Electric utility system with superconducting magnetic energy storage

• US 6,906,434 B1
• Filed: 11/24/1999
• Issued: 06/14/2005
• Est. Priority Date: 01/29/1999
• Status: Expired due to Term

• Current Assignee: American Superconductor Corporation
• Original Assignee: American Superconductor Corporation
• Inventors: Brown, Donald L., Folts, Douglas C., Kehrli, Arnold P., Buckles, Warren Elliott, Diaz De Leon, John A. II, Koeppe, Paul Frederick
• Primary Examiner(s): Sircus, Brian
• Assistant Examiner(s): Rios, Roberto J
• Application Number:
  US09/449,435
• Time in Patent Office: 2,029 Days
• Field of Search: 307/64, 307/103, 307/102, 307/105, 323/208, 323/233, 323/205, 323/207, 361/62, 361/76, 361/88, 361/80, 363/40, 363/98
• US Class Current: 307/64
• CPC Class Codes: H02J 3/185 wherein such reactive element is purely inductive, e.g. superconductive magnetic energy storage systems [SMES]
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]
• CPC Class Codes: Y02E 40/20 Active power filtering [APF]
• CPC Class Codes: Y02E 40/60 Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Abstract

a voltage recovery device is configured to provide real and reactive power to a utility power network at a sufficient level and for a sufficient duration to recover the voltage on the utility power network within a predetermined proportion of the nominal voltage, following a fault condition detected on the utility power network. Moreover, the voltage recovery device reduces the overall transmission losses in a utility power system.

Claims

1. A voltage recovery device for connection to a utility power network including a transmission line which carries a nominal voltage and a distribution line network connected to the transmission line network, the distribution line network carrying a distribution voltage less than the nominal voltage on the transmission line network, the voltage recovery device comprising an energy storage unit connected in shunt to the distribution line network and configured to transfer real and reactive power between the utility power network and voltage recovery device at a level and for a duration to recover the voltage on the utility power network to within a predetermined proportion of the nominal voltage, following a fault condition detected on the utility power network.

2. The voltage recovery device of claim 1 wherein the voltage recovery device is configured to transfer a combination of real and reactive power.

3. The voltage recovery device of claim 2 wherein the voltage recovery device is configured to provide real and reactive power to the utility power network to within 0.90 P.U. of the nominal voltage within 0.5 seconds.

4. The voltage recovery device of claim 2 further comprising:

an inverter electrically coupled to the distribution line network; and

a controller connected to the inverter and configured to control the amount of real and reactive power transferred between the energy storage unit and the distribution line network.

5. The voltage recovery device of claim 4 wherein the energy storage unit includes a superconducting magnet.

6. The voltage recovery device of claim 4 wherein the energy storage unit is selected from a group consisting of a flywheel, a battery, a capacitive energy storage system bank, a compressed gas energy source, and a fuel cell system.

7. The voltage recovery device of claim 4 further comprising a magnet interface connected between the energy storage unit and the inverter.

8. The voltage recovery device of claim 1, wherein the real power is transferred from the voltage recovery device at a substantially constant voltage for a predetermined period of time.

9. The voltage recovery device of claim 8, wherein, after the predetermined period of time, the real power is transferred from the voltage recovery device at a substantially constant rate.

10. A method of stabilizing a utility power network including a transmission line which carries a nominal voltage and a distribution line network connected to the transmission line network, the distribution line network carrying a distribution voltage less than the nominal voltage on the transmission line network, the method comprising:

electrically connecting in shunt a voltage recovery device having an energy storage unit to the distribution line network,

detecting a fault condition on the utility power network; and

operating, in response to detecting the fault condition, the voltage recovery device to transfer real power and reactive power to the distribution line network at a level and for a duration to recover the voltage on the utility power network to within a predetermined proportion of the nominal voltage.

11. The method of claim 10 further comprising electrically coupling an inverter to the distribution line network, wherein operating the voltage recovery device including controlling the inverter to control the level of real power and level of reactive power transferred between the energy storage unit and the distribution line network.

12. The method of claim 10 further comprising configuring the voltage recovery device to provide real and reactive power to the transmission network to promote quick recovery of voltage to within acceptable utility standards within 0.5 seconds.

13. The method of claim 10 further comprising configuring the voltage recovery device to provide real and reactive power to the transmission network to within 0.90 P.U. of the nominal voltage within 0.5 seconds.

14. The method of claim 10 wherein the energy storage unit includes a superconducting magnet.

15. The method of claim 10 wherein the energy storage unit is selected from a group consisting of a flywheel, a battery, a capacitive energy storage system bank, a compressed gas energy source, and a fuel cell system.

16. The method of claim 10, wherein the real power is transferred from the voltage recovery device at a substantially constant voltage for a predetermined period of time.

17. The method of claim 16, wherein, after the predetermined period of time, the real power is transferred from the voltage recovery device at a substantially constant rate.

18. A method of stabilizing a utility power network wherein the utility power network includes a transmission network and a distribution network, the method comprising:

electrically connecting in shunt plural voltage recovery devices, each having an energy storage unit, to the distribution network,

detecting a fault condition on the utility power network; and

operating, in response to detecting the fault condition, the voltage recovery devices to transfer real power and reactive power to the utility power network at a level and for a duration to recover the voltage on the transmission network to within a predetermined proportion of a nominal voltage.

19. The method of claim 18 wherein operating one or more of the voltage recovery devices such that the transfer of real power and reactive power to the utility power network in aggregate is at a level and for a duration to recover the voltage on the transmission network to within a predetermined proportion of a nominal voltage.

20. The method of claim 18 further comprising electrically connecting each of the plural voltage recovery devices at line segments of the transmission network having a fault which causes the voltage on the line segment to be less than 90% of the nominal voltage.

21. The method of claim 19 further comprising electrically connecting each of the plural voltage recovery devices at line segments of the transmission network having a fault which causes the voltage on the line segment to be less than 90% of the nominal voltage.

22. A utility power network comprising:

a transmission line network carrying a nominal voltage;

a plurality of distribution line networks, each connected to the transmission line network, each of the distribution line networks carrying a distribution voltage less than the nominal voltage on the transmission line network; and

a plurality of voltage recovery devices, each connected in shunt to at least one of the distribution line networks, and each of the plurality of voltage recovery devices is configured to transfer real and reactive power between the distribution line network and the voltage recovery device at a level and for a duration to recover the voltage on the utility power network to within a predetermined proportion of the nominal voltage of the transmission line network, following a fault condition detected on the utility power network.

23. The utility power network of claim 22 wherein each of the voltage recovery devices is configured to transfer a combination of real and reactive power.

24. The utility power network of claim 23 wherein each of the voltage recovery device is configured to provide real and reactive power to the utility power network to within 0.90 P.U. of the nominal voltage within 0.5 seconds.

25. The utility power network of claim 23 wherein each of the voltage recovery device comprises:

an inverter electrically coupled between the energy storage unit and one of the distribution line networks; and

a controller connected to the inverter and configured to control the amount of real and reactive power transferred between the energy storage unit and utility power network.

26. The utility power network of claim 25 wherein the energy storage unit includes a superconducting magnet.

27. The utility power network of claim 22 wherein each of the voltage recovery devices is configured to transfer real power and reactive power to the utility power network in aggregate is at a level and for a duration to recover the voltage on the transmission network to within a predetermined proportion of a nominal voltage.

28. The utility power network of claim 22 wherein each of the plural voltage recovery devices is connected at line segments of the transmission network having a fault which causes the voltage on the line segment to be less than 90% of the nominal voltage.

29. The utility power network of claim 27 wherein each of the plural voltage recovery devices is connected at line segments of the transmission network having a fault which causes the voltage on the line segment to be less than 90% of the nominal voltage.