Study Of Distribution System Restoration Strategy Considering Distributed Generation

As the economic development of all walks of life in society is affected by the power industry in the 21 st century,and the sharp decline in traditional energy and the policies of world’s green energy-related force humans to find new alternative energy sources,distributed power generation technologies such as wind power and solar power have been proposed.And with the rapid development of social economy,the access rate of Distributed Generation(DG)in the distribution system is increasing,which changes the distribution of the system power flow,leading to two important processes in the distribution network failure recovery strategy-the methods of fault location and restoration and reconstruction are no longer fully applicable.Since the power grid allowed island operation in 2003,the restoration strategy of the distribution network with distributed power sources has added an operation mode that has never been considered in the traditional distribution network-island operation.Therefore,through the study of fault location(FTU),restoration reconstruction and planned island division,this paper conducted a deeper research on the fault restoration strategy of distribution network with distributed power generation.This article introduced the current research status at home and abroad,and outlines the power flow calculation methods and distributed power flow calculation models that are repeatedly used in the fault recovery process of the fault recovery strategy-fault location,recovery reconstruction and planning islands which are the three processes involved in the fault recovery strategy.And the power restoration was divided into two parts:The first part is to consider the non-uniform power flow of the distribution network and the discrete problem of the switch information of the distribution network after the failure of the distribution network containing distributed power sources,and the switching function and objective function suitable for distribution network with distributed power generation was established.Then the improved binary particle swarm algorithm was adopted,and the algorithm was improved by considering the convergence of the algorithm and the local optimization problem at the same time.Taking the IEEE 33-node distribution network with distributed power supply as an example,the simulation analysis was carried out for different line faults,the number of distributed power connections,and the situation where the information uploaded by the feeder terminal(FTU)may be incorrect.It verified the effectiveness of the fault location method in this paper.The second part is to divide the distribution network restoration after fault location and isolation into reconstruction restoration and planned island restoration,and when the distribution network is not separated from the upper-level grid,priority is given to restoring the lost load through reconstruction.This paper selected the minimum loss of the distribution network as the objective function,and a "circle" processing of the complex distribution network was drawn,the Institute of Electrical and Electronics Engineering(IEEE)33-node system was used to carry out a calculation example analysis by improving the quantum particle swarm algorithm.The results show that the method in this paper can effectively reduce the network loss of the system on the basis of restoring all the power-loss loads,and at the same time can improve the overall voltage quality of the system.And when the distribution network is separated from the upper-level grid,the restoration of the power-loss load can be realized according to the island strategy.This paper also adopted the Floyd algorithm,priority was given to the load level,and divided the islands in the way of "search + adjustment",and selected the United States of America(US PG&E69)node for example analysis.By comparing with other algorithms,the results show that when the distribution network with distributed power sources is separated from the superior grid,the island strategy of this paper is used to restore the power-loss load,which can restore more important loads.