Distribution system reliability evaluation considering DG impacts

Under the force of environment issue and energy issue, distributed generation (DG) technique has achieved prodigious progress recently. Since normally distributed generators are installed near the customer side, so it will have a great impact on power system especially on distribution system. This paper discusses how distributed generations affect the reliability level of distribution system. A three-state model of DG is built. With given upstream and downstream island division of the load points, the probability of islanding is calculated. Based on short-term analysis, a method for the reliability evaluation in the distribution system which contains two or more distributed generators is proposed. Finally, the proposed method is used to analyze a sample system. On the one hand it demonstrates that the distributed generation has the ability of improving the reliability of system and customers. On the other hand it provides some useful conclusions such as the impact of the site of DG on reliability of distribution system.