Real-Time Analysis of Power System Protection Schemes Using Synchronized Data

An error in a power system protection scheme can result in unwanted tripping of healthy lines or delay in the removal of a fault from the network, thus affecting the power system stability. Online identification of such an error provides scope to initiate remedial measures, thereby preventing possible cascade tripping situations. In this paper, a method for real-time analysis of protection decision in a power system is proposed. This method identifies the relay, which has maloperated for an event in the network. For analysis of a relay operation, synchrophasor data from selected locations are obtained depending on the network topology. A function is developed utilizing indices calculated from the synchronized data. Based on the calculated value of the function during an event, the correctness of the protection decision is validated. Results obtained from PSCAD/EMTDC simulations for the New England 39-bus system demonstrate the performance of the proposed method.