Simulation study of overvoltage in UHV AC and DC hybrid system

Based on Yunnan-Guangdong ± 800kV special high pressure DC transmission system of engineering parameter, we will research Two-phase grounding short circuit in converter transformer secondary side of inverter side of ultra-high voltage DC system and Single-phase grounding fault and reclosing in Ultra-high voltage(UHV) AC system in the UHV AC-DC hybrid system and the effects between AC and DC system when the fault happened. For the research of overvoltage we use MATLAB/Simulink simulation software established the model of UHV AC-DC system, then simulate some type overvoltage caused by different type of AC or DC fault. Simulation results show that AC or DC fault of UHV AC and DC hybrid system occurs not only in the AC and DC overvoltage caused by AC and DC systems, overvoltage will obviously influence each other, causing the system voltage more diversified.