Method for preventing power collapse in electric power systems

• US 5,642,000 A
• Filed: 05/03/1993
• Issued: 06/24/1997
• Est. Priority Date: 05/03/1993
• Status: Expired due to Term

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Jean-Jumeau, Rene, Chiang, Hsiao-Dong
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): GANJIAN, PETER
• Application Number:
  US08/055,334
• Time in Patent Office: 1,513 Days
• Field of Search: 307/31, 307/66, 307/64, 307/38, 307/39, 363/95, 364/480, 364/491, 364/492, 364/493
• US Class Current: 307/31
• CPC Class Codes: H02J 3/1871 Methods for planning installation of shunt reactive power compensators

Abstract

The present invention features a method for determining a performance index for each power-generating system, directly correlated to load demands. This performance index can be easily interpreted by power engineers and operators, so that weak areas and potential voltage collapse conditions can be predicted and corrected. When the underlying cause of collapse is due to load variations, the performance index of the current invention has the ability to assess the amount of load increase that the system can tolerate prior to such collapse. When the underlying collapse mechanism is due to a contingency, the performance index of this invention can measure its severity. The performance index of this invention can also assess whether the system can sustain a contingency without collapse.

Claims

1. A method of preventing voltage collapse in a power-generating system having a grid comprising a plurality of load buses, comprising the steps of:

a) measuring load flow in the power-generating system having a grid comprising a plurality of load buses;

b) calculating a voltage collapse index (VCI) directly correlated to load demands of the power-generating system of step (a);

c) utilizing the voltage collapse index to identify weak areas in the power-generating system;

d) selecting a cluster of said load buses of said grid identified as weak areas for load variation;

e) determining actual safety margins that exist for these weak areas before collapse will occur; and

f) shedding power in those selected load buses of said grid that are identified as weak areas, in order to prevent voltage collapse in the power-generating system in accordance with said safety margins.

2. The method of preventing voltage collapse in a power-generating system in accordance with claim 1, wherein as part of the calculation of VCI, said method additionally obtains an exact point of voltage collapse (PVC) for the power-generating system.

3. The method of preventing voltage collapse in a power-generating system in accordance with claim 1, wherein as part of the calculation of VCI and safety margins, said method varies reactive power on at least one of a plurality of buses for the power-generating system.

4. The method of preventing voltage collapse in a power-generating system in accordance with claim 3, wherein reactive power is simultaneously varied on at least two of the plurality of buses for the power-generating system.

5. The method of preventing voltage collapse in a power-generating system in accordance with claim 1, further comprising the step of:

f) determining load-sustaining capacities of the weak areas.

6. A method of preventing voltage collapse in a power-generating system having a grid comprising a plurality of load buses, comprising the steps of:

a) measuring the load demands in the power-generating system having a grid comprising a plurality of load buses;

b) calculating a voltage collapse index (VCI) directly correlated to load demands of the power-generating system of step (a);

c) utilizing the voltage collapse index to identify weak areas in the power-generating system;

d) selecting a cluster of said load buses of said grid identified as weak areas for load variation;

e) determining actual safety margins that exist for these weak areas before collapse will occur; and

f) adding power-generating capacity to those selected load buses of said grid that are identified as weak areas of said power-generating system, in order to prevent voltage collapse during heavy load conditions.

7. The method of preventing voltage collapse in a power-generating system in accordance with claim 6, wherein as part of the calculation of VCI, said method additionally obtains an exact point of voltage collapse (PVC) for the power-generating system.

8. The method of preventing voltage collapse in a power-generating system in accordance with claim 6, wherein as part of the calculation of VCI and safety margins, said method varies reactive power on at least one of a plurality of buses for the power-generating system.

9. The method of preventing voltage collapse in a power-generating system in accordance with claim 8, wherein reactive power is simultaneously varied on at least two of said plurality of buses for the power-generating system.

10. The method of preventing voltage collapse in a power-generating system in accordance with claim 6, further comprising the step of:

f) determining load-sustaining capacities of the weak areas.

11. A method of preventing voltage collapse in a power-generating system, comprising the steps of:

a) measuring the load demands in the power-generating system;

b) calculating a voltage collapse index (VCI) directly correlated to load demands of the power-generating system of step a) wherein reactive power is simultaneously varied on at least two of a plurality of buses for the power-generating system; and

c) utilizing the voltage collapse index to prevent power failure in said power-generating system.

12. The method of preventing voltage collapse in a power-generating system in accordance with claim 11, wherein an underlying collapse mechanism of said power-generating system is determined to be due to a contingency, said method further comprising the step of:

d) utilizing the voltage collapse index to measure severity of said contingency.

13. The method of preventing voltage collapse in a power-generating system in accordance with claim 11, wherein an underlying collapse mechanism of said power-generating system is determined to be due to a contingency, said method further comprising the step of:

d) utilizing the voltage collapse index to assess whether the system can sustain a contingency without collapse.

14. The method of preventing voltage collapse in a power-generating system in accordance with claim 11, wherein an underlying collapse mechanism of said power-generating system is determined to be due to load variations, said method further comprising the step of:

d) utilizing the voltage collapse index to assess the amount of load increase that the power-generating system can tolerate prior to such collapse.

15. A method of preventing voltage collapse in a power-generating system, comprising the steps of:

a) measuring the load demands in the power-generating system;

b) calculating a voltage collapse index (VCI) directly correlated to load demands of the power-generating system of step (a) wherein reactive power is varied on at least one of a plurality of buses for the power-generating system; and

c) utilizing the voltage collapse index to prevent power failure in said power-generating system.

16. The method of preventing voltage collapse in a power-generating system in accordance with claim 15, wherein an underlying collapse mechanism of said power-generating system is determined to be due to a contingency, said method further comprising the step of:

d) utilizing the voltage collapse index to measure severity of said contingency.

17. The method of preventing voltage collapse in a power-generating system in accordance with claim 15, wherein an underlying collapse mechanism of said power-generating system is determined to be due to a contingency, said method further comprising the step of:

d) utilizing the voltage collapse index to assess whether the system can sustain a contingency without collapse.

18. The method of preventing voltage collapse in a power-generating system in accordance with claim 15, wherein an underlying collapse mechanism of said power-generating system is determined to be due to load variations, said method further comprising the step of:

d) utilizing the voltage collapse index to assess the amount of load increase that the power-generating system can tolerate prior to such collapse.