Multi-terminal negative sequence directional pilot protection method for distributed photovoltaic and energy storage distribution network

Abstract

After high proportion of distributed photovoltaic and energy storage is connected to the distribution network by distributed multi-point T-connection, the traditional two-terminal directional pilot protection criterion will be affected by the output characteristics of distributed generation (DG) fault current, which leads to the wrong judgment of the fault direction. In response to the asymmetric fault of typical high proportion of DG T-connected to rural distribution network under the background that DG generally adopts negative sequence current suppression strategy, the paper studies the characteristics of negative sequence power direction when the measuring points of the main line and branch lines of DG distribution network in forward fault or backward fault under the negative sequence current suppression strategy, and puts forward a multi-terminal directional pilot protection method of distribution network with high proportion of DG based on negative sequence power direction, which solves the problem that the traditional two-terminal directional pilot protection in DG distribution network is not applicable. Finally, the correctness of the protection criterion is verified in Pscad/Emtdc.© 2017 Elsevier Inc. All rights reserved.