Adaptive overcurrent protection to mitigate high penetration of distributed generation in weak distribution systems

The Growth in penetration Distributed Generation (DG) in the Distribution Network consequently rise and become widespread practise due to the increasing demand for electric supply. Integration of DG units in the Distribution Network lead into a significant change in the characteristic and configuration of the distribution network in many aspects, and could be characterized in terms of stability and reliability, which caused by the disturbance in the protection system configuration such as distance protection over and under-reach and over-current mis-coordination, especially in high penetration conditions. This paper presents a case study for integration a relatively large amount of distributed generation (DG) into a weak medium voltage distribution network (DN), addressing the problems resulted from integrating DG units into the distribution network, in particular, the planning and operation of distribution network protection with significant penetration of DG units. The adaptive method approach presented in this paper overcome the mis-coordination problems comes from connecting DG units to a typical distribution grid based on activating the directional functions and adding multiple group settings which a feature exist in all modern numerical protective relays. The theoretical analysis will be validated using simplified power system representing the Eastern Libyan Network simulated in NEPLAN package. Simulation and results indicate that the proposed adaptive protection scheme is a viable method to effectively mitigate the impact of DG penetration on protective devices, in addition enhancing the reliability and selectivity of the protection system.