Development And Research Of Three-phase Low Voltage Unbalance Compensation System

At present,various power electronic devices are widely used,the inconsistency and uncertainty of residential electricity consumption,and the existence of various non-linear loads,resulting in a large number of harmonic currents,three-phase load imbalance and Various power quality problems have led to an increasing focus on the improvement of power quality in low-voltage distribution systems.The three-phase unbalance compensation device based on active power filter(APF)not only can suppress harmonic current,but also compensates for three-phase load imbalance and reactive component,and achieves the purpose of comprehensive compensation,so it has received extensive attentionBased on a large number of literature reading summaries and theoretical analysis,this paper mainly expounds the causes of low-voltage three-phase unbalance and harmonic generation,and summarizes the development process and research status of three-phase unbalanced devices and harmonic suppression devices.The working principle and mathematical model of the unbalance compensation device of the threephase three-wire low-voltage active power filter are analyzed.In order to improve the power quality of the three-phase three-wire low-voltage power distribution system,this paper proposes a control strategy based on the synchronous reference coordinate system for the unbalance compensation,power factor and harmonic suppression of the low-voltage active power filter.Based on the theoretical analysis,the unbalance compensation simulation model of low-voltage three-phase three-wire active power filter based on MATLAB software is built.The simulation model realizes the unbalance of low-voltage active power filter under Park transform.Control strategies for compensation,improved power factor,and harmonic rejection;And participated in the development of a 70 KVA prototype,through the experimental test of the experimental prototype,to achieve the following functions:1.Compensating for the unbalanced current generated by the low-voltage three-phase load unbalance;2.Compensation for reactive power and improvement of power factor;3.Suppress harmonic currents.The experimentalprototype developed satisfies the requirements of the power quality standard for harmonic total distortion rate,three-phase unbalance and power factor,and achieves the expected effect.