Trajectory Sensitivity Based Voltage Stability Constrained Reactive Optimal Power Flow in Sending-End Power System with High Penetration Renewable Energy

With the increasing scale of photovoltaic (PV) plants in Qinghai UHVDC sending-end power grid, short-term voltage stability problems after large disturbances should be paid more attention. A reactive optimal power flow (ROPF) model considering short-term voltage stability constraints is proposed in this paper. Synchronous condenser (SC) is used as one of control means to improve voltage stability. Firstly, transient overvoltage phenomenon and reasons of DC commutation failure process are presented. The impact of the allocation of SCs on reducing transient overvoltage is analyzed. Secondly, to prevent PV plants from tripping caused by transient overvoltage, short-term voltage stability constraints are given according to the high-voltage ride through (HVRT) requirement of PV plants. Then these constraints are linearized based on trajectory sensitivity and incorporated into ROPF model. Finally, simulation results based on Qinghai power grid show the effectiveness of the proposed model.