The Analysis And Improvement Of Microcomputer Protection Operation Performance In The 35kV Qianqi Substation

Substation is an important part of power system.It plays an important role in energy transmission and voltage conversion in the whole power system.Its safe operation is related to the continuous and stable work of the whole power system.Relay protection is an important measure to realize the safe operation of substation.Differential protection,as the main protection of transformer,is widely used in substations over 35 k V.However,due to unbalanced current such as inrush current,the differential protection may malfunction,resulting in the outage of the whole substation.The load transfer and other automatic devices not only increase the risk of power grid operation but also it can cause overload of another main transformer.This paper begins with the overview of relay protection,the development trend of relay protection at home and abroad is analyzed.Taking the Qianqi substations of 35 k V as an example,the composition and operation mechanism of microprocessor-based protection system are introduced.Then,the principles and configuration of line and main transformer protection are introduced respectively.Secondly,the substation line is simulated in the background of a line accident,and the change rule of three-phase current under the condition of fault is obtained,and the improvement suggestions for the existing problems of protection are put forward.Based on the simulation of inrush current and differential protection with harmonic braking,the causes and preventive measures of differential protection maloperation are studied.In view of the line and main transformer accidents of the station,the existing problems of differential protection of the station are analyzed,and the problems exposed in the performance of differential protection are put forward in combination with the summary of inrush differential accidents.Specific improvement and preventive measures are put forward from three aspects: human factors,technical factors and management factors,so as to solve the errors of differential protection of the station.