Traveling Wave Fault Location Of High-voltage DC Transmission Lines Based On AVMD And SWT

With the rapid development of modern power transmission technology,HVDC transmission plays an important role in long-distance and large-capacity transmission.Due to the long distance of the transmission line,and complicated and variable environment along the line,the probability of failure is high.Once the transmission line fails,the fault point is difficult to find.Therefore,the development of fault location technology for HVDC transmission lines is of great significance for restoring system power supply,reducing power outage losses,and improving the stability and economy of power system operations.In order to accurately and reliably perform fault location of HVDC transmission lines,the generation and propagation characteristics of fault traveling waves and factors affecting the accuracy of traveling wave method are systematically studied.Comparing several commonly used detection algorithms and their advantages and disadvantages,it is proposed to introduce variational mode decomposition(VMD)into the fault location of HVDC transmission lines.Aiming at the problem that the number of decomposition modes K and the quadratic penalty factor ? are not clearly selected,an adaptive variational mode decomposition(AVMD)is given.Continuous wavelet transform is used to determine the number K of modal components in the process of VMD decomposition.By calculating the pearson correlation coefficient and a large number of experiments,the best value of ? is obtained.The fault traveling wave signal is decomposed by AVMD to obtain several inherent modal components.Select the mode containing the fault feature information,and perform time-frequency analysis by synchrosqueezing wavelet transform(SWT)to calibrate the location of the mutation point and obtain the time when the fault traveling wave reaches the rectifier side and inverter side.The fault distance is calculated by using the double-end ranging principle to achieve accurate fault location of the HVDC transmission line.Build a HVDC transmission line fault simulation system model in PSCAD / EMTDC,and verify the fault traveling wave location method of high-voltage DC transmission line based on AVMD and SWT.The simulation results show that the method has high fault location accuracy,good noise robustness and strong adaptability.The fault location results are less affected by the fault distance and transition resistance.The thesis has 42 pictures,2 tables,and 61 references.