Penetration level optimization for DG considering reliable action of relay protection device constrains

Great changes will happen to the distribution network structure with the distributed generation(DG) connected into the network, and the power flow and short-circuit current in distribution network will also change correspondingly. All of these have effects on the normal operation of relay protection device in distribution network. The more DGs are connected into the network, the greater influence on the operation of relay protection device. In order to guarantee reliable action of the original relay protection device in distribution network, it´s necessary to study on the maximum penetration level of DG. In this paper, the effects of DG on distribution network current protection is analyzed. A calculation model of distribution network with DGs is built taking into account reliable action of relay protection device constraints, and a calculation method based on niche genetic algorithm is proposed which is explained by example of a 34 nodes multiple DGs system.