Centralized Load Shedding Based on Thermal Limit of Transmission Lines Against Cascading Events

Load shedding is the last and most expensive control action against system collapse and blackout. Achievement of an efficient emergency control to stabilize the power system following severe disturbances, requires two key objectives. First, preventing of further cascading outages, i.e. saving the available and determinant power system elements and second, issuing proper control actions to stabilize the power system inside the permissible time frame. In this paper online contingency analysis is performed to monitor secure and reliable operation of transmission lines. Load shedding locations are continuously updated based on loading rate/thermal limit of lines to prevent their outage. Simulation of severe contingencies carried out on 39 bus IEEE standard test system in DIgSILENT power-factory validates the efficiency of proposed method.