Study Of Medium And High Voltage Distribution Networks Reliability Evaluation Methods

With the development of urban economy and the improvement in life quality of the people,the requirement to the electric energy quality of user has been more and more rigorous.The distribution system has a direct connection to customers,so distribution system can make most influence on customers.The statistics show that more than 80% letting off of customers is leaded by distribution system fault.Thus,the reliability of distribution system plays an increasingly important part in power production and management.So the evaluation of distribution system reliability and improving system reliability is most significant.Based on the introduction to the significance of the study on the distribution system reliability and domestic-oversees analysis on it, this paper goes to the details of relevant concepts and main aspects of distribution system reliability study, mainly including every index and calculation formulate,the reliability model and its calculation formula of the components in the networks.Then analysis the available methods of reliability evaluation ,conclude their advantages, disadvantages and applied objects.The principles of choosing the method of distribution system reliability evaluation are exponded ,which is helpful to pick the method in terms of concrete distribution networks reliability evaluation.Taking all kinds of influencing factors into consideration, this paper proposes a method of reliability evaluation which is an integration of the net equivalence method and graph theory method. First of all, make a sense of the picture's saving way, after that, the method of using the adjacent matrix to save net information is determined. Secondly, make use of net equivalence method to simplify the complicated distribution networks, of which the processes can be divided into upwards and downwards equivalent methods, viz. make the complicated radial net be upwards equivalent with the simple net to accomplish the calculation, after that, calculate its impact on next net layer in downwards equivalent method. Thirdly, make use of MATLAB to achieve the arithmetic on complicated distribution networks reliability evaluation.Finally, take the test of the main feedback line F4 which is based on IEEE and RBTS Bus for example, compare this test result with other test results coming from other methods ,which demonstrates that this method is effective.