Research On Lightning Interference Identification Of Hvdc Transmission Line

In recent years,China High Voltage Direct Current(HVDC)transmission project has ushered in a blowout development,HVDC transmission is in a key position in today power development,so it is very important to ensure the safe and stable operation of HVDC transmission lines.At present,traveling wave protection and transient protection are widely used in the main protection of HVDC transmission lines,which are vulnerable to the influence of high frequency signals in lightning current,causing protection misoperation and even affecting the stable operation of the whole HVDC transmission system.Therefore,in order to effectively reduce the probability of DC line protection maloperation under lightning interference and improve the reliability of protection,it is very important to study the lightning interference identification method of DC transmission line.This paper focuses on the research of lightning interference identification of HVDC transmission lines.(1)The electromagnetic transient simulation model of HVDC transmission system is established to realize the electromagnetic transient simulation of different types of lightning fault and lightning disturbance.Aiming at different lightning fault and lightning disturbance,the transient characteristics and fault mechanism are analyzed in depth and systematically,and the waveform variation rules of transient voltage and current under different conditions are summarized.(2)Based on the characteristic difference of voltage time-domain waveforms in the case of lightning fault and lightning disturbance,the voltage deviation degree is defined by referring to the concept of goodness of fit in statistics.The principle of lightning disturbance identification of HVDC transmission line based on voltage deviation degree is proposed,and the corresponding judgment and algorithm are designed.A large number of simulation results show that the method can effectively distinguish the line lightning disturbance,the line lightning disturbance and the line lightning disturbance The distinguishing principle is clear,the calculation is simple,and the distinguishing effect is not affected by the fault distance and lightning current waveform.(3)Based on the characteristic difference between lightning fault and lightning disturbance in frequency domain,the principle of lightning disturbance identification for HVDC transmission line based on EMD decomposition is proposed,and the algorithm flow is given.This method extracts the average value of the variation amplitude of the low-frequency voltage component after the occurrence of lightning as the benchmark for distinguishing lightning fault and lightning interference.A large number of simulation tests verify the effectiveness of the method,and the method is not affected by the fault distance and lightning current waveform,and can be used when the sampling frequency is more than 20 kHz.In this paper,the lightning interference identification methods for HVDC transmission lines are proposed.They consider the types of lightning comprehensively,have high accuracy,and their threshold values are clear.They can realize the distinction between lightning single pole fault and lightning double pole fault.