Optimization Of Distribution Network Reconfiguration With Distributed Generation

With the increase in the number and capacity of distributed generation(DG)in the distribution network,the electrical characteristics of the operation of the distribution network have also undergone maj or changes.Distribution network reconstruction is one of the important means to optimize the operation of the distribution network.The essence is to change the operation status of the distribution network by adjusting the position of the tie switch and determine the best network operation structure.The reconfiguration of distribution network can effectively reduce network loss,improve power quality,and ensure the safe,reliable and economic operation of distribution network.The reconstruction of distribution network with DG generally only takes medium-voltage or high-voltage distribution network as the research object.Therefore,it is of great significance to study the optimization of two-voltage-level unified distribution network reconstruction with DG.In order to realize the reconstruction of the unified medium and high voltage distribution network with DG,this paper studies the distribution network with two actual voltage levels.The method is to reconstruct the high voltage and medium voltage distribution network respectively by iterative method on the basis of determining the operation mode of the substation.First,it analyzes the grid-connected interface types and equivalent node types of various DG,and gives an improved forward-backward power flow calculation method.In order to obtain the feasible solution of reconfiguration,the IEC-61970 connection model is used to map and simplify the distribution network,and the connection diagram and recomposition of the distribution network are determined.The minimum spanning tree algorithm is used to determine the structure of the distribution network that meets the radiative operation.In order to realize the unified distribution network reconstruction of high and medium voltage with DG,it is proposed that the operation mode of the main transformer in the substation should be determined firstly,and then the operation mode of the busbars on the power side and load side of the main transformer should be determined according to the heuristic rules,so as to determine the basic operation mode of the substation.The mathematical model of distribution network reconstruction is given.When solving the optimal reconstruction solution,the parameters and update strategy of particle swarm optimization algorithm are improved.At the same time,the random black hole strategy and perturbation mutation operation are adopted to improve the distribution and diversity of Pareto optimal solution.On the basis of the above work,a unified distribution network reconfiguration optimization algorithm with DG under two voltage levels is proposed.In Visual Studio 2013 platform,the proposed optimization algorithm program of distribution network reconfiguration is compiled with C++language.Taking the actual distribution network in a certain area as an example,by comparing various operating indicators before and after reconfiguration,it can be seen that the optimal solution of reconfiguration can effectively improve the operation state of the distribution network,and the feasibility and effectiveness of the proposed algorithm are verified.