The Research Of Distribution Network Fault Protection Of A New Type Of Grounding Method Using Peterson-coil Paralleling Resistor

With the urbanization of China,distribution network develops very fast in recent years.Power distribution system have features of wide area,complex structure and frequent random failures.The grounding modes of neutral point influence on the safe and stable operation of the distribution network,but it has been a subject of controversy at home and abroad.This paper proposes a new distribution network grounding method,which is able to solve the problem of arc extinction and fast trip at the same time.This new grounding method is mainly consist of arc suppression coil and controllable parallel resistor,whose main advantages are as follow: When the grid single-phase ground fault occurs,the arc suppression coil suppress the arc immediately.If the fault evolved into a permanent failure,input parallel resistance,suppress the fault recovery phase voltage effectively and avoid arcing renewed.The inputted resistance can provide active component for the fast trip.Once the faulty line is selected,cut the parallel resistor and the grid go on working.This paper firstly analyzed the basic principle of the new grounding method,including the transient and steady-state analysis of transient fault and permanent fault,and verified the feasibility through simulation.Secondly,some key issues are discussed in a detailed theoretical study and simulation,including the analysis of the relationship between parallel resistor and system parameters,the transient current impulse caused by the switching of parallel resistor,and the parallel resistor input time on arc grounding overvoltage influence.Then we studied the protection mechanism of the new grounding method,and proposed the fault protection setting programs and integrated line-selection schemes,which is able to improve the accuracy of fault detection.Finally,the overall program design and calculation of a 110 kV substation's 10 kV bus side via the new grounding method is done.The new grounding method combines the function of ‘fast arc suppression' and ‘fast line-selection'.It has the advantages of the traditional grounding methods and avoided the shortcomings of them.Simulations verified the new grounding method is able to realize fast fault-line selection on the basis of fast arc suppression,and can reduce outage time,reduce security risks,and ensure the safety and stable operation of the power system.