Research On Three-phase Load Automatic Balancing Technology In Low Voltage Distribution Station Area

The low-voltage distribution network is advancing in the direction of intelligence and digitization,and the refined and transparent construction of the distribution station area is crucial.Due to the large number of asymmetrically distributed single-phase loads in the lowvoltage side three-phase four-wire system of the distribution network,the current three-phase imbalance in the distribution station area is still very serious,which increases the loss of the distribution network and affects the power supply quality also threatens the safety and stable operation of the power grid.For this reason,how to solve the three-phase imbalance problem on the distribution network side is a technical problem that needs to be solved urgently.Based on this,this paper has carried out the mathematical optimization modeling and algorithm research of three-phase load automatic commutation in the low-voltage distribution station area.However,the phase sequence optimization modeling is still inseparable from the support of the user phase sequence information,so it is also necessary to study the phase sequence identification method of users in the station area.First,the mechanism of the three-phase unbalance of the distribution network is analyzed,and the evaluation index system of the three-phase unbalance degree is established.However,the three-phase current imbalance evaluation index is diverse and lacks a criterion.Aiming at the question of how to choose one of the multiple evaluation indexes,a method for selecting the evaluation index of the three-phase current imbalance considering the line loss is proposed.The power flow calculation method is used to analyze the established three-phase unbalance evaluation index and the sensitivity of the change of the line loss rate,and finally a three-phase unbalance calculation index is determined.Secondly,the phase sequence optimization modeling based on the automatic balance of user load in the distribution station area needs to be supported by the user’s phase sequence information,and the phase sequence topology identification method of the low-voltage distribution station area based on multiple linear regression is proposed.Based on the correlation between the electrical energy collected by the customer’s meter and the distribution terminal,a regression equation based on the electrical relationship between the customer’s meter and the distribution terminal is established.From the perspective of regression analysis,the topological relationship of all power users in the district is determined.Finally,based on the preparation of the basic information in Chapters 2 and 3,a multiobjective optimization configuration is established that considers the smallest three-phase current imbalance,the smallest number of online automatic commutation switch adjustments,and the longest maintenance time of the phase sequence state after adjustment.The three-phase load automatic balance optimal commutation mathematical model in the station area,the nondominated sorting genetic algorithm(NSGA3)is used to solve the model,and the Pareto optimal solution is used as the commutation scheme of the model.In the calculation example,the traditional Considering the optimization results of the dual-objective model with the smallest three-phase current imbalance and the smallest number of online automatic commutation switch adjustments,the results show that the method proposed in this paper has more advantages.