074] At block 505, one or more remedial actions are taken in
response to the hazardous state identified at block 504 are
identified. Action is taken programmatically to avoid the problem;
the information that enabled detection often describes a rich
context that has good diagnostic specificity. This diagnostic
detail may be useful to inform subsequent remedial actions.
Remediation may for example be applied as repairs, maintenance, or
replacement. In this case, the diagnostic information from an event
is stored with the event record in memory 131, recalled and
presented through status device 150 to a user.
[0075] Two classes of automatic or programmatic action that may be
applied are safety shutoff and modulation. Safety shutoff is
invoked when a clear and present hazard is detected, indicating
that operation is unsafe. Modulation may be invoked when conditions
indicate a developing or impending hazardous condition that is
trending away from normal safe operating conditions. This is used
to avoid a problem and reverse the observed operating variance, and
automatically return to normal operating conditions. It should be
noted that not all conditions can be reversed by modulation: for
example, corrosion or wear may be beyond the capability of
modulation. In these cases, modulation provides a "graceful
degradation" to continue operation without necessitating a
shutdown. Continued operation even in a degraded state still has
high value, especially in high-reliability systems where downtime
may be expensive or even catastrophic (e.g., in aircraft and flight
systems, etc.). The farthermost modulation extreme may achieve zero
or near-zero current, with correspondingly zero power transfer.
This case is similar to a safety shutoff, except that conductors
180 & 185 remain energized, and some minimal level of appliance
functionality is maintained.
[0076] In one embodiment, the modulation is implemented in a power
conversion device within load 190, and is performed in response to
a signal from monitoring device 110. The power conversion device
may be an AC/DC converter that converts the variable line voltage
(AC 1-phase or AC 3-phase or DC) to the specific power needs for
the load's internal use. This internal need usually includes a DC
battery.
[0077] In one embodiment, one or more modulation techniques may be
employed, such as pulse width modulation (PWM), frequency
modulation (FM), phase modulation (PM), amplitude modulation (AM),
or some combination thereof. Each of these modulation techniques
constitutes a dimension that is described or prescribed
parametrically, and may be described as "load quality
modulation."
[0078] In one embodiment, three-phase modulation may be employed.
To transfer power in three-phase AC form, an appliance must be
connected to all three of the power phases. The benefits of
three-phase power over single-phase power include improved
stability, constant power over time, equilateral grounding, etc.
The three phases may be three sine waves spaced 120 degrees,
carrying a constant power capacity.
[0079] Power from a three phase line may be converted into a format
that is most favorable for consumption or end-use. When an energy
storage device or battery is used, direct current is a common
format. To convert from the three-phase power transfer mechanism
into the internally-preferred DC, the three conductors may be
connected to three inverters as follows: conductors 185-1 and 185-2
are connected as an input pair to a first inverter; conductors
185-2 and 185-3 are connected as an input pair to a second
inverter; and conductors 185-1 and 185-3 are connected as an input
pair to a third inverter.
[0080] During operation of power-transfer system 100, processor 130
may discover a fault, anomaly, unbalance, or other suboptimal
condition. This detection may be made in the sensor data streams
that originate in sensor arrays 125-1, 125-2, and 125-3 (e.g., via
some characteristic pattern identified in the sensor signals,
etc.). The presence or absence of the pattern in the sensor streams
may enable location to be triangulated down to a single conductor,
either 185-1, 185-2, or 185-2. An example of a geographically local
fault is corrosion that has formed along the conductive metal
pathway, leaking current outside the circuit, or restricting the
normal flow current inside the circuit. The fault may be present on
only one single conductor of the three, with the other two
conductors free of any anomaly or problem.
[0081] As is described in detail below, defects/faults may be
localized via rotating perspective viewpoint relative to an
injected sensor signal. These two directional vectors can be
thought of as a viewing angle and an angle of illumination. Varying
the included angle between these two enhances perceptive power to
detect and localize problems.
[0082] When sensing has detected an anomaly, perspective sensing
and rotating views may be used to narrow down its location
spatially or logically. Once the anomaly's location is known,
mitigating action can be prescribed with pinpoint accuracy. Action
may be implemented by differential modulation in the power
conversion layer of the appliance. Actions may be taken that appear
as a graceful degradation in performance, thereby enabling
continuity of operation and avoiding the need for an abrupt safety
stop.
[0083] In one embodiment, action is taken by differentially
modulating the load profiles on converter/inverter pairs: when an
anomaly is located in a single conductor, only the conversion
devices that are connected to that conductor are modulated. In one
implementation, the modulation is a change in the current profile
(amperes over time), and only conversion devices that are connected
to the affected conductor are modulated. The remaining conversion
device that is not connected to the impacted conductor is not
modulated, and continues operation unimpeded.
[0084] As an example, consider the case where sensor arrays data
indicates the presence of an anomaly. Once the anomaly is detected
processor 130 uses multiple sensor viewpoints to localize the
anomaly to a single affected conductor, in this case 185-3.
Processor 130 forwards the inferred location of to load 190, where
control actions are implemented. The second and third inverters are
subjected to a modulation of their load profiles. This may reduce
the peak current or the power conducted on conductor 185-3. The
first inverter may be commanded to continue its operation
unimpeded, and conductors 185-2 and 185-1 experience no modulation
or degradation.
[0085] The power carried by conductors 185-2 and 185-1 is the sum
of all three phase currents. While two of the phases are modulated,
the available carrying capacity of the remaining phase current is
proportionally increased. This enables recovery of some of the
capacity lost by reducing the capacity of the affected conductor
185-3.
[0086] If and when the sensor arrays detect that an anomaly has
passed, the modulation profile restrictions can be eased. This
allows the system to lift its modulated state and return to
unrestricted functionality. Transitions between these states are
performed automatically under software control.
[0087] Multi-conductor sensing, combined with three-phase power
transfer, provides a synergistic alignment of perceptive power and
prescriptive specificity. This resonant match-up extends the
beneficial capabilities of the invention favorably.
[0088] In one embodiment, the particular modulation technique(s)
are selected dynamically based on the particular hazardous state
that has been detected. In one implementation, sensor data are
associated with the hazardous state to prescribe an appropriate
modulation technique that is communicated to the power conversion
device and performed during power conversion. The system is
pre-programmed with a set of modulation responses to respond to
particular hazardous states (e.g., the most common hazardous
states, etc.). The risk of the sensed hazard may be estimated from
sensed data, and the degree of the modulation response may be
prescribed in proportion to the hazard risk (e.g., a proportional
relationship between the degree of modulation and a "hazardous
state severity scale" from 1 to 10, etc.).
[0089] For example, in a three-phase system, a reduction in
impedance may develop between conductors 185-2 and 185-3, as
detected by sensor arrays (125-1, 125-2, 125-3, and 125-3). The
reduction may be a variance from a design specification, or from a
calibrated value, or from a historical log that is unique to the
device. This condition of reduced-impedance may be caused for
example by accumulation of corroded material or other solid or
liquid contamination between conductors 180-2, 180-3, 185-2 and/or
185-3, or by a variety of other environmental factors. Note that
there are several permutations of conductor pairs where deviance
can be measured and detected.
[0090] The sensed reading deviates from its expected value in the
direction of zero. Readings are made at the sensor arrays 125-1,
125-2, 125-3, and 125-3 and communicated to Processor 130. Software
running in Processor 130 uses the communicated readings to
calculate an instantaneous DeviationRatio, as:
DeviationRatio=1-(ExpectedImpedance-MeasuredImpedance)/ExpectedImpedance)-
. This yields a Ratio as a positive fractional value between 0 and
1 (0% and 100%). This fraction is transformed into a modulation
command and communicated to Electrical Load 190, which interprets
the command for implementation. Because this in this example
corrosive deviance was detected between conductor pair 185-2 and
185-3, the modulation is applied to Inverter 192, which is fed by
the same two conductors 185-2 and 185-3. Inverter 192 implements
the command by modulating its load profile, for example by reducing
the duty cycle of its PWM (pulse-width-modulated) load. This causes
a reduction in the RMS current carried by Inverter 192. The
remaining two inverters 191 and 193 are not affected by this
modulation, and remain functional at their full capacity. The
current carried by Conductor 185-1 is not affected by this
modulation but conductors 185-2 and 185-3 experience a reduction in
their RMS current. This reduces the stress level on
corrosion-impacted conductors 185-2 and 185-3 and on their nearby
electrical environment. This has the effect of avoiding the risk of
a failure event that might be associated with this corrosion. The
modulation event is logged for future review for remediation or
maintenance service. This review might for example recommend
cleaning the area between conductors 185-2 and 185-3, or replacing
contacts, insulation, or conductor material. The cycle is
accomplished with no failure event, and no need to shut down the
system, which remains functional and operational continuously in
spite of the modulation. This process localizes the affected region
accurately and takes action automatically and rapidly with no need
for human attention or intervention, and without shutting down the
system.
[0091] In one embodiment, the system determines whether the
hazardous state has been corrected (e.g., transformed into an
non-hazardous state, etc.) by the modulation response. If the
modulation failed to correct the hazardous state, then a safety
shutdown is performed.
[0092] A safety shutoff event may require an inspection or other
manual supervisory function before permission is given to resume
safe operation. It may also require a minimum time interval to
allow calming or cool-down before restoring operation. Depending on
the nature or severity of the fault condition, an inspection may be
required. This may include a manual visual or electrical inspection
to verify that no damage has occurred. The inspection process may
also be fully automatic, implemented through sensor arrays 125-1,
125-2, 125-3. All sensor arrays are independently operable, and
remain fully functional while Electrical Source 170 is offline, and
when Electrical Load 190 is off-line. This allows for their
autonomous operation for purposes of pre-inspection and safety
qualification.
[0093] After block 505 has been performed, method 500 terminates.
As described above, although a single execution of method 500 is
depicted in FIG. 5, the method may be performed multiple times
(e.g., a pre-determined number of times, at fixed or variable time
intervals; in an infinite loop, etc.).
[0094] In one embodiment, method 500 may be performed during a
"service session," in which (1) electrical load 190 is connected
conductively, (2) power is then transferred or consumed, and (3)
electrical load 190 is then disconnected, ending the session. When
electrical load 190 is a mobile appliance, its mobility is restored
once the session has ended. An example of a power-transfer cycle
during a service session is shown in FIG. 9.
[0095] Concepts employed in the techniques disclosed above (i.e.,
for detecting a hazardous state, performing one or more remedial
actions in response to the detection of the hazardous state, and
diagnosing a cause of the hazardous state) can also be employed for
other types of undesirable states in an electrical power-transfer
system. Such undesirable states may include suboptimal states
(e.g., power delivery that is less than the maximum capability of
the electrical power-transfer system, or is less than a threshold
percentage of the maximum capability [for example less than 80% of
maximum], etc.) distortions in power line quality, variance in
power line quality above a particular threshold, underload,
overload, etc. A method for detecting and handling such undesirable
states is disclosed below and with respect to FIG. 6.
[0096] FIG. 6 depicts a flow diagram of aspects of a method 600 for
detecting and handling an undesirable state of an electrical
power-transfer system (e.g., distortions in power line quality,
variance in power line quality above a particular threshold,
underload, overload, etc.), in accordance with one embodiment of
the present disclosure. Method 600 is described below with respect
to electrical power-transfer system 100 of FIG. 1; however the
method may be performed with respect to some other system. In one
embodiment, method 600 may be performed during one or more of the
following times: before electrical load 190 is connected, during
transfer of power while electrical load 190 is connected, and after
completion of electrical load 190's power-transfer cycle. It should
be noted that in some implementations, one or more blocks depicted
in FIG. 6 might be performed simultaneously, or in a different
order than that depicted. In addition, while a single execution of
method 600 is depicted in FIG. 6, method 600 may be performed
multiple times (e.g., a pre-determined number of times, an infinite
loop, etc.)
[0097] At block 601, a stimulus power signal is injected into
electrical power-transfer system 100. The power signal might be a
single impulse, a repeated pulse, an active sensor probe, an
uninterrupted signal such as an AC sine wave, etc. The particular
choice of power signal may be guided with the objective of
eliciting a resonant response. It should be noted that two or more
independent energized injections may overlap (e.g., normal
operating current and an active sensor probe signal, etc.).
[0098] In some embodiments, the sensing cycle of a sensor comprises
the injection of a stimulus signal and subsequent measurement of
the return signal. For example, a proximity sensor may actively
inject a pulse into its associated conductor and measure the
time-of-flight for the reverberant pulse to return.
[0099] In accordance with one embodiment, the power signal is
injected under the control of power-transfer monitoring device 110
by commanding electrical source 170 to connect to a source of
electric-potential, and if loaded, to cause electric current to
flow. This modulates the flow of current, which provides a stimulus
that courses through the power-transfer system 100 and acts as a
probe. The modulation thus enables sensor arrays 125 to measure
changes that are associated with or induced by the power-transfer
activity. As described below, the resultant signal returned to
power-transfer monitoring device 110, which is measured by sensor
arrays 125, can expose and illuminate potential hazards. An example
impulse response characteristic for temperature and voltage is
shown in FIG. 7.
[0100] At block 602, processor 130 of power-transfer monitoring
device 110 receives one or more sensor measurements from one or
more of sensor arrays 125-1, 125-2 and 125-3. In one embodiment,
the sensor measurements are sampled, with the sampling being
triggered by an interrupt. In some implementations the interrupts
might occur at fixed time intervals, while in some other
implementations the interrupts might occur at variably-sized time
intervals. As will be appreciated by those skilled in the art, in
some other embodiments sampling might be triggered by some other
type of event, rather than an interrupt (e.g., by a detection of a
change in a sampled parameter or in a signal differential, etc.),
while in still other embodiments the sensor measurements might be
received continuously or near-continuously.
[0101] At block 603, the sensor measurements received at block 602
are processed. In one embodiment, blocks 602 and 603 are both
performed by processor 130 in response to a single interrupt or
event. In some other embodiments, blocks 602 and 603 might be
performed in response to separate, successive interrupts/events. In
some implementations the successive interrupts/events might be of
different types, while in some other implementations the successive
interrupts/events might be of the same type. In one embodiment, the
processing of sensor measurements includes the computation of
functions (e.g., proportional, integral, and derivative factors;
noise removal; imputation; prognostic projections and estimates;
derivatives [e.g., first derivatives, second derivatives, etc.],
averages, moving averages, etc.). In one implementation, data from
sensor arrays 125-1, 125-2 and 125-3 are stored in a
three-dimensional data structure, and successive instances of the
data structure are stored in a circular buffer. In one example, the
circular buffer is sufficiently large to hold data for a complete
migration cycle to estimate the probability of an impending fault
condition.
[0102] At block 604, processor 130 detects a undesirable state of
electrical power-transfer system 100 based on the processed sensor
measurements. In one embodiment, state includes one or both of (1)
the state of individual components (e.g. conductors), and (2) the
overall state of electrical power-transfer system 100 (e.g.,
availability, productivity, capacity, safety, etc.).
[0103] Undesirable states may be indicated or suggested by a
variety of conditions, such as variance in one or more conductors
(e.g., dimensional [cross-sectional] variance along a conductor,
material variance between conductors [which can cause Ohmic
variance], etc.) and/or physical changes in one or more conductors
during operation (e.g., due to magnetic changes, vibration, thermal
changes, elongation contact, etc.).
[0104] In one embodiment, a variety of techniques may be used to
detect undesirable states. One such technique is to compare one or
more aspects of the current state (e.g., conductor impedance,
system capacity, etc.) to a baseline. For example, a baseline
profile may be established for diurnal cycles of observable
characteristics that may affect system performance. These
characteristics may show normal patterns of variance from nominal
that can be predicted for example based on date and time schedule
or meteorological data. For example, the voltage, frequency, and
reluctance of a source of power may be influenced by ambient
thermal conditions on long utility lines and transformers that
supply utility power over long distances. These may also be
affected by incident solar radiation along the line. As another
example, seasonal baseline profile may be established. This may be
useful in desert locations which experience more extreme variance
between summer and winter conditions.
[0105] In some embodiments, baseline references may be adjusted
based on instantaneous sensor readings at the point of use, or on
near-real-time meteorological reports that are associated with
deviations from the baseline. For example, a rainstorm can induce
observable changes in a power transmission line that affect power
quality. Instantaneous observed readings may deviate from an
expected baseline. This variance is range-checked, and used as
predictive measure. Excessive variance may be associated with an
impending fault and may predict an imminent failure condition.
Using these techniques, the device can take action, temporarily
reducing its load and reducing its exposure to fluctuations. This
reduction can serve to isolate any influence from the appliance on
the power source, thus stabilizing the source, and also any
connected distribution equipment that may be connected.
[0106] Another such technique is to identify when one or more
aspects of system behavior exhibit a particular pattern known to be
associated with hazards (e.g., rapid changes in particular
parameters, a change in the relationship between two or more
parameters, departures from typical diurnal patterns, etc.). An
example of a typical diurnal pattern is depicted in FIG. 8, showing
temperature over time. In accordance with one implementation,
time-of-day phase angle measurements provide a more direct measure
of environmental thermal variance, which may include solar exposure
with local inumbration and reflection.
[0107] In some examples, the frequency of the sensing cycle may be
significantly higher than that of the flow modulations of the
operating current (for example, a sensing cycle frequency of
multiple times per second, versus a flow modulation frequency of,
for example, 6 kHz). In such examples, sensing cycles will occur
when operating current flow is off, when current is high, and when
current is modulated at mid-level. Accordingly, two additional
techniques may be used to detect undesirable states: observing the
differential between sensor measurements at various current levels,
and observing the differential between sensor measurements at
different conductor pairs.
[0108] Power quality may be sensed through the waveforms of the
single- and three- phase power being transferred. The dynamic AC
characteristics of the load may be adjusted in order to avoid
excessive current spikes, or to take advantage opportunistically,
to stabilize the source, or to isolate and protect the appliance
from potential problems upstream.
[0109] In some embodiments, both active and passing sensing
techniques may be used in conjunction, such that sensor arrays
125-1, 125-2, and 125-3 are independently capable of active signal
injection for active sensing (e.g., injecting a reference signal at
a specific frequency between a pair of conductors, etc.). In one
example, a 20 kHz signal is injected between sensor arrays 125-1
and 125-2 and the impedance between the two sensor arrays is
measured. During the signal injection, two additional impedance
measurements are made: one between sensor arrays 125-1 and 125-3,
and one between sensor arrays 125-2 and 125-3. The impedance
measurements characterize different aspects of the conductive
environment, and can provide diagnostic clues that indicate
pre-emergent fault conditions.
[0110] A second phase view may be obtained by injecting a 20 kHz
signal between sensor arrays 125-1 and 125-3 and measuring the
impedance between these two sensor arrays. In this second phase
view, additional impedance measurements are made between sensor
arrays 125-1 and 125-2, and between sensor arrays 125-2 and 125-3.
Similarly, a third phase view may be obtained by injecting a 20 kHz
signal between sensor arrays 125-2 and 125-3 and measuring the
impedance between these two sensor arrays. In this third phase
view, additional impedance measurements are made between sensor
arrays 125-1 and 125-2, and between sensor arrays 125-1 and
125-3.
[0111] Impedance between sensor array pairs is just one example of
a property that can be actively measured (i.e., measured after
signal injection). Other examples include Each of the phase views
provides data from a different vantage point, and the overlap in
viewpoint redundancy can potentially provide both consistency
checking and diagnostic capability (e.g., localizing a defect/fault
to a particular conductor, or a particular subset of conductors,
etc.). For example, a galvanic corrosion-induced fault condition
may be visible from only one particular phase view. Suppose, for
example, that corrosive contact exists between sensor arrays 125-2
and 125-3. The interface between these two sensor arrays is
measured actively in the third phase view, and is measured
passively in the first and second phase views. Under normal
conditions (i.e., where there are no defects or faults),
measurements would be symmetrical across all phase views. Under
abnormal conditions, however, local geometry and chemistry, as well
as the geometry of a particular defect/fault may create
asymmetrical signatures that can detect defects and existing
faults, and predict future faults. Further, changes in measurements
over time (e.g., changes in the impedance measurements of the first
phase view at two different times, changes in the differences
between impendence measurements of the first phase view and second
phase view at two different times, etc.) may be used to identify
rate of corrosion and its undesirable criticality.
[0112] In accordance with one embodiment, measurements are logged,
and the log may be used to guide subsequent off-line diagnostic
analysis. The diagnostic records can be provided for external
analysis by a human technician, or may also be analyzed
algorithmically. Further, the gain of the preset response may be
tuned or otherwise adjusted to better or more quickly respond to
observed conditions.
[0113] In some embodiments, passive sensing from multiple phase
views can be employed, either in conjunction with sensing from
multiple phase views, or on its own (i.e., without
multiple-phase-view active sensing). For example, in the case of
grounded single-phase, three conductors may be sensed thermally,
with conductor pairs compared.
[0114] It should be noted that the multiple-phase-view technique
disclosed above can be performed in a similar fashion when there
are four sensors arrays/conductor pairs (e.g., for a three-phase
circuit, etc.), or when there is an even greater number of sensors
arrays/conductor pairs, both with active sensing and/or passive
sensing. It should be noted that in some embodiments, one or more
of blocks 602, 603, and 604 may occur within a monitoring loop not
depicted in the flow diagram.
[0115] At block 605, one or more remedial actions are taken in
response to the undesirable state identified at block 604 are
identified. Action is taken programmatically to avoid the problem;
the information that enabled detection often describes a rich
context that has good diagnostic specificity. This diagnostic
detail may be useful to inform subsequent remedial actions.
Remediation may for example be applied as repairs, maintenance, or
replacement. In this case, the diagnostic information from an event
is stored with the event record in memory 131, recalled and
presented through status device 160 to a user.
[0116] Two classes of automatic or programmatic action that may be
applied are safety shutoff and modulation. Safety shutoff is
invoked when a clear and present hazard is detected, indicating
that operation is unsafe. Modulation may be invoked when conditions
indicate a developing or impending undesirable condition that is
trending away from normal safe operating conditions. This is used
to avoid a problem and reverse the observed operating variance, and
automatically return to normal operating conditions. It should be
noted that not all conditions can be reversed by modulation: for
example, corrosion or wear may be beyond the capability of
modulation. In these cases, modulation provides a "graceful
degradation" to continue operation without necessitating a
shutdown. Continued operation even in a degraded state still has
high value, especially in high-reliability systems where downtime
may be expensive or even catastrophic (e.g., in aircraft and flight
systems, etc.). The farthermost modulation extreme may achieve zero
or near-zero current, with correspondingly zero power transfer.
This case is similar to a safety shutoff, except that conductors
180 & 185 remain energized, and some minimal level of appliance
functionality is maintained.
[0117] In one embodiment, the modulation is implemented in a power
conversion device within load 190, and is performed in response to
a signal from monitoring device 110. The power conversion device
may be an AC/DC converter that converts the variable line voltage
(AC 1-phase or AC 3-phase or DC) to the specific power needs for
the load's internal use. This internal need usually includes a DC
battery.
[0118] In one embodiment, one or more modulation techniques may be
employed, such as pulse width modulation (PWM), frequency
modulation (FM), phase modulation (PM), amplitude modulation (AM),
or some combination thereof. Each of these modulation techniques
constitutes a dimension that is described or prescribed
parametrically, and may be described as "load quality
modulation."
[0119] In one embodiment, the particular modulation technique(s)
are selected dynamically based on the particular undesirable state
that has been detected. In one implementation, sensor data are
associated with the undesirable state to prescribe an appropriate
modulation technique that is communicated to the power conversion
device and performed during power conversion. The system is
pre-programmed with a set of modulation responses to respond to
particular undesirable states (e.g., the most common undesirable
states, etc.). The degree of the modulation response may be
determined based on the magnitude of the undesirable state (e.g., a
linear relationship between the degree of modulation and a
"undesirable state severity scale" from 1 to 10, etc.).
[0120] In one embodiment, the system determines whether the
undesirable state has been corrected (e.g., transformed into an
non-undesirable state, etc.) by the modulation response. If the
modulation failed to correct the undesirable state, then a safety
shutdown is performed.
[0121] A safety shutoff event may require an inspection or other
manual supervisory function before permission is given to resume
safe operation. It may also require a minimum time interval to
allow calming or cool-down before restoring operation. Depending on
the nature or severity of the fault condition, an inspection may be
required. This may include a manual visual or electrical inspection
to verify that no damage has occurred. The inspection process may
also be fully automatic, implemented through sensor arrays 125-1,
125-2, 125-3. All sensor arrays are independently operable, and
remain fully functional while Electrical Source 170 is offline, and
when Electrical Load 190 is off-line. This allows for their
autonomous operation for purposes of pre-inspection and safety
qualification.
[0122] After block 605 has been performed, method 600 terminates.
As described above, although a single execution of method 600 is
depicted in FIG. 5, the method may be performed multiple times
(e.g., a pre-determined number of times, at fixed or variable time
intervals; in an infinite loop, etc.).
[0123] In one embodiment, method 600 may be performed during a
"service session," in which (1) electrical load 190 is connected
conductively, (2) power is then transferred or consumed, and (3)
electrical load 190 is then disconnected, ending the session. When
electrical load 190 is a mobile appliance, its mobility is restored
once the session has ended. An example of a power-transfer cycle
during a service session is shown in FIG. 9.
[0124] In accordance with one embodiment, electrical load 190 is
augmented with additional functionality, or "intelligence". In one
example, the intelligent load is capable of detecting a second load
on the same circuit. Large loads, such as EV charging stations, air
conditioners, washers, dryers, electric stoves, etc. are ideally on
their own circuit with an appropriately rated breaker. However,
this is not always possible due to installation costs, limitations
to the panel size, or the home electric service feed. Various
hardware solutions have evolved to enable the sharing of the same
circuit between loads; however, these solutions can be costly. It
would be advantageous if an added load were sufficiently
intelligent to detect that it is being used in a shared circuit
situation, and in response to this detection, automatically
throttle or turn off its own energy use when it detects another
load comes online. We disclose such a load (subsequently referred
to as a "smart load") below.
[0125] In accordance with one embodiment, a smart load continuously
monitors the voltage of the circuit to which it is connected. The
smart load observes and persists the voltage drop that results from
its own operation (original voltage when idle minus new voltage
when fully operational). The smart load further observes and
persists the temperature increase caused by heat dissipation on the
circuit wires supplied by remote sensing.
[0126] In one embodiment, the smart load will enter a transitional
state whenever a voltage drop of similar magnitude is observed
either prior to or during its own operation. The smart load will
not permit active operation when the temperature of the wires is
elevated, and/or when the temperature of the wires matches
previously observed values under load. The smart load will turn off
(e.g., in a single step, in successive steps, etc.) and will
confirm that the circuit voltage has recovered. It will continue to
monitor the heat dissipation on the circuit wires through remote
sensing.
[0127] The smart load will only resume operation if it registers a
voltage increase that matches the previously registered decrease.
It will wait until the circuit wires have sufficiently cooled which
serves as an additional confirmation that no other load is
active.
[0128] The smart load thus enables, for example, the addition of a
smart EV charger to a dryer circuit. This smart charger would have
the capability to detect the presence of another load on the same
circuit and modify its own operation to accommodate this load.
[0129] It is to be understood that the above-described embodiments
are merely illustrative of the present invention and that many
variations of the above-described embodiments can be devised by
those skilled in the art without departing from the scope of the
invention. It is therefore intended that such variations be
included within the scope of the following claims and their
equivalents.
* * * * *