Systems and methods for monitoring and controlling electrical system stability
Disclosed herein are systems and methods for monitoring and controlling an electric power delivery system to mitigate against voltage instability. According to various embodiments, one or more stability thresholds may be compared to one or more stability estimates. Stability estimates may be generated based on electrical conditions in an electric power delivery system. Upon the occurrence of the contingency, one or more control actions specified by a contingency index may be executed in order to mitigate against voltage instability. A plurality of stability estimates may be generated, each of which may be compared to a respective stability threshold. According to various embodiments, stability estimates and stability thresholds may be based on a reactive power to voltage margin, an incremental reactive power cost, an incremental load cost, and a power import margin.
1. A method to maintain stability in an electric power delivery system, comprising:
establishing a stability threshold;
receiving a plurality of measurements representing electrical conditions in an electric power delivery system and a plurality of status indicators;
generating a stability estimate based on the plurality of measurements representing electrical conditions;
determining that the stability estimate satisfies the stability threshold;
determining the occurrence of a contingency specified in a contingency index based on the plurality of status indicators, the contingency index comprising a plurality of contingencies and at least one control instruction correlated with each of the plurality of contingencies; and
implementing the at least one control instruction specified by the contingency index based on the stability estimate and correlated with the contingency.
2. The method of claim 1 , further comprising:
representing the plurality of measurements as a plurality of time-synchronized vectors.
3. The method of claim 2 , further comprising:
transmitting the plurality of time-synchronized vectors to a vector processor.
4. The method of claim 3 , further comprising:
generating a packet comprising a plurality of time-synchronized vectors; and
transmitting the packet using the IEEE C37.118 protocol to the vector processor.
5. The method of claim 1 , wherein gathering a plurality of status indicators comprises one of:
monitoring a status of a breaker;
monitoring a tap position of a transformer;
monitoring the status of a reactive power compensator;
monitoring the status of a static VAR compensator; and
monitoring the status of a capacitor bank.
6. The method of claim 1 , wherein gathering the plurality of measurements representing electrical conditions comprises one of:
monitoring a voltage; and
monitoring a current.
7. The method of claim 1 , wherein the stability estimate comprises a reactive power to voltage margin.
8. The method of claim 1 , wherein the stability estimate comprises one of:
an incremental reactive power cost,
an incremental load cost, and
a power import margin.
9. The method of claim 1 , wherein the contingency comprises one or more of:
a disconnection of a transmission line,
a loss of an electrical generator,
a connection of a load,
a disconnection of a transformer, and
a disconnection of a reactive power compensator.
10. The method of claim 1 , wherein the control action comprises one of:
shedding a selected load,
increasing power generation, and
connecting a reactive power compensator.
11. The method of claim 1 , further comprising:
identifying two redundant measurements from among the plurality of measurements representing electrical conditions;
calculating a mean value of the two redundant measurements; and
replacing the two redundant measurements with the mean value of the two redundant measurements.
12. The method of claim 1 , further comprising:
updating a network model of the electric power delivery system;
simulating a plurality of scenarios using the network model, the plurality of measurements representing electrical conditions, and the plurality of status indicators; and
generating the stability estimates based on the simulation of the plurality of scenarios.
13. The method of claim 1 , further comprising:
transmitting at least one of the stability threshold, the stability estimate, and the control instruction to one of a SCADA system and a wide-area situational control and awareness system.
14. The method of claim 1 , further comprising:
delaying the execution of a control action by a specified time period.
15. A voltage stability system, comprising:
a measurement receiving subsystem to receive a plurality of measurements representing electrical conditions in an electric power delivery system and a plurality of status indicators;
a stability assessment subsystem to generate a stability estimate based on the plurality of measurements and to compare the stability estimate to a stability threshold to determine that the stability estimate satisfies the stability threshold;
a contingency assessment subsystem comprising a contingency index, the contingency index comprising a plurality of contingencies and at least one control instruction correlated with each of the plurality of contingencies, the contingency assessment subsystem configured to determine the occurrence of a contingency based on the plurality of status indicators; and
an automatic control subsystem to implement the at least one control action specified by the contingency index based on the stability estimate and correlated with the contingency.
16. The system of claim 15 , wherein the measurement receiving subsystem further comprises:
a time-alignment subsystem to time align a plurality of time-synchronized measurements from the plurality of measurements.
17. The system of claim 16 , wherein the time-alignment subsystem is configured to receive the plurality of measurements from a plurality of phasor measurement units.
18. The system of claim 16 , wherein the time alignment subsystem further comprises a real-time vector processor.
19. The system of claim 15 , further comprising a network model simulation subsystem to simulate a plurality of scenarios using a network model, the plurality of measurements, and the plurality of status indicators and to generate the stability estimate based on the simulation of the plurality of scenarios.
20. The system of claim 15 , further comprising a timer to delay the execution of a control action by a specified time period.
21. The system of claim 15 , further comprising a reporting subsystem to transmit at least one of the stability threshold, the stability estimate, and the control instruction to one of a SCADA system and a wide-area situational control and awareness system.
22. An IED, comprising:
a processor; and
a non-transitory computer-readable storage medium, comprising:
a measurement receiving module executable on the processor to receive a plurality of measurements representing electrical conditions in an electric power delivery system;
a stability assessment module executable on the processor to generate a stability estimate based on the plurality of measurements and to compare the stability estimate to a stability threshold to determine that the stability estimate satisfies the stability threshold;
a contingency assessment module executable on the processor comprising a contingency index, the contingency index comprising a plurality of contingencies and at least one control instruction correlated with each of the plurality of contingencies, the contingency assessment module configured to determine the occurrence of a contingency based on the plurality of status indicators; and
an automatic control subsystem module executable on the processor to implement the at least one control action specified by the contingency index based on the stability estimate and correlated with the contingency.