Synchrophasor monitoring of single line outages via area angle and susceptance

The area angle is a scalar measure of power system area stress that responds to line outages within the area and is a combination of synchrophasor measurements of voltage angles around the border of the area. Both idealized and practical examples are given to show that the variation of the area angle for single line outages can be approximately related to changes in the overall susceptance of the area and the line outage severity.Comment: adjusted version accepted at North American Power Symposium (NAPS), Pullman WA USA, September 201

Monitoring of single and multiple line outages with synchrophasors in areas of the power system

When power grids are heavily stressed with a bulk power transfer, it is useful to have a fast indication of the increased stress when multiple line outages occur. Reducing the bulk power transfer when the outages are severe could forestall further cascading of the outages. Phasor measurement units (PMUs) are vital elements for monitoring and control of these heavily stressed power system. This work presents a new approach to implement and utilize PMU information to monitor operational transfer capability and limits based on voltage phasor angles with respect to thermal limits of transmission lines. This work demonstrates an algorithm to obtain thresholds based on the angle and then quickly deploy PMU data to monitor stress changes due to single and multiple outages in real time to send fast notification of emergency situations. Area angle uses the topology and the synchronized measurements of angles across an area of power system to measure stress caused by outages within the area. The proposed algorithm is easy, quick and computationally suitable for real systems to capture bulk stress caused by outages and also identify local stress. This work first illustrates the idea of area angle in a Japanese test system and then explores the choice of the border buses. It further investigates the relation between area angle to area susceptance and supports the findings in two areas of the Western North American power system. Finally, this work develops a procedure to define thresholds for the area angle that relate to the maximum power that can be transferred through the area until a line limit is reached. The algorithm finding the area angle thresholds offline and then in real time monitoring the area angle and comparing it to the thresholds after multiple outages determines the urgency (or not) of actions to reduce the bulk transfer of power through the area. The procedure also identifies exceptional cases in which separate actions to resolve local power distribution problems are needed. The findings are supported by testing on a 1553 bus reduced model of the Western interconnection power system

Voltage Control Performance Evaluation using Synchrophasor Data

With increasing availability of synchrophasor technology, enabled by phasor measurement units (PMUs), applications based on this technology are being implemented as a practical approach for power systems monitoring and control. While synchrophasor data provides significant advantages over SCADA data it has limitations, especially in the area of model validation and estimation. With the increasing complexity of the power system, the need for equipment monitoring and performance evaluation becomes more relevant, traditionally model validation and estimation process can be used to look at control equipment performance. However, due to the challenges associated with these processes there are limitations on the performance evaluation. This work introduces am improved signal-processing based algorithm to monitor control system performance during disturbance events in the power system and during ambient conditions, or normal power system operation, additionally the algorithm is demonstrated on data obtained from the interconnection point of a STATCOM device and a synchronous generator during ambient and disturbance operation

Monitoring of single and multiple line outages with synchrophasors in areas of the power system

When power grids are heavily stressed with a bulk power transfer, it is useful to have a fast indication of the increased stress when multiple line outages occur. Reducing the bulk power transfer when the outages are severe could forestall further cascading of the outages. Phasor measurement units (PMUs) are vital elements for monitoring and control of these heavily stressed power system. This work presents a new approach to implement and utilize PMU information to monitor operational transfer capability and limits based on voltage phasor angles with respect to thermal limits of transmission lines. This work demonstrates an algorithm to obtain thresholds based on the angle and then quickly deploy PMU data to monitor stress changes due to single and multiple outages in real time to send fast notification of emergency situations. Area angle uses the topology and the synchronized measurements of angles across an area of power system to measure stress caused by outages within the area. The proposed algorithm is easy, quick and computationally suitable for real systems to capture bulk stress caused by outages and also identify local stress. This work first illustrates the idea of area angle in a Japanese test system and then explores the choice of the border buses. It further investigates the relation between area angle to area susceptance and supports the findings in two areas of the Western North American power system. Finally, this work develops a procedure to define thresholds for the area angle that relate to the maximum power that can be transferred through the area until a line limit is reached. The algorithm finding the area angle thresholds offline and then in real time monitoring the area angle and comparing it to the thresholds after multiple outages determines the urgency (or not) of actions to reduce the bulk transfer of power through the area. The procedure also identifies exceptional cases in which separate actions to resolve local power distribution problems are needed. The findings are supported by testing on a 1553 bus reduced model of the Western interconnection power system.</p

Area angle can monitor cascading outages with synchrophasors

We monitor the severity of multiple line outages inside an area of the power system according to the limitations on a bulk power transfer through the area when the outages occur. The monitoring combines together synchrophasor measurements around the border of the area to form an angle across the area that can be tracked in real time. This is an approach based on physical principles to extract actionable information by suitably combining synchrophasor measurements. We show the capabilities of the method on a model of the WECC system on an area with approximately 500 lines.This is a manuscript of a proceeding published as Darvishi, Atena, and Ian Dobson. "Area angle can monitor cascading outages with synchrophasors." In Innovative Smart Grid Technologies Conference (ISGT), 2015 IEEE Power & Energy Society, pp. 1-5. IEEE, 2015. 10.1109/ISGT.2015.7131778. Posted with permission.</p

Threshold-Based Monitoring of Multiple Outages With PMU Measurements of Area Angle

When power grids are heavily stressed with a bulk power transfer, it is useful to have a fast indication of the increased stress when multiple line outages occur. Reducing the bulk power transfer when the outages are severe could forestall further cascading of the outages. We show that synchrophasor measurements of voltage angles at all the area tie lines can be used to indicate the severity of multiple outages. These synchrophasor measurements are readily combined into an “area angle” that can quickly track the severity of multiple outages after they occur. We present a procedure to define thresholds for the area angle that relate to the maximum power that can be transferred through the area until a line limit is reached. Then in real time we would monitor the area angle and compare it to the thresholds when line outages occur to determine the urgency (or not) of actions to reduce the bulk transfer of power through the area. The procedure also identifies exceptional cases in which separate actions to resolve local power distribution problems are needed. We illustrate the thresholds and monitoring with the area angle across several states of Northwestern USA.This is a manuscript of an article published as Darvishi, Atena, and Ian Dobson. "Threshold-based monitoring of multiple outages with PMU measurements of area angle." IEEE Transactions on Power Systems 31, no. 3 (2016): 2116-2124. doi: 10.1109/TPWRS.2015.2454517. Posted with permission.</p