| With the rapid development of social economy and science and technology,people’s demand for power energy is increasing,the scale of distribution network is expanding,and the structure becomes more complex.At the same time,the deterioration of the ecological environment has limited the development and utilization of the original power generation energy,and a kind of environmental protection,convenient and economic distributed generation technology has emerged.With the development and application of distributed generation technology,the traditional distribution network has changed.The power flow of the network is not only one-way flow,but also the existence of loop network,which will make the network topology more complex.The traditional method of distribution network reconfiguration is to change the topological structure of distribution network by setting up the working state of most sectional switches and a few contact switches in distribution network,so as to optimize the operation of distribution system,such as improving line load balance,reducing system network loss,improving system power quality and reducing power supply cost.The traditional distribution network reconfiguration method is no longer applicable due to the access of distributed generation.Therefore,the importance of research on distribution network reconfiguration method with distributed generation is self-evident.Firstly,this paper studies the traditional methods of distribution network reconfiguration,mainly including the traditional mathematical optimization method and artificial intelligence method;the characteristics of distributed generation and the types of grid-connected nodes;distribution network topology analysis method and distribution network power flow calculation method with distributed generation.Then,an improved species birth and death optimization algorithm is proposed.The algorithm overcomes the shortcomings of the existing intelligent optimization algorithm,which is easy to premature and fall into local optimal solution.At the same time,the convergence speed is faster and the optimization performance is good.On the basis of studying the existing species birth and death algorithms,we found some problems,including that the original surviving species were not considered in the mass extinction operation,and the shrinkage coefficient was constant,which could not change with the iteration process.Then three improvements are proposed:firstly,adding original surviving species to the operation of species extinction can ensure the transmission of good species traits;secondly,random cross-mutation operation of derived new species can further increase species diversity;thirdly,the regularity of species birth and death algorithm is introduced.The convergence rate can be improved by changing the value shrinkage coefficient to the linear shrinkage coefficient which decreases with the iteration process.Finally,the improved species birth and death algorithm is applied to the optimal allocation of distributed generation and the reconfiguration of distribution network with distributed generation.Taking IEEE33 node and PG&E69 node system as examples,the simulation results are compared with those of particle swarm optimization and existing species birth and death algorithms.The experimental results verify the feasibility and validity of the proposed method. |
