Research On Reliability Evaluation Of Medium Voltage Distribution Networks

At present,along with growing demand need of power energy,the power supplying quality of distribution system are of main significance to the users.This paper explores the load transfer and evaluates the reliability of the network based on the research of structure of distribution which provides the reference to the decision on electric power department.Main results are as follows:The topology of the distribution is investigated,the mathematical description of the topology is realized by the adjacency table.Both static global topology and dynamic local topology are used to reduce searching range and speed up network modeling.Based on this,the topology technology of load transfer is putting forward,and the network is simplified by shrinkage of the distribution network.This thesis puts forward a better load transfer strategy based on a systematic research.Aiming at the effect of load change,a load transfer model is built which is calculated by an improved heuristic search algorithm.This algorithm can find the solution by combining the tree cutting and heuristic algorithm.And the optima load transfer method is obtained by focusing on five aspects including of voltage quality,line capacity margin,switching operation frequency,load equalization rate and impulse current.This thesis puts forward a reliability algorithm for distribution network using the Bayesian network.A four-layer Bayesian network of distribution network consists of the component layer,the section layers,the load point layer and the system layer.By enumerating the failure of the block and the switching element,the node type of the load point is obtained and the reliability is calculated.The weaknesses for the network are identified according to Bayesian network reverse reasoning.Through the example of IEEE 69 node and RBTS-BUS2 distribution system,the correctness and feasibility of the algorithm is verified.