Optimization Of Contact Structure For Middle Voltage Distribution System Based On Total Supply Capacity

National Energy Administration issued the "distribution network construction transformation action plan(2015-2020)" proposed to optimize the structure and eliminate the weak links as a key task,to carry out distribution network grid optimization action,to strengthen the medium voltage distribution site,to establish a strong load transfer channel,to enhance the flexibility and reliability of power supply,to improve the power supply and security level of urban areas.At the same time,because the distribution network is usually used "closed-loop design,open-loop operation",and the tie-line which is the important channel of load transfer as an important part of the closed loop,plays a key role in improving power supply reliability,power supply capacity and the utilization of equipment.So the planning results of contact structure directly affect the operation of the entire distribution network safety and economy.In this paper,we establish a planing model of contact structure among main transformer station based on pareto optimal.Firstly,considering the N-1 safety criterion and the actual operating conditions,the influence of the overload factor and the secondary power supply process on the total supply capability(TSC)of the distribution network is analyzed.Based on the TSC model of feeder interconnection,the linear programming method is used to solve the model.Meanwhile,the optimal load distribution of the distribution network is obtained by using the feeder load balancing model.Secondly,in order to balance the effectiveness and economy of the contact structure planning results,a multi-objective planning model of the contact structure considering the TSC and the minimum contact cost which takes the influence of geographical factors is established.Using the NSGA-? algorithm to solve the model and taking the obtained pareto individuals as alternative options.The variation coefficient method and the TOPSIS method are carried out to sort alternative options to select the best contact structure optimization.The resulting optimization not only contains the contact corridors between the main transformers,but also shows the composition of the number and location of contact branches clearly.Finally,the validity and effectiveness of the proposed method is verified by the analysis of a practical example.