The Research On The Distribution Network Reconfiguration Strategy Based On Group Search Algorithm

Distribution network reconfiguration is one of the effective ways to improve the reliability of power supply and reduce the cost of network operation. The essence of distribution network reconfiguration is to make the whole network run under a certain optimal index by changing the network operation structure. When the load fluctuates, by changing the state of opening and closing of the switches in the network to change network operation structure, so as to reduce the line loss, load balancing and improve the voltage quality and so on. According to the fluctuation of load in time period, the reconfiguration of distribution network can be divided into two categories: static reconfiguration and dynamic reconfiguration. The static reconstruction is commonly used in the distribution network planning and designing to solve a time point or constant load case of the network structure optimization problem; the dynamic reconfiguration can solve the problem of network structure optimization during the entire running time period of load fluctu ation. Because the dynamic reconfiguration can satisfy the operation demand of the reality of the grid, this thesis comprehensively analyzes the differences and relations between the two types of reconstruction, the research focuses on the dynamic reconstruction based on the static reconfiguration.Network topology analysis and power flow calculation is the basis for reconfiguration of distribution network, this thesis combined with the structural characteristics of the distribution network select the node branch matrix of graph theory that describes topological structure of distribution network and forward and backward substitution method to calculate the distribution network power flow. On this basis, due to group search optimization algorithm have not only simple principle, flexible search mode and extremely high computational efficiency, but also able to avoid falling into local optimal solution and obtai n the global optimal solution with greater probability, so this thesis choice group search algorithm for solving the static reconfiguration problems. According to the simulation results of the standard examples of distribution network, the results show that the group search algorithm can greatly reduce the network loss and improve the voltage quality.Based on the static reconstruction, through the analysis of the dynamic characteristics of the distribution network,this thesis concludes the key problems of dynamic reconfiguration: how to deal with the dynamic reconfiguration interval division in running time and how to deal with multiple switch constraint. This thesis conduct dynamic reconfiguration by using the sub-period optimization strategy and structuring the objective function including switching operation cost and the stepped price. The sub-period optimization strategy is used to divide reconstruction interval in dynamic reconstruction. Additionally, the objective function is used to solve the problem of multiple switch constraint processing in dynamic reconfiguration. According to the simulation results of the standard examples of distribution network, the results show that the proposed method can meet the constraints of distribution network operation and obtain the dynamic reconfiguration scheme of the lowest operating cost.