Procedures for fault location and isolation to solve protection selectivity problems in MV distribution networks with dispersed generation

Present planning and operation criteria used for MV passive radial distribution networks are, in general, not suitable to cope with the presence of a significant distributed generation (DG) capacity. In fact, many technical problems are still to be solved in order to increase DG penetration and to provide, at the same time, high service quality levels to customers.In this context, the present paper illustrates the results of the first part of a research project, conducted in collaboration with ENEL Distribuzione S.p.A. (Italy), which analyses possible solutions for various protection issues arising in distribution networks in presence of DG. The paper deals, in particular, with the problem of incorrect operation of traditional protection schemes for multi-phase and phase-to-ground faults in MV networks, and proposes a protection philosophy based on innovative technical solutions to solve the problem of lack of protective devices coordination in presence of DG to improve service continuity.