Distribution Network. Genetic Algorithm-based DG Recovery Strategy Study

The power users' requirement of power quality is constantly increased with the development of social, economic and people's quality of life. The security and reliability of distribution system which directly faces the user have impact on the users' demands, so it takes much concern and attention from the power sector. Since the service restoration of power distribution network is an important issue in system recovery, the formulation of distribution network fault recovery strategy becomes particularly important. The past personal experience can not be used in modern distribution system anymore, so the automation of distribution network is important. In recent years, the study of the distribution network fault service restoration strategy has made great progress and a variety of algorithms have been applied in reality as the development of communication and computer technology.The purpose of this paper is to improve the original algorithm of distribution network fault service restoration strategy, propose method of searching feasible solutions in maximize and enhance the efficiency of the algorithm. These are given as a reference for operator to keep switching operation and are helpful for improving operational efficiency, decreasing the time of failure removed or power supply recovery and improving the reliability of power supply.The paper discusses the strategy of fault service restoration for distribution network with DG by using genetic algorithm, the main contents and results of this paper are as following:(1) After the introduction of DG technologies, isolated islands operation mode exists in the distribution network. IEEE929-2000 agreement is not allowed isolated islands existence, as more and more access to distribution networks in the DG, many scholars have to consider the existence of isolated islands, then introduced isolated islands to reduce the areas of the electricity failure, and improve power supply reliability. Isolated islands of DG is the first step of recovery calculations on the distribution network. This paper applicates constraint satisfaction problem (CSP) model to solve the problem in the principle of an island divided when distribution network with DG confronts fault. Then introduced the process of isolating division, which achieve the continue electricity supply after fault happened, and establish the foundation for recovery strategies on the distribution network with DG.(2) Based on the division of the isolated islands, the characteristics of the genetic algorithm and genetic operation are studied. The problems about fault service restoration for distribution network such as genetic operators in the chromosome coding, population size, selection method, crossover operator, mutation operator convergence criteria and other aspects are in-depth understanding of the genetic operators in the chromosome coding, population size, selection method, crossover operator, mutation operator convergence criteria and other aspects of distribution network Recovery reconstruction problems(3) Minimum network loss and the least number of switching operations for the target model, the introduction of a distribution network for the forward and backward power flow calculation with the method, for example flow calculation, as an example to provide a basis into the genetic algorithm. Then used for the genetic algorithm will produce a large number of distribution network reconfiguration problem infeasible to make the following improvement strategies:the way the code for generating a more feasible solution, is the protection of a certain power requirements force some switches in the Closed state. A typical example used for the checking, the results of examples show that the proposed encoding genetic algorithm to improve efficiency in operations, can be effectively used for power distribution network fault recovery strategy.