A Novel Current Differential Protection Scheme for Active Distribution Networks

摘要

Conventiona1 distribution network is supplied from a single source. In such a network, both load current and short-circuit current flow in one direction. With the access of distributed generations (DGs), the fault characteristics of conventional distribution network are changed, further, traditional current protection principle faces with serious challenge. So, this paper presents a novel current differential protection scheme for active distribution networks (ADN). The protection scheme only utilizes the d-axis component of the current at both ends of the feeder, and internal fault can be distinguished from external fault by comparing differential current with restraining current. Meanwhile, the coefficient is introduced to ensure its reliability. This scheme can reflect all fault types and locate the faulty section within 10ms after the fault. Simulation results based on PSCAD show the validity of the proposed scheme.