A New Differential Protection Scheme of Distribution Network Line Based on Improved DTW Algorithm and 5G Communication

With the massive access of new energy, the differential protection will replace the traditional single-ended protection as the main protection of the distribution network line. Among the current differential protection channels, only 5G communication technology has both advantages of performance and price. However, using 5G communication as a communication channel needs to overcome the problems of delay jitter and data packet loss. This article first analyzes the principle of differential protection based on dynamic time warping (DTW) distance algorithm, and uses the nearest previous normal sampling point to replace the current abnormal one to deal with the problem of data packet loss, which is called alternative processing method. Secondly, the main starting criterion based on DTW distance of two-phase current and the auxiliary starting criterion based on DTW distance of the triple zero-sequence current are proposed. Thirdly, the calculation method of DTW algorithm under the short data window is proposed and the two operating criteria based on DTW algorithm are improved. And then, these 4 criteria are combined as a differential protection scheme for distribution network. Both theoretical calculation and simulation analysis show that the proposed scheme can operate well under different types of faults in different locations. With 5G communication delay being ignored, the scheme can operate in only 4–7 ms, and the data window of main operating criterion is only 3.75 ms.