Wide Area Protection Scheme Preventing Cascading Events based on Improved Impedance relay

Load flow transferring after an initial contingency is regarded as one of the main reasons of causing unexpected cascading trips. A multi agent system (MAS) based wide area protection strategy is proposed in this paper to predict the load flow transferring from the point of view of impedance relays, and prevent the unexpected relay operations accordingly. The variations of node injections during the post fault transient period will be also considered in the prediction algorithm. The power system of Eastern Denmark modeled in real time digital simulator (RTDS) will be used to demonstrate the proposed strategy. The simulation results indicate this strategy can successfully predict and prevent the unexpected relay operation caused by load flow transferring.