State estimation protection method of metal return bipolar DC distribution line with immune abnormal data
The measurements in the actual engineering may be interfered by abnormal data,which increases the risk of protection malfunction.For this reason,based on the idea of model matching,a DC distribution line state estimation protection method immune to abnormal data is proposed.Considering the inter-pole coupling of metal return bipolar DC lines,a refined equivalent model of the line is established.Accordingly,the measurement equations of the system are obtained and discretized according to the quadratic integral method to facilitate the solution.For the problem of possible abnormal data,it is proposed to preprocess the data based on the window graph Fourier transform,which treats the data as graph signals and gives the concept of"frequency",and extracts the low-frequency signals to achieve the purpose of eliminating the high-frequency abnormal data,such as random pulses.The preprocessed line state estimation model is solved based on the recursive least square algorithm,and the protection criterion is constructed according to the matching degree between the estimation model and the measured model,to realize the identification of in-area and out-of-area faults.Simulative results show that the method can quickly and accurately recog-nize in-zone faults and effectively avoid abnormal data interference,and has well performance of high resis-tance and communication delay resistance.
DC distributionline protectionabnormal datagraph Fourier transformstate estimationrecursive least square
万方数据
维普
