Comparative Study on Different Temporary Blocking Schemes of Valve Control in VSC-HVDC System

Abstract

To improve the fault ride-through capability of the VSC-HVDC system and ensure the safe operation of the equipment, it is necessary to design the temporary blocking scheme of the converter valve of VSC-HVDC. Taking the Chongqing Hubei Back to Back VSC-HVDC Project as the research object, this paper first analyzes the fault types of the VSC-HVDC system, obtains the fault types of the AC fault ride-through; and then, according to the requirements of system fault ride-through, three-valve controlled temporary blocking schemes are designed: global blocking, phase splitting blocking and bridge arm separated blocking. Finally, based on the RTDS real-time simulation platform, the actual valve control and control protection systems are connected. Comparative simulation tests are carried out to verify the three temporary blocking schemes. The simulation results show that the bridge arm separated blocking can ensure the fault-passing ability of the converter valve and has good electrical characteristics. In practical projects, the bridge arm separated blocking scheme is recommended for valve-controlled bridge arm overcurrent protection.