The Research And Design Of Automatic Commutation Load Balancing Device In Low Voltage Distribution Network

Electric energy is an important energy source in the modern era.if the power quality problem is not solved properly,it will do harm to the power grid and even cause serious accidents.China’s low-voltage distribution network system is large and complex,and three-phase imbalance is a common phenomenon that has not been effectively treated for a long time.In recent years,the state and the power system have also issued a number of documents aimed at improving the power grid,so it is of great significance to study and manage the three-phase imbalance problem.The three-phase unbalance of low-voltage distribution network will cause many hazards,such as increasing line loss,heating or burning of transformers,disturbing computer systems and affecting residents’lives.Firstly,a three-phase load unbalance model is built in MATLAB,and the similarities and differences of grid parameters under balanced and unbalanced conditions are simulated,and the effects of three-phase load unbalance are summarized.Based on this,the four schemes of manual manual commutation,static synchronous compensator,power active filter and commutation switch are comprehensively compared,and the overall scheme of automatic phase change device based on load balancing is developed.Secondly,the hardware circuit of the main control box and the phase-change box of the load balancing device is designed,including ARM core board circuit,signal conditioning circuit,zero-crossing detection circuit and action circuit,etc.hen,in terms of software and data processing,the full-wave Fourier algorithm is programmed to calculate the three-phase voltage and current values and the data software is calibrated.The operation menu structure of main control switch box is designed to facilitate parameter setting and data monitoring.The variable frame length communication protocol is designed to ensure the stable transmission of data between the main control box and the phase change box.The commutation process under different loads is analyzed to give the switching process of continuous electrical commutation;When the multi-switch box network is running,two load switching strategies of unbalanced optimal commutation algorithm and genetic algorithm considering switching loss are given,and the example analysis is carried out.The results of numerical examples show that the proposed algorithm is effective.Finally,with the STM32F103 as the platform,the functional prototype of the automatic commutation load balancing device was developed,and the whole system was debugged and tested.The device can realize accurate measurement of three-phase voltage and current,communication function is normal,and the phase change box can Implement zero-crossing commutation and uninterrupted commutation of the load,this topic meets the design requirements.