A Power Differential Protection Scheme for Distribution Network with High Penetration of Distributed Generation

Distribution network changes from single-source network to multi-source network with bi-directional power flow due to connection with a large quantity of distributed generation (DG). Traditional three-stage over-current protection for the network may maloperate or fail to operate. In this paper, a power differential protection scheme is proposed, which consists of a main criterion and an auxiliary criterion. The main criterion is constructed based on the energy conservation law. Differential power of line terminals is used to discriminate internal faults from other conditions. Furthermore, an auxiliary criterion is constructed to deal with the false action problem caused by voltage drop of the bus. Although two-point information of the distribution line is used, the scheme has low synchronization requirements. Simulation results by PSCAD/EMTDC verify the effectiveness of the proposed scheme under various conditions for distribution network with high penetration of DG.