U.S. patent application number 09/824904 was filed with the patent office on 2002-05-16 for rotating variable frequency transformer with high voltage cables.
Invention is credited to McLaren, Donald Gordon, Weeber, Konrad Roman.
Application Number | 20020057027 09/824904 |
Document ID | / |
Family ID | 27396171 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020057027 |
Kind Code |
A1 |
McLaren, Donald Gordon ; et
al. |
May 16, 2002 |
Rotating variable frequency transformer with high voltage
cables
Abstract
A system for transferring power between a first electrical
system and a second electrical system comprises a rotary
transformer (105) comprising a rotor (110) having rotor windings
and a stator (112) having stator windings. The windings of at least
one of the rotor and the stator are high power cables utilized to
obviate employment of a transformer between the one of the rotor
and the stator and one of the first electrical system and the
second electrical system.
Inventors: |
McLaren, Donald Gordon;
(Ontario, CA) ; Weeber, Konrad Roman; (Rexford,
NY) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201
US
|
Family ID: |
27396171 |
Appl. No.: |
09/824904 |
Filed: |
April 4, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60215671 |
Jun 30, 2000 |
|
|
|
60215670 |
Jun 30, 2000 |
|
|
|
Current U.S.
Class: |
310/114 |
Current CPC
Class: |
H02K 47/22 20130101;
H02K 2203/15 20130101; H01F 38/18 20130101; H02J 3/34 20130101;
H01R 39/14 20130101; H01F 38/04 20130101 |
Class at
Publication: |
310/114 |
International
Class: |
H02K 016/00 |
Claims
What is claimed is:
1. A system for transferring power between a first electrical
system and a second electrical system, the system comprising: a
rotary transformer comprising a rotor having rotor windings and a
stator having stator windings; wherein the windings of at least one
of the rotor and the stator are high power cables utilized to
obviate employment of a transformer between the one of the rotor
and the stator and one of the first electrical system and the
second electrical system.
2. The system of claim 1, wherein the windings of both the rotor
and the stator are high power cables.
3. The system of claim 1, wherein the windings of only the rotor
are high power cables.
4. The system of claim 1, wherein the windings of only the stator
are high power cables.
5. The system of claim 1, wherein the high power cables are capable
of operation with greater than 30 kV.
6. The system of claim 1, wherein the high power cables are formed
from one of cross-linked polyethylene and ethylene propylene
rubber.
7. The system of claim 1, wherein the first electrical system and
the second electrical system have differing frequency.
8. The system of claim 1, further wherein the first electrical
system is a first electrical grid and the second electrical system
is a second electrical grid.
9. The system of claim 1, further comprising: a drive control
system; a drive motor which rotates the rotor in response to a
drive signal generated by the drive control system.
10. The apparatus of claim 9, wherein the drive control system
bi-directionally operates the rotor at a variable speed for
transferring power from the first electrical system to the second
electrical system or vise versa.
Description
[0001] This application claims the benefit and priority of U.S.
Provisional patent application Ser. No. 60/215,671, filed Jun. 30,
2000, which is incorporated herein by reference in its entirety.
This application is related to U.S. Provisional Patent Application
Ser. No. 60/215,670, filed Jun. 30, 2000, entitled "HIGH-POWER
ROTARY CURRENT COLLECTOR SYSTEM", U.S. patent application Ser. No.
09/731,875, filed Dec. 8, 2000, entitled "CLEANING/COOLING OF
HIGH-POWER ROTARY CURRENT COLLECTOR SYSTEM"; U.S. patent
application Ser. No. 09/731,879, filed Dec. 8, 2000, entitled
"ENVELOPE FOR SLIP-RING CONTACTING MEMBERS IN HIGH-POWER ROTARY
CURRENT COLLECTOR SYSTEM"; and U.S. patent application Ser. No.
09/731,877, filed Dec. 8, 2000, entitled "SLIP-RING MOUNTING
ASSEMBLY FOR HIGH-POWER ROTARY CURRENT COLLECTION SYSTEM", all of
which are incorporated herein by reference in their entirety
BACKGROUND OF THE INVENTION
[0002] Rotary transformers have been utilized for coupling
multi-phase systems. See, for example, U.S. Pat. No. 3,471,708 to
Rauhut wherein a non-synchronous rotary machine has stator windings
connected to a first three-phase power system grid and rotor
windings connected to a second three-phase system grid. If the
frequency of one system is different from that of the second
system, a torque is exerted on the rotor in one direction or the
other so as to cause rotation of the rotor at a rotational rate
equal to the difference between the network frequencies.
[0003] In one example deployment of a rotary transformer, a rotary
transformer system is connected to transfer electrical power
between a first electrical system (e.g., first electrical grid) and
a second electrical system (e.g., second electrical grid). In such
deployment, one of the rotor assembly and the stator is connected
(e.g., by three phase lines) to the first electrical system, and
the other is connected to the second electrical system. A drive
motor rotates the rotor assembly in response to a drive signal
generated by a control system. The first and second electrical
systems may have a differing electrical characteristic (e.g.,
frequency or phase). The control system can bi-directionally
operate the rotary transformer system at a variable speed for
transferring power from the first electrical system to the second
electrical system or vice versa (i.e., from the second electrical
system to the first electrical system). Further information
concerning such example deployment and variations thereof are
disclosed in the following, all of which are incorporated herein by
reference in their entirety: U.S. Pat. No. 5,953,225; U.S. Pat. No.
5,742,515; U.S. Pat. No. 5,841,267; U.S. Pat. No. 5,952,816; U.S.
patent application Ser. No. 08/825,502; and U.S. patent application
Ser. No. 09/443,220.
[0004] Rotating electrical machines such as the rotary
transformer/converter discussed above are normally manufactured and
designed at operating voltages of 4 kV to 25 kV. Such being the
case, heretofore on each side thereof the rotating
transformer/converter a transformer must be employed in order to
connect to typical transmission level voltages of 15 kV to 400
kV.
BRIEF SUMMARY OF THE INVENTION
[0005] A rotary transformer system obviates the need for
transformers for connecting to a high voltage electrical system
such as an electrical grid or the like by using high voltage cables
as one or both of rotor windings and stator windings. The rotary
transformer system is driven by an electrical machine.
[0006] Thus, in accordance with the present invention, the windings
of at least one of the rotor and the stator are high power cables
utilized to obviate employment of a transformer between the one of
the rotor and the stator and one of the first electrical system and
the second electrical system. In alternate embodments, the high
power cables can be used for windings of one or both of the rotor
and stator. The high power cables are capable of operation with
greater than 30 kV, e.g., and may operate as high as 100 kV or even
higher (e.g., 500 kV). In non-limiting, representative example
embodiments, the high power cables are formed from one of
cross-linked polyethylene and ethylene propylene rubber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a diagrammatic view of a variable frequency rotary
transformer system according to a first embodiment of the
invention.
[0008] FIG. 1A is a diagrammatic view of a variable frequency
rotary transformer system according to a second embodiment of the
invention.
[0009] FIG. 1B is a diagrammatic view of a variable frequency
rotary transformer system according to a third embodiment of the
invention.
[0010] FIG. 2 is a partial schematic, partial perspective view of
portions of the variable frequency rotary transformer system of
FIG. 1.
[0011] FIG. 3 is a diagrammatic view of a variable frequency rotary
transformer system without the high voltage cables of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In the following description, for purposes of explanation
and not limitation, specific details are set forth such as
particular architectures, interfaces, techniques, etc. in order to
provide a thorough understanding of the present invention. However,
it will be apparent to those skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. In other instances, detailed descriptions
of well known devices, circuits, and methods are omitted so as not
to obscure the description of the present invention with
unnecessary detail.
[0013] FIG. 1 shows a variable frequency rotary transformer system
20 according to a first embodiment of the present invention. The
variable frequency rotary transformer system 20 operates in a high
voltage, high current environment having alternating voltages and
current. The variable frequency rotary transformer system 20 is
connected to transfer electrical power between a first electrical
system (e.g., first electrical grid, represented by wires 22) and a
second electrical system (e.g., second electrical grid, represented
by wires 24).
[0014] The variable frequency rotary transformer system 20 includes
a drive control system 104; rotary transformer assembly 105; and a
torque control unit 106 (also known as the rotor drive motor or
drive motor). The drive control system 104 is employed to control
the torque control unit 106. As further shown in FIG. 2, the rotary
transformer assembly 105 includes both a rotor subassembly 110 and
a stator 112. The rotor subassembly 110 includes a rotatable shaft
113, a collector ring assembly 114, and a rotor cage section
116.
[0015] In the example embodiment shown in FIG. 2, the illustrated
variable frequency rotary transformer system 20 is wound with sixty
degree phase belts (a different number of phase belts can be
utilized with the present invention). The present invention
advantageously employs high power cables for the windings of both
the rotor subassembly 110 and stator 112. These high power cables
used for the rotor windings are depicted generally by their phase
belts HV-RA+, HV-RC-; HV-RB+; HV-RA-; HV-RC+; and HV-RB- in FIG. 2,
while the high power cables used for the stator windings are
depicted generally as HV-SA+, HV-SC-; HV-SB+; HV-SA-; HV-SC+; and
HV-SB- in FIG. 2. As explained herein, the use of the high power
cables in lieu of conventional windings enables the variable
frequency rotary transformer system 20 to connect to the first
electrical system and the second electrical system, without the use
of transformers as otherwise would be required.
[0016] The drive motor 104 rotates the rotor subassembly 110 in
response to a drive signal generated by drive control system 104.
The first and second electrical systems may have a differing
electrical characteristic (e.g., frequency or phase). The control
system 104 can bi-directionally operate the rotor subassembly 110
at a variable speed for transferring power from the first
electrical system to the second electrical system or vise versa
(i.e., from the second electrical system to the first electrical
system). Further information describing the structure and the
operation of variable frequency rotary transformer system 20
generally and variations thereof is provided in the following, all
of which are incorporated herein by reference in their entirety:
U.S. Pat. No. 5,953,225; U.S. Pat. No. 5,742,515; U.S. Pat. No.
5,841,267; U.S. Pat. No. 5,952,816; U.S. patent application Ser.
No. 08/825,502; and U.S. patent application Ser. No.
091443,220.
[0017] Since rotating electrical machines are normally manufactured
and designed at operating voltages of 4 kV to 25 kV, then in order
to connect to typical transmission level voltages of 15 kV to 400
kV, such a system would need to have a transformer on each side. In
this regard, FIG. 3 shows the employment of variable frequency
rotary transformer system without the invention of assembling the
windings from high voltage cables. In particular, FIG. 3 shows that
without the inventive use of high voltage cables, the collector
ring assembly 114 is connected through an ISO-phase bus 330 and
transformer 332 to the first electrical system, while the stator is
connected by an ISO-phase bus 340 and transformer 342 to the first
electrical system. The transformer 332 and transformer 342 are
necessary in the FIG. 3 scheme to get the transmission voltage down
to levels more commonly associated with rotating machinery.
[0018] It should be understood that the present invention
encompasses the rotor windings, the stator windings, or both being
made with high voltage cables. For example, FIG. 1A shows a
variation of the variable frequency rotary transformer system 20A
wherein high voltage cables are employed only for the stator
windings. FIG. 1B, on the other hand, shows yet another variation
of the variable frequency rotary transformer system 20B wherein
high voltage cables are employed only for the rotor windings.
[0019] Thus, the present invention connects two power systems
together which may not necessarily be the same frequency, or they
may have the same nominal frequency and differ instantaneously by
small amounts, or they may in fact be a 50 Hz verses 60 Hz
interconnection application where there is a consistence
difference. A rotating electrical machine provides the transformer
action between the two systems, and a torque machine provides the
torque part of the power transfer.
[0020] In the variable frequency rotary transformer system 20 of
the present invention, one or more of either of its rotor or stator
windings is formed with high voltage cables and is connected
directly to the transmission system. The high voltage cables do not
necessarily have the same voltages, depending on the design
configuration desired.
[0021] As used herein, a "high voltage" cable is capable of
operation with greater than 30 kV, and may operate as high as 100
kV or even higher (e.g., 500 kV). Example high voltage operation
scenarios include 69 kV and 138 kV. A high voltage cable preferably
has an extruded insulation system. Example compositions for high
voltage cables include cross-linked polyethylene (XLPE) and
ethylene propylene rubber EPR.
[0022] The present invention has many advantages, including
elimination of one or more transformers. The variable frequency
rotary transformer system 20 is essentially a single transforming
device which connects grids of two different operating
characteristics (e.g., frequencies). The variable frequency rotary
transformer system 20 as shown in FIG. 1 has high voltage on the
stator, across the air gap between rotor and stator, and on the
rotor subassembly 110.
[0023] The present invention thus can reduce the cost of layout of
the variable frequency rotary transformer system, and enhances
performance. The variable frequency rotary transformer system 20
requires less footprint, fewer parts, higher reliability, and
enhanced efficiency. Characteristics of the variable frequency
rotary transformer system 20 can be tailored to particular
sites.
[0024] As a variation, the variable frequency rotary transformer
system can have its rotor conductors and normal design voltages of
6 kV-20 kV, with its rotating set of leads connected to an axial
transformer. This variation eliminates slip rings from the machine,
and has the transformer with the rotating and stationary part which
then leads out at transmission level.
[0025] High voltage insulation can also be involved in variable
frequency rotary transformer system 20. For high voltage
insulation, a cooling fluid such as air, hydrogen, oil, or SF.sub.6
may be applied as a cooling and partial insulation medium. In this
and other regards, see U.S. Provisional Patent Application Ser. No.
60/215,670, filed Jun. 30, 2000, entitled "HIGH-POWER ROTARY
CURRENT COLLECTOR SYSTEM"; U.S. patent application Ser. No.
09/731,875, filed Dec. 8, 2000, entitled "CLEANING/COOLING OF
HIGH-POWER ROTARY CURRENT COLLECTOR SYSTEM"; U.S. patent
application Ser. No. 09/731,879, filed Dec. 8, 2000, entitled
"ENVELOPE FOR SLIP-RING CONTACTING MEMBERS IN HIGH-POWER ROTARY
CURRENT COLLECTOR SYSTEM"; and U.S. patent application Ser. No.
09/731,877, filed Dec. 8, 2000, entitled "SLIP-RING MOUNTING
ASSEMBLY FOR HIGH-POWER ROTARY CURRENT COLLECTION SYSTEM", all of
which are incorporated herein by reference in their entirety.
[0026] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *