Research On Voltage Sag Source Location Method Based On Fault Component Power Characteristics

Voltage sags affect the power quality of the power supply and cause serious economic losses.This problem also will cause economic disputes between the power supplier and the electricity user.The accurate location of voltage sag source is not only important for judging the relative position of voltage sag source in the system,but also important for the safety and economic operation of power system.In this paper,the location of voltage sags that caused by short circuit faults is studied.A kind of voltage sag source location method based on fault component power is proposed.The superposition theorem of linear circuit is applied,then the fault network decomposes into a steady state network and a fault component network,and the characteristics of the instantaneous power of the fault component network analyzed.If the monitoring instantaneous power of fault component is positive,the voltage sag source is located at the upstream of the monitoring device;otherwise,if the monitoring instantaneous power of fault component is negative,the voltage sag source is located at the downstream of the monitoring device.This method is mainly using for voltage sags caused by symmetrical faults.In order to solve the location of the asymmetric voltage sag,this paper uses the improved instantaneous symmetrical component method,the fault component network is decomposed into fault component of positive sequence,negative sequence and zero sequence network;then the definition of fault component sequence power is given,the characteristics of fault component sequence power are analyzed.A kind of location is proposed that based on the fault component sequence power of the voltage sag source.If the monitoring instantaneous positive(negative)sequence power of fault component is positive,the voltage sag source is located at the upstream of the monitoring device;otherwise,if the monitoring instantaneous positive(negative)sequence power of fault component is negative,the voltage sag source is located at the downstream of the monitoring device.This method can effectively locate the voltage sags caused by asymmetric faults and symmetrical faults.The scheme for the location of the voltage sag source is studied.According to the two kind of the methods,the method of the fault component power with smaller computational complexity is used to locate symmetrical sags,and the fault sequence power method is used to locate the asymmetric sags.The location scheme can realize the location of voltage sags source accurately and rapidly.A model of dual power supply system is built by MATLAB/Simulink and the simulation analysis of different fault points and various short circuit types is carried out.The simulation results show that the proposed scheme can effectively locate the voltage sags caused by symmetrical faults and asymmetrical faults,and the positioning accuracy is high.