U.S. patent application number 13/747215 was filed with the patent office on 2013-05-30 for power line communication system and an intelligent meter.
This patent application is currently assigned to PULSE UTILITIES INTERNATIONAL LIMITED. The applicant listed for this patent is Stephen Allen Abbot, John Richard Futter, Rand Cary Huso, James Lee Allworthy Martin, Gerard Brendan Rowe. Invention is credited to Stephen Allen Abbot, John Richard Futter, Rand Cary Huso, James Lee Allworthy Martin, Gerard Brendan Rowe.
Application Number | 20130136132 13/747215 |
Document ID | / |
Family ID | 41168521 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130136132 |
Kind Code |
A1 |
Abbot; Stephen Allen ; et
al. |
May 30, 2013 |
POWER LINE COMMUNICATION SYSTEM AND AN INTELLIGENT METER
Abstract
A power line communication system including a plurality of
intelligent devices in communication with a power line and operable
to monitor energy usage at a site and communicate usage data onto
the power line, and a controller also in communication with the
power line, wherein each intelligent device maintains a routing
table identifying a first set of other intelligent devices
downstream of it relative to the controller that it can communicate
with directly and identifying a second set of other intelligent
devices downstream of it relative to the controller that it can
communicate with through one or more of the first set of other
intelligent devices.
Inventors: |
Abbot; Stephen Allen;
(Waikanae, NZ) ; Futter; John Richard;
(Wellington, NZ) ; Martin; James Lee Allworthy;
(Auckland, NZ) ; Rowe; Gerard Brendan; (Auckland,
NZ) ; Huso; Rand Cary; (Duvall, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Abbot; Stephen Allen
Futter; John Richard
Martin; James Lee Allworthy
Rowe; Gerard Brendan
Huso; Rand Cary |
Waikanae
Wellington
Auckland
Auckland
Duvall |
WA |
NZ
NZ
NZ
NZ
US |
|
|
Assignee: |
PULSE UTILITIES INTERNATIONAL
LIMITED
Kingsland
NZ
|
Family ID: |
41168521 |
Appl. No.: |
13/747215 |
Filed: |
January 22, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13432878 |
Mar 28, 2012 |
|
|
|
13747215 |
|
|
|
|
12417464 |
Apr 2, 2009 |
8170524 |
|
|
13432878 |
|
|
|
|
10583527 |
|
|
|
|
12417464 |
|
|
|
|
Current U.S.
Class: |
370/392 |
Current CPC
Class: |
H04B 2203/5433 20130101;
H04B 3/546 20130101; G01R 22/063 20130101 |
Class at
Publication: |
370/392 |
International
Class: |
H04B 3/54 20060101
H04B003/54 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2003 |
NZ |
530254 |
Claims
1. An intelligent device (9) for a power line communication system
(100) that has stored in memory (903) information uniquely
specifying the identity of the intelligent device (9) and includes
an interface (906) for data communication with a power line and is
operable to perform a configuration process including the steps of
using said interface (906) to: a) detect data of a first data type
(WCHM packets) through the interface and in response thereto
extract from the data of a first data type (WCHM packets) and
record in memory identity information for the source of the data of
a first data type (WCHM packets) and generate on said interface
(906) data of a second data type (IHY packets) that have as a
destination address the source of the data of a first data type
(WCHM packets) and includes the information specifying the identity
of the intelligent device (9); b) detect data of a second data type
(IHY packets) that have the intelligent device (9) as a destination
address and in response thereto extract from the data of a second
data type (IHY packets) and record in memory the identity of the
source of the data of a second data type (IHY packets) and generate
on said interface (906) data of a third data type (IHT packets)
that includes information identifying the source of the data of a
second data type (IHY packets) and the information specifying the
identity of the intelligent device (9); c) detect data of a third
data type (IHT packets) and in response extract there from and
record in memory information identifying the source of the data of
a third data type (IHT packets) associated with the information
identifying the source of the data of a second data type (IHY
packets) included in the data of a third data type (IHT packets)
and generate data on said interface (906) containing the
information identifying the source of the data of a third data type
(IHT packets), the information identifying the source of the data
of a second data type (IHY packets) included in the data of a third
data type (IHT packets) and the information specifying the
intelligent device's identity.
2. The intelligent device of claim 1, wherein the data generated in
step c) is addressed to at least one source of data detected in
step a).
3. The intelligent device of claim 2, wherein the steps of
extracting and recording in step c) are only performed for data of
a third data type that are addressed to the intelligent device.
4. The intelligent device of any one of claims 1 to 3, wherein the
address of the intelligent device is the same as the information
specifying the intelligent device's identity.
5. The intelligent device of any one of claims 1 to 4 further
operable to determine an indicator of the quality of communication
between itself and the source of detected data and rank identity
information recorded in memory dependent on said indicator.
6. The intelligent device of any one of claims 1 to 5, operable to
in response to detection of data of a second data type generate
data of a fourth data type including as a destination address the
source of the data of a second data type and the configuration
process may further include the steps of using said interface to
detect data of a fourth data type that have the device as a
destination address and in response thereto generate on said
interface data of a first data type.
7. The intelligent device of any one of claims 1 to 6, operable to
ignore detected data of a second data type that were generated by a
source that was recorded in memory as a source of data of a first
data type in in step a).
8. The intelligent device of any one of claims 1 to 7, operable to
use said interface to generate data of a first data type and
wherein the data of a first data type include a counter, wherein
step a) further includes identifying the value of the counter of
any data of a first data type detected, associate the value of the
counter with the recorded identity information for the source of
the data of a first data type, increment the value of the counter
and allocate the incremented value to a counter in any data of the
first data type generated by the intelligent device as a result of
data received from the source of the data of a first data type.
9. The intelligent device of claim 8, operable to ignore detected
data of a first data type that has a counter value more than a
threshold value.
10. The intelligent device of claim 9, wherein the threshold value
is a value related to the value of the counter from the last data
of a first data type received.
11. The intelligent device of claim 10, wherein the threshold value
is one more than the value of the counter from the last data of a
first data type received.
12. The intelligent device of any one of claims 1 to 11, wherein
the data of a third data type include a counter and the data
generated in step c) is in the form of data of a third data type
and the intelligent device associates the value of the counter with
the information recorded in step c) that identifies the source of
the data of a third data type and the intelligent device increments
the counter when generating data of a third data type in response
to detection of data of a third data type in step c).
13. The intelligent device of any one of claims 1 to 12, operable
to also generate data onto said interface otherwise than in
accordance with the configuration process.
14. The intelligent device of any one of claims 1 to 12, operable
to generate text messages onto said interface.
15. The intelligent device of any one of claims 1 to 12, operable
to receive control messages through said interface and communicate
control messages to a power distribution board to facilitate load
shed dependent on said control messages.
16. A power line communication system (100) including a plurality
of power lines (7a-c) in communication with a controller (3)
through a power line modem (6), each power line having a plurality
of intelligent devices as claimed in claim 1 in communication with
it, wherein the controller (3) is operable as one of said plurality
of intelligent devices (9) and is also in communication with a
computer controller (2) that is operable to receive data from the
intelligent devices (9) via the controller (3) and to send data to
the intelligent devices (9) via the controller (3).
17. The power line communication system of claim 16, wherein data
other than configuration data, which is generated onto a power line
by an intelligent device or the controller, includes a destination
address and an intermediate address, wherein each intelligent
device monitors communications on the power line and if the
destination address of communications matches information
identifying the source of the data of a second data type (IHY
packets) included in the data of a third data type (IHT packets)
that was recorded by an intelligent device in accordance with step
c), then that intelligent device regenerates the data, but with the
intermediate address field comprising the information identifying
the source of the data of a third data type (IHT packets) recorded
in step c) that is associated with the information identifying the
source of the data of a second data type (IHY packets) included in
the data of a third data type (IHT packets) that matches the
destination address.
18. A power line communication system (100) including a plurality
of intelligent devices (9) in communication with a power line and
operable to monitor energy usage at a site and communicate usage
data onto the power line, and a controller (3) also in
communication with the power line, wherein each intelligent device
(9) maintains a routing table identifying a first set of other
intelligent devices (9) downstream of it relative to the controller
(3) that it can communicate with directly and identifying a second
set of other intelligent devices (9) downstream of it relative to
the controller (3) that it can communicate with through one or more
of the first set of other intelligent devices (9).
19. The power line communication system of claim 18, wherein the
routing table further identifies a third set of other intelligent
devices upstream of it relative to the controller that it can
communicate with directly.
20. The power line communication system of 18 or claim 19, wherein
the routing tables are formed by an interrogation process initiated
by the controller that requests the intelligent devices that can
receive data directly from the controller over the power line to
respond with information identifying what other intelligent devices
the intelligent devices that can receive data directly from the
controller over the power line can communicate with either directly
or through further intelligent devices, wherein the intelligent
devices that can be communicated with through said further
intelligent devices are identified through an interrogation process
conducted by said further intelligent devices.
Description
TECHNICAL FIELD
[0001] This invention relates to communication methodologies and
systems utilising power lines, such methodologies and systems often
also referred to as mains communication methods and systems. In
particular, but not exclusively, the present invention relates to
the establishment of a power line communication network and a
method of communicating over the network.
BACKGROUND
[0002] Communication over power lines has been proposed and used
for remote metering. In typical systems for remote metering, a
central controller communicates with a meter using a superimposed
signal on the mains network. A meter sends an acknowledgement
signal back to the central controller and may perform some function
dependent on the message received.
[0003] Two well known problems that need to be overcome by power
line communication systems are the noisy environment and
potentially large signal attenuation. Various reading techniques
and communication protocols have been developed to address these
problems, for example using meters as digital relays to enable
communication from the central controller to each of the meters.
Examples of power line communication systems using signal repeaters
are described in European patent publication No. 0 201 253 B1 and
international patent publication no. WO 95/01030.
[0004] Advances in meter technology have provided improved
functionality. For example, meters may communicate by a wireless
link with other meters and with network controllers to perform
various functions. An example of such a system is described in
international patent publication no. WO 97/29466. A problem with
such meters is the additional costing complexity resulting from the
wireless communication. Also, as radio spectrum becomes
increasingly in demand, the use of wireless communication from
potentially millions of sources may not be commercially viable in
many cases.
[0005] A mains network provides an extensive existing
infra-structure. Further exploitation of the existing mains
infra-structure would be advantageous. For example, increased
functionality, both in terms of control and monitoring of the power
network may be achieved, including improved metering and providing
additional services to customers.
[0006] As a consequence of deregulation in the power supply
industry in many countries, achieving reconciliation of power
supplied and determining the power used and network losses has
become a significant problem. The problem arises principally on the
low voltage distribution network, where more than one retailer
exists as well as a separate to lines company. There is a need for
improved measurement of network losses so that accuracy in power
reconciliation can be improved.
[0007] It is thus an object of the present invention to provide a
power line communication system and method that provides additional
functionality for one or both of power network management and the
provision of network services, or at least to provide the public
with a useful alternative.
Definitions
[0008] Computer controller--computerised apparatus for managing
communications within a mains communication network. The computer
controller typically includes one or more suitable computer
processors, a suitable operating system and suitable
application(s). For example and without limitation the computer
controller may be a computer or network of computers operating
Windows NT.RTM. or Linux.
[0009] Intelligent device--a device that includes a computer
processor and associated memory and a communication interface
allowing the device to perform at least some communication
functions. Intelligent devices include, without limitation, a relay
or meter including a computer processor, memory and communication
interface.
[0010] Power usage profiling--identification of patterns of use of
power at a specific site or by a specific device that is connected
to the mains communication network.
[0011] Utility--a retail supplier of power to customers.
SUMMARY OF THE INVENTION
[0012] According to a first aspect of the present invention, there
is provided an intelligent device for a power line communication
system that has stored in memory information uniquely specifying
the intelligent device's identity, includes an interface for data
communication with a power line and is operable to perform a
configuration process including the steps of using said interface
to: [0013] a) detect data of a first data type through the
interface and in response thereto extract from the data of a first
data type and record in memory identity information for the source
of the data of a first data type and generate on said interface
data of a second data type that have as a destination address the
source of the data of a first data type and includes the
information specifying the intelligent device's identity; [0014] b)
detect data of a second data type that have the intelligent device
as a destination address and in response thereto extract from the
data of a second data type and record in memory the identity of the
source of the data of a second data type and generate on said
interface data of a third data type that includes information
identifying the source of the data of a second data type and the
information specifying the intelligent device's identity; [0015] c)
detect data of a third data type and in response extract there from
and record in memory information identifying the source of the data
of a third data type associated with the information identifying
the source of the data of a second data type included in the data
of a third data type and generate data on said interface containing
the information identifying the source of the data of a third data
type, the information identifying the source of the data of a
second data type included in the data of a third data type and the
information specifying the intelligent device's identity.
[0016] Preferably, the data generated in step c) is addressed to at
least one source of data detected in step a).
[0017] Preferably, the steps of extracting and recording in step c)
are only performed for data of a third data type that are addressed
to the intelligent device.
[0018] Preferably, the address of the intelligent device is the
same as the information specifying the intelligent device's
identity.
[0019] Preferably, the intelligent device is further operable to
determine an indicator of the quality of communication between
itself and the source of detected data and rank identity
information recorded in memory dependent on said indicator.
[0020] Preferably, the intelligent device is operable to in
response to detection of data of a second data type generate data
of a fourth data type including as a destination address the source
of the data of a second data type and the configuration process may
further include the steps of using said interface to detect data of
a fourth data type that have the device as a destination address
and in response thereto generate on said interface data of a first
data type.
[0021] Preferably, the intelligent device is operable to ignore
detected data of a second data type that were generated by a source
that was recorded in memory as a source of data of a first data
type in in step a).
[0022] Preferably, the intelligent device is operable to use said
interface to generate data of a first data type and wherein the
data of a first data type include a counter, wherein step a)
further includes identifying the value of the counter of any data
of a first data type detected, associate the value of the counter
with the recorded identity information for the source of the data
of a first data type, increment the value of the counter and
allocate the incremented value to a counter in any data of the
first data type generated by the intelligent device as a result of
data received from the source of the data of a first data type.
[0023] Preferably, the intelligent device is operable to ignore
detected data of a first data type that has a counter value more
than a threshold value. Preferably, the threshold value is a value
related to the value of the counter from the last item(s) of data
of the first data type received. More preferably, the threshold
value is one more than the value of the counter from the last data
of a first data type received.
[0024] Preferably, the data of a third data type include a counter
and the data generated in step c) is in the form of data of a third
data type and the intelligent device associates the value of the
counter with the information recorded in step c) that identifies
the source of the data of a third data type and the intelligent
device increments the counter when generating data of a third data
type in response to detection of data of a third data type in step
c).
[0025] Preferably, the intelligent device is operable to also
generate data onto said interface otherwise than in accordance with
the configuration process.
[0026] Preferably, the intelligent device is operable to generate
text messages onto said interface.
[0027] Preferably, the intelligent device is operable to receive
control messages through said interface and communicate control
messages to a power distribution board to facilitate load shed
dependent on said control messages.
[0028] According to a second aspect of the present invention, there
is provided a power line communication system including a plurality
of power lines in communication with a controller through a power
line modem, each power line having a plurality of intelligent
devices as described in the preceding paragraphs in communication
with it, wherein the controller is operable as one of said
plurality of intelligent devices and is also in communication with
a computer controller that is operable to receive data from the
intelligent devices via the controller and to send data to the
intelligent devices via the controller.
[0029] Preferably, data other than configuration data, which is
generated onto a power line by an intelligent device or the
controller, includes a destination address and an intermediate
address, wherein each intelligent device monitors communications on
the power line and if the destination address of communications
matches information identifying the source of the data of a second
data type included in the data of a third data type that was
recorded by an intelligent device in accordance with step c), then
that intelligent device regenerates the data, but with the
intermediate address field comprising the information identifying
the source of the data of a third data type recorded in step c)
that is associated with the information identifying the source of
the data of a second data type included in the data of a third data
type that matches the destination address.
[0030] According to a third aspect of the present invention, there
is provided a power line communication system including a plurality
of intelligent devices in communication with a power line operable
to monitor energy usage at a site and communicate usage data onto
the power line and a controller also in communication with the
power line, wherein each intelligent device maintains a routing
table identifying a first set of other intelligent devices
downstream of it relative to the controller that it can communicate
with directly and identifying a second set of other intelligent
devices downstream of it relative to the controller that it can
communicate with through one or more of the first set of other
intelligent devices.
[0031] Preferably, the routing table further identifies a third set
of other intelligent devices upstream of it relative to the
controller that it can communicate with directly.
[0032] Preferably, the routing tables are formed by an
interrogation process initiated by the controller that requests the
intelligent devices that can receive data directly from the
controller over the power line to respond with information
identifying what other intelligent lo devices the intelligent
devices that can receive data directly from the controller over the
power line can communicate with either directly or through further
intelligent devices, wherein the intelligent devices that can be
communicated with through said further intelligent devices are
identified through an interrogation process conducted by said
further intelligent devices.
[0033] Further aspects of the present invention may become apparent
from the following description, given by way of example of
preferred embodiments only and with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1: shows a diagrammatic representation of a power line
communication system in accordance with an aspect of the present
invention.
[0035] FIG. 2: shows a block diagram of a meter in accordance with
the present invention.
[0036] FIG. 3: shows a block diagram of a controller in accordance
with the present invention.
[0037] FIG. 4: shows a representation of the information and
functions performed by the database in the communication system of
FIG. 1.
[0038] FIGS. 5a, b: show diagrammatically an example of
configuration packet communications in the communication system of
FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 shows a schematic representation of a mains
communication and control network 100 in accordance with the
present invention. The mains communication and control network 100
includes a mains communication network 1. This forms the lower
levels of a hierarchal communications network topology that
supplies power to customer sites 8a-i that are connected to the
mains communication network 1 and also forms a low voltage
sub-network of a larger mains network 101, which typically includes
a high voltage network that supplies high voltage three phase power
to the mains communication network 1.
[0040] A computer controller 2 provides the upper levels of the
communications network topology. The computer controller 2
includes, in this example of a preferred embodiment, a central
control unit 2A, which communicates with the mains communications
network 1 through a communications controller 2B. A database 2C is
provided for the central control unit 2A, containing the necessary
control information for the mains communication network 1 and also
containing power use information from the mains communication
network 1. Customer billing may be managed by a billing system
2D.
[0041] The mains communication network 1 shown in FIG. 1 may be one
low voltage sub-network of many in the wider mains network 101. The
communications controller 2B may communicate with a large number of
such sub-networks.
[0042] The mains communication network 1 includes a controller 3,
which is suitably located at a transformer 4. The transformer 4 may
receive high voltage power from the mains network 101 and output
low voltage power to the rest of the mains communication network 1.
The computer controller 2, particularly the communications
controller 2B may communicate with the controller 3, through for
example a wireless communication channel 5. Other communication
channels may be used.
[0043] The controller 3 includes three power line modems 6, one
modem per phase 7a-c of the mains communication network 1 on the
low voltage or demand side of the transformer 4. The power line
modems 6 may, for example use a power-line carrier employing FSK
modulation with a carrier frequency in the range of 67 kHz to 87
kHz. Each phase 7a-c feeds into a number of the customer sites
8a-i. Each of the customer sites 8a-i includes a meter 9, with each
meter 9 being an intelligent meter. Some further customer sites
connected to the phases 7a-c may not have intelligent meters, but
these are unimportant to the operation of the present invention and
therefore are not shown in the accompanying drawings or described
herein.
[0044] The mains communication network 1 may include one or more
micro-generation or energy storage facilities 14. In FIG. 1, two
micro-generation/energy storage facilities 14 are shown. The
micro-generation/energy storage facilities 14 may represent for
example, small hydro-generators, solar-generators, wind-generators
or fuel cells and may be located at any one or more of the customer
sites 8a-i or be separate from the customer sites 8a-i. The
micro-generation/energy storage facilities 14 each include a meter
9A.
[0045] The communication functions of the mains communication and
control network 100 are now described with reference to the example
function of meter data collection. The controller 3, through the
appropriate power line modem 6, polls a meter 9 for the power
consumed at a site 8a-i since the last time the associated meter 9
at the site was polled. The meter 9, which includes its own
transmitter, then sends information indicating the power consumed
to the controller 3, where it is buffered until requested by the
computer controller 2. The central control unit 2A then initiates a
communication session with the controller 3 through the
communications controller 2B, which receives the buffered
information through the communication channel 5. The central
control unit 2A then updates the database 2C with the newly
received information. The billing system 2D may then generate a
bill at a required time, based on the information stored in the
database 2C. In addition, the updated billing information may be
sent by the central control unit 2A to the meter 9 for display on
the customer display unit 10.
[0046] Each meter 9 used in the mains communication network 1 is an
intelligent power meter. Typically, the meter 9 will replace any
existing electro-mechanical meter at each customer site 8a-i. A
block diagram representation of a meter 9 is shown in FIG. 2. The
meter 9 includes a computer processor 900, which may for example be
a Dallas 5002FP, 8051 compatible processor. External memory 901,
which may be SRAM, is provided in communication with the processor
900 and the operations of the processor 900 are timed by a clock
902. The meter 9 also includes EEPROM 903. The meter 9 may
communicate with optional external devices, through a serial
communications interface 904. The meter 9 may also include its own
display 905 for communication of information to users. A power line
modem 906 allows the meter 9 to communicate with the controller 3
through a phase of the mains communication network 1.
[0047] The meter 9 records the power usage using an energy
measurement module 907. For example, the energy measurement module
may be a SAMES SA9102C energy-metering integrated circuit,
available from South African Micro-Electronic Systems, Pretoria,
South Africa. The resulting data is stored in memory 901 using an
encryption algorithm. Bidirectional energy measurement modules are
also available from South African Micro-Electronic Systems for use
in a bidirectional meter.
[0048] The EEPROM 903 contains the starting meter count, the number
of pulses for each kilowatt hour, the number and type of
connections to the meter, type of devices attached to the serial
communications interface 904, and the functions of any additional
outputs. Identification information for the meter 9 that identifies
the meter from other meters, referred to herein as an electronic
serial number, is also stored in a protected part of the EEPROM
903.
[0049] The computer processor 900 has precedence over
communications while the meter reading is accumulated in hardware.
A hardware register (not shown) provided for the meter reading is
read by the computer processor 900, then reset when the
communications channel is not in use.
[0050] When the central control unit 2A sends a poll to a meter the
poll includes a specification of the current time. Upon receipt of
a time packet from the central control unit 2A, the communications
controller 2B sets its clock if it differs from that in the time
packet. The time packet will be queued together with all the other
packets for sending to the controller 3 when the connection is
established. During the time the packet is queued for transmission,
the current system time will continue advancing. Therefore, when
the connection is established, and the time is forwarded to the
controller 3, the time fields of the packet will be updated to the
current system time.
[0051] Data is requested from each meter 9 by the controller 3
periodically, for example once every several hours. Contained in
the request for data packet (initiated by the controller) is the
correct time. The meter 9 will therefore be refreshed with the
correct time periodically. The variable transmission delay to the
meters 9 should also be accounted for. Since each message is
acknowledged, the round trip time divided by two can be calculated,
and may be referred to as the latency. The controller 3 sends each
individual meter 9 a time signal corrected by the latency
applicable to that meter 9. The latency used for a current
transmission may be based on historical information or a further
communication from the controller 3 may cause the meter 9 to
advance its time.
[0052] One of the optional external devices that may be connected
to the meter 9 through the serial interface 904 is a customer
display unit 10. The customer display unit 10 may have increased
display capabilities and display information to the customer, such
as the amount due since last payment, recent consumption
information and the total meter reading. In addition, messages sent
from the central control unit 2A or from elsewhere to the meter 9
may be displayed on the customer display unit 10.
[0053] FIG. 3 shows a block diagram of a controller 3. The
controller 3 includes a processor 300 for controlling the three
power line modems 6a-c through serial communication buses and
manages the receipt, transmission and storage of information from
the various meters 9 and from the communications controller 2B. A
memory 301 is provided to store a routing table (see herein below)
and a communications interface 302, suitably a wireless
communications interface, is provided to allow communication with
the communications controller 2B.
[0054] The communications controller 2B is a real time processing
system that links the central control unit 2A and database 2C with
each controller 3 and subsequently each meter 9. The communications
controller 2B may communicate with the central control unit 2A via
a serial communications link or Ethernet using TCP/IP. Where the
meters 9 in the mains communication network 1 can generate alarms,
the communications controller 2B preferably receives the alarm
signals and forwards these on to the central controller 2A. The
communications controller 2B includes an interface to communicate
with the controller 3, which in FIG. 1 is a wireless interface,
although a leased line modem, standard dial up modem, or
fibre-optic modem may be used instead. As stated herein above, the
communications controller 2B preferably communicates with a
plurality of controllers 3.
[0055] The central control unit 2A stores an operating system such
as Windows NT.RTM.. It also includes appropriate software to manage
the database 2C. The central control unit 2A performs essentially
two main functions, the first being to manage the database 2C and
the second to control the functions of the mains communication
network 1.
[0056] FIG. 4 shows a representation of the functions of the
database 2C. Power usage data from each meter 9, which has been
received through the controller 3 and communications controller 2B,
is stored in memory. The database 2C may include an analysis
function to analyse the raw power usage data and provide specific
output results. A query functionality may be provided to allow the
billing system 2D to retrieve either or both of the raw power usage
data or results of the analysis function. In addition, the database
2C may store the routing tables that dictate the path that data
communications take through the mains communication network 1. The
formation and use of the routing tables are described in more
detail herein below. The central control unit uses the routing
tables when sending out information to the meters 9. Database 2C
may also include the location and technical specification of each
controller 3 and each meter 9. The controllers 3 and meters 9 may
be identified in the database 2C by their electronic serial number,
which is used by the central control unit 2A to distinguish between
the various controllers 3 and meters 9 and also to allow each
controller 3 and each meter 9 to identify the information
communicated within the mains communication network 1 that is
destined for it. The location information may be used for the
purposes of billing, repair of faults and for intelligent
relaying.
[0057] The computer controller 2 may perform statistical analysis
of the usage data, which may be periodically updated, to provide
power usage profiling. The power usage profiling may assist a power
utility in the estimation of demand, for instance, by profiling
supply from particular distribution transformers 4 to their
respective mains communication network 1. The power usage profile
for the customers of a utility supplied from a particular grid exit
point provides a current inventory of energy usage. The utility may
therefore determine in an almost real-time manner what its bill for
supply from that grid point should be.
[0058] Power usage profiling may also benefit a utility in terms of
asset management. Specifically, the power usage profile obtained
from the controller 3 provides information on the load profile for
its associated transformer 4 and phases 7a-c. Changes in usage
pattern can be used to detect certain events, such as loss of
supply to an area caused by a distribution fault, accidental
disconnection of individual premises and/or to indicate
tampering/fraud. It also provides the utility with accurate,
monitored, quality of supply (i.e. outages) information. Such
information is of use for scheduling asset maintenance, upgrades
and replacement. Preventative maintenance may be assisted by
monitoring the quality of network assets. This may be achieved by
measuring changes in power line communication quality through the
network. Information about communication quality is retrieved
periodically. Specifically, bit error rate tests may be performed
routinely during auto-configuration of the network and packet error
rate tests can also be performed on request. By identifying trends
of increasing error rates over time, ageing network assets can be
identified.
[0059] The above described functionality, together with many other
functions that may be provided, for example by other external
devices connected to the meter 9, require bi-directional
communication between the mains communication network 1 and
computer controller 2 and within the mains communication network 1.
An important aspect of the present invention is the method of
communication between these two networks and within the mains
communication network 1. To establish the communication channels, a
number of routing tables are formed and stored in the computer
controller 2 and mains communication network 1. The routing tables
identify the various paths that communications may take between the
computer controller 2 and mains communication network 1, in
particular between the central control unit 2A and each meter
9.
Formation of Routing Tables
[0060] The central control unit 2A and the controllers 3 are the
primary controllers in respect of the formation of routing tables.
The central controller 2A uses a priori knowledge of the network
topology to separate the various meters 9 into several sets, each
set defined by all the meters 9 and their attached optional devices
connected to a single phase of a particular transformer 4. The
controller 3 is responsible for forming the routing table for the
phases in which it is in communication with. This subdivision may
reduce the time to create the routing tables and facilitate the
recreation of sections of the logical network defined by the
routing tables to overcome local communication problems. Recreation
of the logical network may be achieved by a controller sending out
WCHM packets (see herein below) and waiting for responses in the
same way that the logical network is first created.
[0061] Referring now to FIG. 5, a diagrammatic representation of
the packet flows for establishing the routing tables is shown. Upon
initialisation, or upon prompting by the central control unit 2A,
the controller 3 generates and transmits to each of its serial
communication buses a packet of a first type, referred to herein as
the WHO_CAN_HEAR_ME (WCHM) packet. The power line modems 6, which
are intelligent modems, each receive the WCHM packet and in
response thereto send back to the controller 3 a packet of a second
type referred to herein as an I_HEAR_YOU (IHY) packet. The IHY
packet indicates to the controller 3 that a modem is present on
that serial communication bus and includes a field containing the
electronic serial number of the modem. The controller 3 records how
many power line modems 6 it is in communication with, their
electronic serial number, and on which serial bus they are located.
The controller 3 may then collate the IHY packets and send a packet
to the central control unit 2A of a third type referred to herein
as an I_HEARD_THESE (IHT) packet that specifies the electronic
serial number of each modem.
[0062] The controller a may then send a packet of a fourth type,
referred to herein as the WHO_CAN_YOU_HEAR (WCYH) packet. The WCYH
packet prompts each power line modern 6 to generate a WCHM packet
on its output, which represents one of the phases 7a-c of the mains
communication network 1. The WCHM packet includes the electronic
serial number of the power line modem 6 that sent the packet. The
power line modem 6 may optionally have the same electronic serial
number as the controller 3 to which it is connected. Optionally,
the power line modems 6 (and meters 9) may automatically generate,
after a predetermined delay, a WCHM packet after receipt of a WCYH
packet.
[0063] Each meter 9 at each customer site 8a-8i monitors the phase
to which they are connected and upon receipt of a WCHM packet by a
meter 9, the meter 9 enters the electronic serial number in the
WCHM packet into its routing table as a primary parent i.e. a
device from which it can receive communications directly. The meter
9 responds to the WCHM packet with an IHY packet addressed to the
source of the WCHM, which in this case is a power line modem 6. The
IHY packet includes a field containing the electronic serial number
of the meter 9 that received the WCHM packet. The power line modems
6 receive the IHY packets from the various meters 9, collate these
and send notification to the controller 3 identifying each meter 9
that responded to their respective WCHM packet in an I_HEARD_THESE
(IHT) packet, which includes the electronic serial numbers
contained in all the IHY packets received. The controller 3 then
enters in its routing table the electronic serial numbers from the
IHT packet as a primary child i.e. devices to which it can send
information directly using it associated power line modems 6.
[0064] Referring now to FIG. 5b, the controller 3 then sends out a
WCYH packet to each primary child meter through the appropriate
power line modem 6. Each primary child meter 9 acknowledges receipt
of the WCYH packet and also generates a WCHM packet on its output,
which is a phase from the transformer 4. In an alternative
embodiment, each meter 9 may automatically generate a WCHM packet
after receiving such a packet. Each meter 9 that receives this WCHM
packet returns an IHY packet. Each primary child meter 9 records in
its routing table as primary children the electronic serial number
of all meters that returned an IHY packet to it and each meter 9
that received a WCHM packet adds the primary child meter as a
direct parent in their individual routing table. Each primary child
meter 9 also sends through its power line modem 906 an IHT packet
to the controller 3 through the power line modem 6 indicating the
electronic serial number contained in IHY packets that it received.
The controller 3 then adds the electronic serial number as
secondary children in its routing table (i.e. meters that can be
communicated with via another meter logger). The controller 3 also
associates each secondary child with each of the primary children
that sent an IHT packet containing the electronic serial number of
that secondary child. This enables the controller 3 to identify to
which primary child information should be sent in order to reach a
particular secondary child.
[0065] Each meter 9 identifies two or more paths back to the
controller 3. To achieve this, each meter 9 records the electronic
serial number of any meter from which it received a WCHM packet.
The source of the first WCHM packet received could be identified as
Parent 1. The source of the second WCHM packet received could be
identified as Parent 2. Similarly, the sources of any subsequent
WCHM packets could be recorded as Guardians. The Parent and
Guardian meters thus identified represent alternative paths back to
the controller 3.
[0066] The above configuration process continues, with the
controller 3 sending WCYH packets to each secondary child through
the appropriate primary child in order for it to identify its
tertiary children. The controller 3 then sends WCYH packets to the
tertiary children through the primary and secondary child meter
loggers and so on until all meters 9 have been entered into the
routing table of the controller 3. Each meter 9 maintains its own
routing table, extracting the electronic serial numbers from IHT
packets received from its direct children and associating the
serial numbers with its direct children. Thus, each meter knows all
the other meters with which it can communicate directly (its
parents and primary children) and also knows all the meters it can
communicate with indirectly through each of its primary
children.
[0067] The IHT packets may be addressed to the parents of a meter
or simply transmitted onto the power line. If the IHT packets are
addressed, recipient parent meters may simply record the identity
information of the secondary children associated with the identity
information of the sender of the IHT. The recipient meters then
forward the IHT packets to their parents, who will forward the
packet to their parents, associating the identity information
contained in the packet with their relevant primary child and so on
until the controller 3 receives the packet. If the IHT packets are
not addressed, then each recipient meter compares the source of the
IHT packet to all of its children and adds the identity information
in the IHT packet only if there is a match. The recipient meter
associates the identity information in the IHT packet with the
child that matched the source of the IHT packet and then addresses
the IHT packet to its parents.
[0068] To avoid continuous loops in the configuration process, each
meter 9 ignores IHY packets that it receives containing the
electronic serial number of any meter that is listed as a parent.
Also, should the identity information in any IHT packet match a
parent of the recipient meter or itself, the IHT packet is
ignored.
[0069] In one embodiment, when the controller 3 transmits a WCHM
packet, it immediately follows this with a bit error rate test.
Each meter 9 will receive the WCHM packet and bit error rate test
and respond with an IHY packet and a quality indicator based on the
bit error rate test. Each meter 9 also sends a bit error rate test
when it sends a WCHM. Thus, the controller 3 and each meter 9 can
record for each meter that it is in communication with, the quality
of the communication path to that meter. This process allows each
meter to rank the various communication paths to both its parents
and its children, using the highest quality communication path
first. If the communication path of highest quality should fail,
for example by failure to receive an acknowledgement of receipt
packet, the controller 3 or meter 9 uses the next highest quality
communication path, if one exists.
[0070] The network configuration packets WCHM, IHY, WCYH and IHT
are used to create a logical power-line network structure. At least
selected of these configuration packets contain the electronic
serial number of the controller 3 and this electronic serial number
is relayed by each meter 9. For example, each WCHM packet contains
the electronic serial number of the controller 3. Where a meter
sends the WCHM packet, it determines the electronic serial number
from the WCYH packet that it received. Every meter 9 stores the
electronic serial number of its controller 3 in EEPROM 903. This
logical network, the structure of which is determined by the parent
and child links in the routing tables, will be updated periodically
to ensure that the logical network remains current.
[0071] The system may also recreate the logical network on the
occurrence of one or more particular events. Any device within the
mains communication network 1 may transmit onto its associated
phase a packet referred to herein as a NETWORK_CHANGED (NC) packet.
Typically, it will be the meters 9 at any of the customer sites
8a-i that will transmit a NC packet. During the lifetime of a
logical network between periodic updates, the network may change,
for example due to routine maintenance (e.g. a street may be
switched to another phase of a transformer) or by adding or
removing meters 9. If this happens the new meter, or one that was
previously connected to a different controller, will detect the
traffic on the network and notice a different controller electronic
serial number in the packets communicated over the phase to which
it is connected. When this happens, that meter will send a NC
packet onto the phase and meters 9 that detect the NC packet, relay
the packet to the controller 3, which initiates a recreation of
that part of the network.
[0072] The variable noise and attenuation on the mains network has
significant consequences for meter communications. Specifically,
meters that could be contacted at the time the logical network was
last configured (either at a pre-programmed time or as a result of
a NETWORK_CHANGED packet) may not necessarily be contactable at
some later instant. Maintaining communications between the central
control unit 2A and each meter 9 may be particularly important for
real time control of the mains communication network 1, for example
to provide for load shed.
[0073] The central control unit 2A maintains a list of all
contactable meters 9. To achieve this, the controller 3 sends out
PING packets to individual meters 9 in its routing table, at times
when there is no other network traffic, and monitors the responses
to build a list of the currently contactable meters 9. Meters 9
that were in the logical network when it was created but can't now
be contacted are therefore identified. Should they remain out of
contact using the current routing table for a certain predetermined
period, a local network recreation is initiated by the controller
3. In addition, if a meter 9 is unable to contact another meter 9
(determined by failure to receive an acknowledgement or other
return information) after a predetermined number of tries, for
example three attempts using all available paths, an error is
generated by the transmitting meter and sent to the controller 3.
Should the meter remain out of contact for too long a period, a
local network recreation is initiated by the controller.
[0074] A manual over-ride may be provided to allow for the
recreation of the logical network on demand and to specify fixed
communication channels within the logical network. For example, the
central control unit 2A may send packets referred to herein as
YOU_HEARD_THESE (YHT) and YOUR_PARENT_IS (YPI). These packets
respectively identify the meter's children and its parent or
parents and guardians.
[0075] The quality of communications between meters can be
determined by use of a packet error rate test. The central control
unit 2A can request a controller to initiate a packet error rate
test between any desired meters. A known signal is transmitted,
including a signature identifying it as a packet error rate test.
The recipient meter 9 records the error rate and forwards this to
the controller 3. The controller 3 in turn forwards the result to
the central control unit 2A. Should the packet error rate test
results be unacceptably low, the options available to the central
control unit 2A include initiating a local network recreation or
manually reconfiguring the meters routing tables using the YHT and
the YPI packets. Communication quality indicators other than a
packet error rate test may be used if required.
[0076] When the logical network is recreated, the previous logical
network is saved as a backup network. This allows reconstruction of
a previous working logical network should the new network be
inoperable for some reason.
[0077] In the foregoing example of formation of routing tables,
only a two level table in the child direction is formed in each
meter--its direct children and all the meters that the direct
children can communicate with. The meter does not know whether any
child is a secondary, tertiary or higher level child. Similarly,
the controller 3 and central control unit 2A do not know where each
meter is in the hierarchy apart from the primary children of the
controller 3. Also, only the direct parents are recorded. This
embodiment is preferable as reducing the memory requirements for
the routing tables and reducing network communications for
establishing the logical network.
[0078] In an alternative embodiment, a counter may be added to the
IHT packets, which is incremented each time the IHT packet is
relayed to a parent. Therefore, each meter knows how far away each
meter is in terms of transfers through other meters. The IHT meters
may also include a quality indicator that provides an accumulated
indication of the quality of communication between meters, taking
into account the retransmissions that take effect. This information
can be associated with each child and used by the meters and the
controller that receives the IHT packet to choose a path to a
particular meter. Each meter may then, either know how many steps
away each meter is or alternatively know the meters that are one,
two, three, four and five steps away, with those that are more than
five steps away being grouped together.
[0079] Also, a counter may also be associated with each WCHM
packet, which is incremented each time a meter sends out a new WCHM
packet. A meter may ignore a WCHM packet if the counter in it is
too much higher than the counter in the last WCHM packet they
received. For example, to achieve an efficient routing table, if
the counter in a WCHM packet is two or more values higher than the
counter in the last WCHM packet, it may be ignored.
[0080] The WCYH packets may further accumulate in order the
electronic serial numbers of all the meters through which it
`travelled` so that each meter can record fully the path back to
the controller 3, or at least more than one step back to the
controller 3.
Data Communication
[0081] During operation, each meter 9 listens to all communications
on the phase 7a-c to which it is connected. Each packet transmitted
onto the network by a device contains the electronic serial number
of the source of the packet, the electronic serial number of the
device that is the final destination for the packet, and an
intermediate meter electronic serial number if a relay is required.
The packet is received by a meter 9 designated as the intermediate
one (if one is designated), and that meter will change the
intermediate meter electronic serial number to the next meter in
the path to the device having the destination electronic serial
number (using information stored in its routing table) and
transmits the modified packet.
[0082] The meter identifies the appropriate route over which to
transfer a packet by a software routine that examines its routing
table upon receipt of a message destined for another meter or for
the controller. The destination of any message is dictated by an
electronic serial number field. If the message destination is the
controller 3, then the meter 9 forwards the message to its parent.
The parent repeats the process and forwards the message to its
parent and so on until the message is delivered to the controller.
If the message destination is another meter, the meter that
received the message examines its routing table to see if the
destination meter is a child. If so, the routing table is further
examined using a software routine that identifies the appropriate
intermediate destination of the packet. This routine works
backwards from the destination electronic serial number to identify
its parent, and then the parent of that parent and so on until it
is one level below the meter that has received the message. This
may only ever be a two stage process if the meter does not know how
far away other meters in its routing table are. The packet is then
despatched to this intermediate destination meter and the process
repeated.
[0083] Each packet is sent by a particular device in the network to
an intermediate meter up to three times before flagging an error
and giving up on that communications path. If the communications
fail on an upstream path (i.e. the message is being relayed to the
controller) then the meter will try to relay the message through
its second parent. Should this route also fail, then the message
will be relayed through one of the guardian meters. If this also
fails and the communications don't get through to a meter one level
upstream (i.e. closer to the controller) the meter is designed to
attempt to jump over the meter just upstream and attempt to
communicate with one further upstream. This is done by examining
the routing table and identifying the parent's parent (if this
information is available) and relaying the message through this
meter. Should communications fail on the downstream path (i.e. the
message is being relayed from the controller) the meter is designed
to attempt to jump over the meter just downstream and attempt to
communicate with one (two levels) further downstream. This is done
by examining the routing table and identifying the intermediate
electronic serial number that would have been used by the meter
that wasn't responding, and relaying the signal directly to this
intermediate electronic serial number.
[0084] If all else fails (on either upstream or downstream paths),
a meter 9 may request help, using a packet referred to herein as a
HELP_TRANSPORT packet, from any meter that can provide an alternate
path to the destination meter or controller. Responses to this
HELP_TRANSPORT packet are examined and a choice is made as to which
of these to use as the next intermediate meter. The packet will be
forwarded to this meter, by updating the intermediate meter
electronic serial number to match that in the selected response and
that meter will take over the responsibility of getting the packet
to the next intermediate or final destination meter. The sending
meter may optionally update its routing table to include as a child
the new intermediate meter in the path to the destination meter to
which it was originally trying to send.
[0085] The data section of the packets should be encrypted, but the
data section control word should not be encrypted. The data section
control word must be immediately recognisable to allow alarm
traffic to take precedence over other types of information, and to
allow the time data to be updated as it is being transferred from
meter to meter.
[0086] Some mains communication networks may not have a controller
3, perhaps due to being of such a small size that a controller can
not be justified. In FIG. 1, a diagrammatic representation of such
a network is referenced 1A. The mains communication network 1 may
be used to relay data to the mains communication network 1A. One or
more specific meters 9, for example the meter 9 at customer site 8i
acts as a relay to the mains communication network 1A, in
particular to one or more meters 9B that can communicate with the
meter at site 8i. The link between networks may be provided via a
radio or dial-up telephone connection, in which case the meters
designated as the link between networks are provided with the
appropriate radio or telephone modem 11. The routing tables of the
link meters and of the meters in the subsidiary network are
manually configured using the network configuration packets
described herein above YOU_HEARD_THESE (YHT) and YOUR_PARENT_IS
(YPI).
[0087] To increase communication reliability, the packets are
broken up into small pieces and reassembled by the destination
meter or by the controller modem. The size of the packets is an
important design variable for any mains communication network and
size selection typically represents a trade-off between reliability
and efficiency of communication.
[0088] To determine the maximum permissible packet size, an
experimental method may be used. Over a period of time sufficiently
long to represent a normal range of conditions over the network,
which may be as long as several months and at various times of the
day and under a variety of weather conditions, the mains
communication network is sounded using meters equipped with bit
error rate software. One meter continuously transmits while the
other meters operate in receive mode. A known pattern is sent and
time-stamped errors are stored by the receivers. These error files
are then analysed to determine that the noise on the channel is
bursty in nature and this may be used to determine the optimum
packet size.
[0089] Differing length packets are used to convey information,
with very short packets reserved for high priority messaging and
longer packets up to the maximum length used for low priority
messaging. For example alarm messages and load shed control signals
(see herein below) may take the highest and second highest priority
and have the lowest packet length.
Upgrading of Software
[0090] A potential disadvantage of intelligent meters is the
difficulty of upgrading software to enhance functionality.
Typically in prior art systems this can only be achieved by
physically visiting each site, temporarily taking the meter out of
service and downloading new software into the meter. The meters 9
of the present invention are provided with a computer processor 900
capable of In-Application-Programming (IAP) to enable remote
software updates. The STMicroelectronics uPSD3234A microcontroller,
available from STMicroelectronics of Geneva, Switzerland, supports
IAP and includes dual banks of flash memory and a control register
to allow its 8032 controller to run from one flash bank while
erasing and updating the other bank. More than one version of the
meter software can be stored in each meter 9, so that it is
possible to drop back to an earlier version of the software if
problems arise. The capability of remote software updates also
permits the change of modem carrier frequencies and baud rate to
enhance message transfer.
Network Loss Measurement
[0091] As a consequence of deregulation in the power supply
industry, reconciliation of power supplied, power used and network
losses has become a significant problem. The problem arises
principally on the low voltage sub-network, where more than one
retailer exists as well as a separate lines company. An additional
meter, a low voltage master meter 12 may be provided to solve this
problem. Specifically, the low voltage master meter 12 is a device
placed between the distribution transformer 4 and the controller 3
that measures the total power supplied from the transformer 4 over
all three phases. This power supply figure may be metered, for
example, on a half-hourly basis and accumulated results forwarded
to the controller 3 on a periodic basis. When all use data from the
meters 9 and the power supply figure from the low voltage master
meter 12 has been returned to the central control unit 2A, the
database 2C can be used to determine line loss as the difference
between power supplied and power used.
[0092] In addition, the efficiency of the transformer 4 may be
measured. The low voltage master meter 12 and a high voltage meter
13 with pulse output remotely monitor distribution transformer
efficiency. Specifically, the high voltage meter 13 is placed on
the primary of the distribution transformer 4. It reads input
3-phase power on a half-hourly basis. The low voltage master meter
12 records total power output from the transformer on a half-hourly
basis. At fixed intervals the controller 3 requests the half-hourly
readings from both the high voltage meter 13 and the low voltage
master meter 12 and stores these readings for subsequent forwarding
to the central control unit 2A and database 2C. The database 2C is
then able to use these readings to determine transformer
efficiency.
Private-Side Applications of Mains Communication Network
[0093] The mains communication network described herein provides
increased flexibility in the control of the power network and in
the provision of additional services to customers. Examples of new
applications for customers are provided below.
[0094] The mains communication network 1 may monitor the status of
various devices and machines. This is achieved by connecting a
serial interface 904 of a meter 9 to the device or machine. For
domestic premises, an intelligent PLC relay can be used to automate
a device or monitor an essential device such as a dialysis machine
in the home. For hospital or rest-home applications, an intelligent
PLC relay can be used to remotely monitor (for example from a
nurse's station) the status of an essential piece of mains-powered
equipment at a patient's bedside.
[0095] For residential "community" developments, the meters 9 may
be used to automate the front gate and other limited or restricted
access points such as a pool complex and for control of external
lighting without the need for individual wiring to each dwelling.
In one embodiment, a body-corporate residential development may
have "always-on" web access in which all key control points (e.g.
front gate and pool gates) have a web-cam in communication with a
phase 7a-c, which links back to the residential development's
central office, which is also on a phase 7a-c. Residents could then
access the central office through the web to view the web-cam
picture and grant or decline access. The caretaker or manager of
the complex would have the ability to over-ride access or
time-of-day controlled features by accessing the central office via
the web. An advantage of this system is that individual wiring to
each premises is not required.
[0096] The meters 9A in FIG. 1 may be dual meters. The meters 9A
facilitate the monitoring and control of energy storage devices and
of embedded generators so that their energy is made available to
the grid at appropriate times. This control, when used in
combination with power usage profiling, allows improved management
of the energy supply within the entire mains communication network
100. A benefit of this may be a reduction in the need for spinning
reserve. Specifically, the current power usage profile can be used
(in combination with "historical" records) to determine when
embedded generators should be turned on. Such generators could be
switched on either by their owners or remotely by the utility by
instructing the central control unit 2A to send an appropriate
packet.
[0097] Furthermore, improved network management may be achieved
using load shedding. The meters 9, together with an appropriate
distribution board 15 (see FIG. 1) connected to the serial
interface 904, permit remote load shedding. Specifically, a
customer may offer up appliances for remote load shedding. The
utility monitors customer power usage over a short period, say 2
months. On the basis of the power usage profile so determined, the
utility offers the customer 6 special billing rate in return for
permitting the utility to remotely shed load at the customer's
premises. In addition, the customer can view their usage profile,
via the web, and use this information to alter their usage pattern
if appropriate. Load shedding is achieved by the central control
unit 2A sending a LOAD SHED PACKET to a meter 9, the LOAD SHED
PACKET designating the device that should be disconnected by a
distribution board 15. The meter 9 then instructs the distribution
board 15 to make the appropriate switching.
[0098] In one embodiment of the invention, power usage profiling
may be used to indicate illness, for example by a significant
increase or decrease in power usage or lack of change in power
usage over an extended period. Specific customer sites 8a-8i may
request a follow up call or visit should their power usage change
(or not change) significantly to check that they are not
immobilised or seriously unwell. Specifically, consumers with
serious medical problems, who wish to remain living alone, can
identify themselves to the utility and request monitoring of their
power usage profile on a near real-time basis. Should their power
usage profile depart significantly from the norm, notification of a
potential problem is raised by the central control unit 2A to an
administrator.
[0099] Using the infrastructure of the present invention, customers
may be provided the option to have a dual-tariff agreement. At
present, two meters are required to log power usage for customers
on a dual tariff agreement. One meter is used for one particular
tariff period and switched off at the time when the second tariff
applies. Usage during the second tariff period is recorded on the
second meter. Within the tariff periods no information is normally
available on time-of-use, with the meter simply recording total
usage. By using a meter 9 with the infrastructure of the present
invention, including the database 2C, there is no need for a second
meter. Reconciliation with the dual tariff structure can be
achieved using records stored in the database 2C.
[0100] In some cases, customers may prepay their power account.
Previously, if the account became in deficit or became in deficit
for a certain period and/or by a certain amount, the supply of
power would be discontinued. When the database 2C detects an
account in deficit beyond some defined "grace period", the load
shedding functionality is used to disconnect the bulk of the supply
to the premises. The system could provide such customers only with
an emergency supply, for example supply sufficient for lighting and
a small amount of heating.
[0101] Text messages may be distributed via power line carrier.
Specifically, via their meter 9 or customer display unit 10, a
customer can arrange to receive text messages from and send text
messages to, for example the meters 9 of other individuals, a
structure (e.g. a body corporate), or to a wide area network 16 via
the central control unit 2A. Advertising for a local community may
be provided using the text message functionality. Specifically,
individual consumers with a meter 9 can authorise their utility to
add their electronic serial number to an address list for local
advertisers or community groups. Local businesses and community
groups can then arrange to have advertising messages or community
notices forwarded to these consumers via the central control unit
2A.
[0102] For applications where an alarm is generated, in addition to
the usual alarm notification procedures, a text message may be sent
to the neighbouring properties should an alarm be triggered. Should
an intruder be on the premises, it is likely a neighbour could
notify the Police in advance of the arrival of a security guard.
Also, nominated contacts (such as nearest neighbours) may be sent a
text message when a medical alarm is tripped or when the "at risk"
power usage profile threshold is crossed. Such notification would
be additional to any telephone contact specified in the event of an
alarm. The telephone contact may be initiated directly by the meter
9 through a telephone modem connected to its serial interface 904
or alternatively by the central control unit 2A in respect to the
alarm notification.
[0103] Where in the foregoing description reference has been made
to specific components or integers having known equivalents, then
those equivalents are hereby incorporated herein as if individually
set forth.
[0104] Although the foregoing description of the invention has been
given by way of example with reference to the accompanying
drawings, those skilled in the relevant arts will appreciated that
modifications or improvements may be made thereto without departing
from the scope of the invention as defined in the appended
claims.
* * * * *