Distribution Network Reconfiguration And Distributed Generation Optimal Allocation

As the distributed generation (DG) is connected to the distribution system, the structure and operation mode of distribution network will change. The power flow, losses and the voltage of the network will be affected, too. Through transforming the opening and closing state of its disconnected switches and tie switches, Distribution network reconfiguration alters the topological structures of distribution feeders, which contribute to reducing network losses and improving the voltage quality. Thus, it’s meaningful to study the optimal allocation of DGs by taking advantage of flexibility of topological structure of distribution network. The problems of distribution network reconfiguration, including static reconfiguration and dynamic reconfiguration, and optimal allocation of DGs are researched in this paper. The main works are shown below:(1) Concerning the inefficiency of pitch adjustment stategy of Harmony Search Algorithm, the pitch adjustment strategy based on heuristic rules are developped to avoid blind search of the algorithm. The simulation results of IEEE-33node system show that the convergence and optimizing efficiency are improved.(2)Concering the difficulty of determining the best time and the best structure for reconstruction, two step optimization of dynamic reconfiguration is proposed. The first step classifies the load data, thus the dynamic reconfiguration is converted to multiple static recongigurations, The improved Harmony Search Algorithm is used to solve each static reconfiguration problem. The second step introduces the benefit assessmet function, with a minimum income threshold to determine whether it’s necessary to change the topological structure according to the result of the first optimization result. The simulation results of IEEE-33node system show that the proposed method can effectively reduce switches operation times and achieve a good solution.(3) Concerning the intermittence and random functuation of load power and intermittent DGs’output, the bilevel optimal allocation model of DGs, considering dynamic reconfiguration is constructed in this paper. The upper level model optimizes DGs’allocation in distribution system. Based on the optimization result of the upper level model, the lower level model simulates the dynamic reconfiguration, optimizing switch states and dispatchable DGs’output. According to the characteristics of each optimization variable, Harmony Search Algorithm and the improved Harmony Search Algorithm are used for solutions. The simulation results of IEEE-33node system show that the proposed model improves the capacity to connect DGs. Despite increasing the cost of investment, operation and maintenance, raising the capacity of DGs can reduce power purchasing cost and exhaust gas treatment cost and improve system voltage quality.