The Research Of The Protection And Its Application In 750kV Power System

With the development of power technology and continuing to investigate to electric fence relay protection, electric fence relay protection has become maturated.As the first line of defence of electric fence relay protection operating safely, relay protection play an important part all the time.So this paper lay stress on 750kV system circuit after realizing the importance of relay protection.This paper takes 750kV substation in Guan Ting and Lan Zhou as object of study.According to the system related paraments provided by Northwest Power Grid Company and the results from the dynamic provided by power Research Institute,this paper analyzes the electric current varies besides the circuit and the transient state process caused by distributed capacitance when circuit is shorted.And it also analyzes the higher-order of oscillation.On this basis,this paper also analyzes value of DC decay copponent when short circuit occur and the difference AC decay copponent besides the circuit.At last,this paper introduces the characteristics of static exciter and over exciter,studys the measures of static exciter and over exciter.Through the analysis of the capacitance current,transient process of interim resistance,feeder,heavy load,unload charge and large short-circuit current in the circuit protection of 750kV UHV transmission lines. Some help and guidance for research and development on protection device of UHV transmission lines are provided.