Research On Distribution System Reliability Containing Distributed Generation

With the intensification of the world’s energy crisis and environmental issues, the development of distributed power technology has been valued by countries and power supply companies. As the same time, reliability of distribution system has gradually become a research hotspot. It not only relates to the user’s life, but also affects the economic efficiency of power supply enterprises. When distributed generation connects to the distribution system, the construction and operation mode of traditional distribution system are changed. So accurately evaluating the reliability of the distribution system can provide theoretical support for the planning, construction and operation of the distribution system, and promote the development of new energy sources.The main content and the research results of this paper are as follow:(1) The characteristics and types are studied, the influences on distribution system after accessing the distributed generation are summarized. It laid the theoretical foundation for the research on distribution system reliability containing distributed generation.(2) The assessment methods and procedures of distribution system are analyzed, using the M-file of Matlab for analytical method and Monte Carlo method programming respectively and taking IEEE RBTS Bus6as an example. The results show that using the Monte Carlo method is better distribution system reliability evaluation. Because it considers the randomness of the distributed generation’s output power.(3) Considering the randomness and intermittence of wind and solar energy, the simplify methods and multi-state models of wind turbines and photovoltaic generation system are presented. The wind speed time series models and output models of wind turbines are established, using moving average model to get the wind speed. The illumination intensity time series models and output models of photovoltaic generation system are established, using HOMER to get the illumination intensity. The reliability of the evaluation model of energy storage devices and time-varying load models are also established. Finally the accuracy and effectiveness of models are validated.(4) According to the form and operation mode of distributed generation accessing to distribution system, the reliability of distribution system is analyzed. When system failure occurs, the classification of the island, classification principles and models, methods of solving the model is researched. Due to the types, capacity and location of distributed generation, the reliability of the distribution system is evaluated. The following conclusions are obtained: accessing distributed generation to distribution system can improve the reliability of the load point of the island and the whole system; after adding energy storage devices to distribution system, reliability of load points and system is higher; with the increase of DG capacity, reliability of load points and system will be raised; and DG closer to the access point, the better reliability of the load point; when DG accessing sporadically to distributed system in the end of feeder, the reliability of system can be improved.