Research on specialties for 1000kV UHV AC transmission line relaying

摘要

AC 1000kV Ultra-high voltage (UHV) transmission line will be the main frame of power network in China. Comparing to normal voltage class and EHV (Extra-high voltage) transmission line, UHV line has specialties of its electric parameters and operating characteristics. UHV 1000KV line has more distributed capacitance, longer distance and larger proportion of reactance and resistance, which results in obvious transient state while fault loading or operating; 1000kV line has more distributed capacitance, longer distance, more obvious distributed parameter state, which may make influence to extent distance relay’s theoretical basis; 1000kV line may has more capacitance current whether in transient state or steady state, which will make influence to split-phase differential protection. These characters of UHV transmission line may make affection on existing protection relay. This paper analyses the characters of fault transient process, connecting unloaded line, and discusses their influence on UHV transmission line protection to help developing protection relay device.