Protection Scheme for Flexible DC Distribution Lines Based on GRU Network

For the problems of the difficulty in setting the thresholds, the operation failures caused by high impedance faults and the insensitivity under noise interference in the protection of the flexible DC distribution lines, a protection scheme for the flexible DC distribution lines based on the GRU deep learning model is proposed in this paper. Firstly, the amplitude-frequency characteristics of the short circuit faults based on the current-limiting reactors are analyzed, and the fault characteristic quantities under the frequency domain features are extracted through the generalized S-transform, which are taken as the input data of the gate recurrent unit (GRU) network. Then, the GRU deep learning model is constructed and trained to extract the deep features of the fault samples under time series. Combined with the support vector machine (SVM) classifier, the fast fault identification and isolation are realized. Finally, the simulation model is built in the PSCAD/EMTDC to verify the feasibility of the protection scheme. The simulation results show that the scheme has strong anti-interference ability and high sensitivity, which meets the requirements of the reliability and quickness in DC line protection. © 2021, Power System Technology Press. All right reserved.