Electromechanical-electromagnetic Transient Hybrid Simulation Research on AC Fault Ride-through Characteristics at Receiving-end of LCC-VSC Hybrid Cascaded DC System

Line commutated converter-voltage source converter (LCC-VSC) hybrid cascaded DC system combines the advantages of LCC and VSC. The topology structure that the rectified side adopts LCC, and the inverse side adopts LCC connected by VSC groups shows the advantages of large-capacity power transmission. Based on advanced digital power system simulator (ADPSS), the electromechanical-electromagnetic transient hybrid simulation model of large power grid containing LCC-VSC hybrid cascaded DC is set up, and the research on characteristics of AC fault ride-through at receiving-end is carried out, which takes into account simulation accuracy and scale. The results show that compared with the electromagnetic transient simulation using equivalent network, the hybrid simulation can more accurately simulate the voltage drop and recovery characteristics of AC system, and verify the necessity of using this simulation method. The research of ride-through characteristics needs to focus on the scene where only two VSCs are in operation at either of the two poles and comprehensively consider the faults in the nearby areas around DC drop point. The spinning reserve proportion and inductive motor proportion in load in the nearby areas around DC drop point are strongly related to the recovery characteristics of AC voltage, which are two important factors affecting the ride-through characteristics of AC fault at receiving-end.