Load shedding method aimed fast voltage recovery to prevent interference of FIDVR with UV relays

The fault-induced delayed voltage recovery (FIDVR) and short-term voltage instability (STVI) phenomena appear in networks with high penetration of induction motor loads because the increase in requested reactive powers of these loads prevents the voltages from quickly returning to their pre-fault levels. Load shedding (LS) is one of the ways to deal with FIDVR and STVI and reduce the imbalance between the generation and demand of reactive power. Under-voltage (UV) relays that disconnect loads during voltage drop cannot effectively deal with this phenomenon because of their inability to detect the effective loads on the reduction of FIDVR and STVI severities. Therefore, the operation of UV relays during these phenomena causes unnecessary load disconnection, and the interference of their operations with FIDVR and STVI must be avoided. This paper presents two wide-area approaches based on network and loads parameters, the first of which deals with the most critical FIDVR, and the second tries to simultaneously handle critical FIDVRs of all buses. Also, bus prioritization for LS during STVI has been addressed. Simulation results revealed the better performance of the proposed approaches than the previous ones in terms of the amount of LS and the number of selected buses for LS.