Reliability Evaluation for Complex Distribution System Based on the Simplified Zone Model and the Minimal Path

A method of reliability evaluation for complex medium-voltage distribution system based on feeder partition model and the minimal path method is proposed in this paper. According to the topology of distribution system, a distribution network is divided into different zones, and then the distribution network is changed into an oriented diagram. Applying the minimal path method, this diagram is divided into the minimal path and the sub- systems, based on network-reliability equivalent. The effect of failure of the components in the sub-systems on the load point is converted into the corresponding node connected with the sub-system in the minimal path, so the reliability indices of the load point can be calculated according to the load point's minimal path by use of the consequence analysis of fault Pattern. By enumerating all the load points and applying above technique, the reliability indices of the electrical distribution system can be calculated. The application of the proposed algorithm to RBTS-Bus6 shows its effectiveness. The method for the reliability evaluation of a distribution system is divided into two classes: the simulation method and the analytical method (1, 2). Based on the random experiments, the calculation structure of Monte Carlo simulation method is very simple, but the error is in inverse proportion to the times of experiments, to reduce the error need longer calculation time. Based on Markov model, the accuracy of the analysis method is very high, the basic method is failure-mode-and- effect analysis technique (FMEA), but the calculation quantity increases in exponential with the number of components, when the number of components is significant, it will be very difficult to calculate the reliability. At present, to reduce the reliability evaluation efficiency of distribution system, there are some methods such as minimal path method (3), reliability network equivalent method (4, 5), Reference (6, 7, 8) presents an effective approach based on zones, zones are created by encircling all the components between protection device and switches in a feeder, and it is obvious to reducing the number of components of evaluation of reliability of distribution system. Comparing with the direct FMEA, these methods can improve the calculation efficiency in certain degree. Based on the minimal path , the feeders partition and network equivalent , a new approach for the reliability evaluation of the electrical distribution system is presented in this paper.