Research On Distribution Network Reconfiguration Based On Harmony Search Algorithm

The structure of distribution network is complex,and its operation mode is more flexible.In order to optimize the operation of distribution network,it is necessary to change the network structure under the premise of meeting the operation constraints of distribution network,which is called distribution network reconfiguration.The advantages of reconfiguration are reducing network losses,obtaining better voltage quality,and making load distribution more balanced,etc.In addition,reconfiguration is the preferred method to optimize the distribution network operation without additional investment.Distribution network reconfiguration can be regarded as a mathematical optimization problem.When the network structure is sophisticated,there are some problems in solving process,such as low solving speed and too many infeasible solutions.In order to solve above problems,the main work of this thesis is as follows:(1)Based on the concept of "branch group" in distribution network,the meaning of reconfiguration solution is explained,then "branch group solution" and "concrete solution" are defined.The general situation of infeasible solutions is analyzed,and how to avoid the generation of infeasible solutions in the process of forming solutions is proposed.(2)The application value of branch group solution is analyzed by mathematical method.The results show that the branch group solution is close to the optimal solution,in the current open-loop state.It is reasonable and feasible to use the branch group solution to represent a network open-loop state.This part provides a theoretical basis for the fast network reconfiguration method proposed in this paper.(3)Harmony search algorithm is applied to distribution network reconfiguration and detailed scheme flow is given.The reconfiguration methods based on harmony search algorithm are divided into two kinds.The first one is optimizing the branch group solution separately.After obtaining the optimization result,the branch group solution is optimized again and the concrete solution is obtained.The second one is optimizing branch group solution after its formation,and then forming the corresponding concrete solution one by one,and finally getting the best solution of network reconfiguration.Researches show that both methods can achieve the expected effect of distribution network reconfiguration.The reconstructed network loss is much smaller than the original network loss of the distribution network.The second method is slightly better than the first one,but it takes longer time.The first method has a shorter operation time while guaranteeing the reconfiguration effect at the same time.(4)The application scenarios of distribution network reconfiguration are analyzed by using scheme.The network loss optimization under normal condition and fault recovery under fault condition are selected for analysis.The results show that the proposed scheme has the advantages of reconfiguration effect and speed.