Protective Relay Coordination And Optimization For Microgrid

With the energy crisis, environmental pollution and the contradiction of centralized power supply more and more prominent, the distributed generation technology developed rapidly because of its economy and environmental protection, at the same time, brought lots of problems. Microgrid technology has received more and more attention as an effective use form of distributed generation and the beneficial supplement of the utility grid. The protection issue is considered as the largest technical barrier for the further applications of microgrid technology. According to the fault characteristics of microgrid, the protection issue is studied in-depth and has been solved to a certain extent.Firstly, the characteristics of different types of distributed energy resources and its methods of grid-connected are discussed. The control methods of microgrid inverter are stated. Studying the common mathematical model, and then the simulink model of microgrid is established. Traditional protection scheme of distribution network is summarized; the influence of microgrid to protection system is analyzed in various fault conditions.Secondly, the application of ant colony optimization algorithm is introduced and the optimization model of protection coordination problems is built, to get the minimum total protection time, the coordination between relays is recovered by setting the starting values of relays. Distance protection is introduced into microgrid as backup protection of overcurrent protection, the coordination between two kinds of protection is realized by ant colony optimization algorithm.Finally, the protection principle of microgrid is proposed, the characteristic of the fault in microgrid is studied, and the bus, feeders and loads are equipped respectively according to the fault position.