Investigation of Receiving-End Commutation Failures in Multi-infeed HVDC Systems via Real Time Digital Simulation

High Voltage Direct Current (HVDC) transmission technology has been widely applied in long-distance power transmission and large-scale grid interconnections due to its unique technical and economic advantages. Commutation failure, one of the most common faults in HVDC systems, may lead to adverse consequences such as DC voltage reduction, lifecycle reduction of converter valves, DC Magnetic bias in converter transformers, and overvoltage in weak AC systems on the receiving-end side. In severe cases, it can trigger sequential commutation failures or even DC block, critically affecting the security and stability of the entire power system. This paper employs a closed-loop real-time simulation system integrating the control and protection equipment of three actual HVDC systems (Baijiang, Hazheng, and Xiangshang projects) and a Real-Time Digital Simulation System (RTDS). Through single-phase grounding fault tests on the receiving-end AC system of the three-interconnected HVDC system, the commutation failure characteristics and recovery mechanisms are investigated.