METHOD AND DEVICE FOR ASSESSING AND MONITORING VOLTAGE SECURITY IN A POWER SYSTEM

• US 20090085407A1
• Filed: 09/26/2008
• Published: 04/02/2009
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: Schweitzer Engineering Laboratories, Incorporated
• Inventors: Venkatasubramanian, Vaithianathan
• Granted Patent: US 8,498,832 B2
• Time in Patent Office: Days
• US Class Current: 307/98
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power

Abstract

Provided is a method and device for assessing and monitoring voltage security in a power system. More specifically, a method and device for assessing and monitoring the value of reactive power load when changes in reactive power outputs of at least some of the generators in the electrical power system cause all of the generators in the system to reach the combined operating limit of their reactive power output. In response thereto, the method and device are further adapted to initiate suitable control measures such as switching of transformer banks and/or capacitor/reactor banks, as well as shedding loads whenever necessary to mitigate an impending voltage stability problem.

Claims

1. A device for assessing and monitoring voltage stability in an electrical power system including a plurality of generators and phasor measurement units, said phasor measurement units adapted to acquire and communicate phasor measurements from various locations on the power system, the device comprising:

a communications port adapted to receive the phasor measurements from the phasor measurement units,

a reactive power loading margin calculator adapted to calculate a reactive power loading margin based on the phasor measurements acquired at some of the locations of the phasor measurement units, and

a predictive reactive power load limit calculator adapted to calculate the value of reactive power load when changes in reactive power outputs of at least some of the generators in the electrical power system cause the plurality of generators to reach the combined operating limit of their reactive power output.

2. The device of claim 1 further comprising an apparatus for reducing the reactive power load at one or more of the generators.

3. The device of claim 2 wherein the apparatus is a load shedding apparatus.

4. The device of claim 1 further comprising an apparatus for increasing or decreasing reactive power outputs of some of the generators.

5. The device of claim 1 further comprising an apparatus for accelerating the calculation processing of the reactive power margin calculator.

6. The device of claim 1 further including a generator reactive power sensitivity calculator.

7. The device of claim 6 wherein the generator reactive power sensitivity calculator is based at least in part on power-flow Jacobian.

8. The device of claim 1 further comprising an alarm coupled to the predictive reactive power load limit calculator adapted to indicate when a plurality of generators in the electrical power system have reached their combined maximum operating limit of providing reactive power.

9. The device of claim 1 further comprising a signaling circuit coupled to the predictive reactive power load limit calculator adapted to provide a signal representative of a control or monitoring action when a plurality of generators in the electrical power system have reached their combined maximum operating limit of providing reactive power.

10. The device of claim 1 wherein the communications port is adapted to receive SCADA measurements, and the reactive power loading margin calculator is adapted to calculate a reactive power loading margin based in part on the SCADA measurements.

11. A method for assessing and monitoring voltage stability in an electrical power system including a plurality of generators, including the steps of:

acquiring phasor or SCADA measurements from various locations on the power system,

calculating a reactive power loading margin based on the acquired measurements, and

calculating the value of reactive power load when changes in reactive power outputs of at least some of the generators in the electrical power system cause the plurality of generators to reach the combined operating limit of their reactive power output.

12. The method of claim 11 further comprising the step of reducing the reactive power load at one or more of the generators.

13. The method of claim 11 further comprising the step of increasing the reactive power outputs of some of the generators.

14. The method of claim 11 further comprising the step of decreasing the reactive power outputs of some of the generators.

15. The method of claim 11 further comprising the step of calculating the reactive power sensitivity.

16. The method of claim 15 wherein the generator reactive power sensitivity is calculated based at least in part on power-flow Jacobian.

17. The method of claim 11 further comprising the step of signaling an alarm to indicate when a plurality of generators in the electrical power system have reached their combined maximum operating limit of providing reactive power.