Research On Three-phase Unbalance Regulating Method Of Low-voltage Distribution System Based On Passive Compensation Network

With the continuous development of the social economy,the application of sensitive loads is increasingly extensive,so higher requirements are placed on the power quality.Three-phase unbalance is an important index of the power quality of power systems,especially for low-voltage power distribution systems,and has become a common concern for power supply enterprise and users in recent years.Although many theoretical researches and field application practices have been carried out for this issue at home and abroad,the overall effect is poor and needs further study.This paper builds a passive compensation network based on inductance and capacitance elements,and studies the three-phase unbalanced optimization regulation strategy and implementation of low-voltage power distribution system.Firstly,the basic principle of unbalanced current compensation in distribution network is analyzed.Inductive or capacitive components crossover between phases and relative grounds,the effective control of three-phase unbalance is realized by transferring reactive current and active current.Based on Steinmetz-theory,a three-phase unbalanced passive compensation network model,suitable for three-phase four-wire low-voltage distribution network,is constructed.The unbalanced current can be effectively adjusted by combining a Y-compensator and a D-compensator.Secondly,under different optimization objectives,the passive compensation network parameter adjustment strategy is studied.Focusing on the aims of improving power factor and minimum network loss,optimization of inductance and capacitance in passive compensation networks is proposed for eliminating negative-sequence and zero-sequence current components.Thirdly,based on the working principle of the TCR+FC type Static Var Compensator,a realization method of three-phase unbalanced compensation network based on TCR+FC is studied.Finally,based on PSCAD simulation software,considering distribution systems with distributed power supply,the three-phase four-wire distribution network simulation model is established.Comparing with the simulation of unbalanced control method based on intelligent commutation switch,the effectiveness of the control is compared to verify the effectiveness and superiority of the three-phase unbalanced passive compensation network.The research conclusions of this paper not only enrich the research results in the related fields of three-phase unbalanced control measures of low-voltage power distribution systems,but also provide theoretical support and technology for solving the voltage quality control of intelligent low-voltage distribution networks that are highly infiltrated by single-phase distributed power supplies.