Research On Fault Identification And Ranging Method Of HVDC Transmission Line Based On Transient Traveling Wave

HVDC power transmission system occupies an important position in the field of power transmission due to its advantages of simple transmission model,large transmission power,long transmission distance and good performance.The reliability of its operation is not only related to the safe operation of the internal equipment of the system,but also related to the stable development of the entire power grid system.According to the latest data,the main fault type of HVDC transmission system is line fault.Once a line fault occurs in the HVDC transmission system,the rapid identification and accurate positioning of the fault location is of great significance to the stable and safe operation of the entire system.Therefore,the main research content of this article is:First,use the electromagnetic simulation transient software PSCAD/EMTDC to build a voltage level bipolar HVDC power transmission system simulation model.The simulation model simulates the corresponding current and voltage transient waveforms under normal and line fault conditions.Meet the actual engineering situation.Secondly,use the built simulation model to perform fault simulation experiments on different locations on the transmission line,analyze the directional polarity of the fault voltage and current transient traveling wave generated at the fault point,and then use the directional polarity of the fault current transient traveling wave,Combined with the transient energy deviation coefficient,identify the location of the fault point on the transmission line.Finally,it is based on the identification that the fault location occurred on the HVDC transmission line.The collected current transient traveling wave is imported into MATLAB,and the phase-mode transformation is performed on it to obtain the linear mode component that is not easily affected by the earth factor.Then,the Db4 wavelet transform is performed on the line mode component of the fault current transient traveling wave to decompose the singular points in the traveling wave,and extract the maximum value of the modulus to determine the moment when the transient traveling wave head propagates to the ports on both sides of the line,and finally substitute it In the calculation formula of the traditional traveling wave distance measurement method and the traveling wave distance measurement method without wave speed influence,the accurate fault point distance is obtained,and the two transient traveling wave fault location methods are compared,and the results show that there is no wave speed influence The accuracy and high resistance of the traveling wave ranging method are higher than the traditional traveling wave ranging method.