A Differential Protection Scheme for Distribution Networks with Multiple T-connected Inverter-Interfaced Distributed Generators

Inverter-interfaced distributed generators (IIDGs) connected to distribution networks may cause the failure of conventional three-stage current protection or current differential protection. In this paper a novel differential scheme for distribution networks with multiple T-connected IIDGs is proposed. After building and analyzing the positive-sequence equivalent circuit of distribution networks with multiple T-connected IIDGs and equating multiple IIDGs to single IIDG, the protection criterion of this scheme is constructed only according to electrical quantities at both ends of the protected line. A simulation in MATLAB of a distribution network with multiple T-connected IIDGs is built to validate this proposed protection scheme. The feasibility and reliability of the proposed protection scheme are proved by the results of case studies.