Research On Grounding Configuration Of TN-C System Based On Multi-Objective Optimization

In recent years,with China's increasing investment in the construction of distribution networks,the development of distribution networks has achieved remarkable results.However,due to the uneven development of the low-voltage distribution network in China's urban and rural areas,the safety and reliability of user electricity in some rural areas are lower than the urban distribution network,especially the low-voltage distribution network grounding system in urban and rural areas is not safe.In the grounding type of low-voltage distribution network in Fujian Province,the TN-C system has been respected by the power supply department because it does not need to install the general warranty and can save the investment of one line,but when using the TN-C system,it needs to be repeated Grounding measures.To this end,this article carries out the optimal configuration research on the grounding of the TN-C system from the multiple objectives of economy and safety.This article describes several configurations of low-voltage distribution networks and compares the characteristics of various configurations.Analyze the safety of TN-C system under different faults.Considering the economy and safety comprehensively,a method of repeatedly grounding the TN-C system neutral line is proposed.This method mainly establishes the multi-objective function and optimization model of the TN-C system grounding configuration,and then uses the optimization theory and optimization method for the TN-C system repeated grounding optimal configuration,and uses the penalty function method to deal with the constraint conditions in the optimal configuration,Linear weighting method is used to convert the multi-objective problem in the optimization configuration into a single-objective problem,and after analyzing several common optimization algorithms,the specific algorithm flow for solving the optimization model is given.Finally,set a set of example parameters of the TN-C grounding system of the low-voltage distribution network,and bring the set example parameters into the optimization program for simulation,and obtain the graphs of the number of repeated grounding changes with the number of iterations,and the contact voltage.The graph of the change of the number of iterations and the graph of the change of the zerosequence current with the number of iterations.According to the obtained graph,the optimal number of repeated grounding of the TN-C system in the case of single-phase short-circuit grounding and two-phase short-circuit grounding occurs,thus,the optimal number of repeated grounding times that can satisfy the three constraints of the lowest repeated grounding cost,the lowest contact voltage and the maximum zero-sequence current is obtained.The results show that the method proposed in this paper is feasible and effective.