Distribution System Reliability Evaluation Considering The Impacts Of Distributed Generation

Under the force of environment issue and energy issue, DG has achieved prodigious progress recently. And it is deemed to be the future development of modern power system. But normally distributed generators are installed near the customer side, so it will have a great of impacts on power system especially on distribution system. This paper mainly deals with the reliability evaluation of a distribution system which has one or more distributed generators installed in it. And the main tasks are as follows:Firstly, it reviewed the methods which are widely used in the reliability evaluation of conventional distribution systems. The comparisons among the different reliability models of electrical components and the whole system are made.Secondly, it introduces the impacts of distributed generation on distribution system, especially on the reliability aspect, and analyzes how distributed generation affect the reliability level of distribution system. Because of the fluctuation of the distributed generator's output, and the output may not satisfy the load demand in an island during some time period, here using a 3-state-model which contains sub-rating state and short-term analysis to cope with these problems. Then using the concepts of minimal island and islanding probability, we achieved the reliability evaluation of the distribution system containing one distributed generator.Based on these, we propose a method for the reliability evaluation in the distribution system which contains two or more distributed generators, and deduce many expressions which suit different sections of the distribution systemFinally, we use the proposed method 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 conclusions which may be very useful for the future distribution systems planning.