Adaptive Islanding Demonstration in the Western Electricity Coordinating Council

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This project developed an integrated algorithm to identify a cutset for a large power system for the application of a slow coherency based controlled islanding scheme. Controlled islanding is employed as a corrective measure of last resort to prevent cascading outages caused by large disturbances. The large scale power system is represented as a graph and a simplification algorithm is used to reduce the complexity of the system. Generators belonging to the same slowly coherent group are collapsed into a dummy node, and a graph partition library is used to split the graph into a given number of parts. Some extra islands formed by the partition library are merged into their adjacent large islands and the original cutset of the actual power system is recovered from the highly simplified graph.  

A software package was developed to test the efficiency of the algorithm, and dynamic simulations were run on the WECC system to verify the effectiveness of the cutset obtained. To test the islanding performance, four extreme contingencies under two different operating conditions of the WECC system are tested using time domain simulations. Time domain simulation results for the four contingencies with controlled islanding and uncontrolled islanding are shown, and the dynamic performance in each case is analyzed. Further analyses are conducted to examine the amount of load shed in each case, and a discussion of the cutset sensitivity and time sensitivity of islanding are provided.

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