Low-Voltage Three-Phase Imbalance Filling Equipment Research And Design

The modern power electronic network and loads have present a new trend with the rapid development and application of the modern power electronic technologies.With a large number of non-linear, single-phase loads accessing such as electric arc furnaces and converter semiconductor devices, the three-phase unbalance, flicker, voltage fluctuation have been worse and worse. And it has become a seriously threatening to the safety of the electronic power network. So the research on how to optimizing the electronic power network is more and more important in the global wide especially the problems of three-phase unbalanced load balancing and reactive power compensation.For now the research of unbalanced three-phase system is only on the middle voltage distribution network of three-phase four-wire system but few on the low one.There is an solution on the combination of Δ-SVC and Y-SVC for this problem but the structures of this compensators conduced to big volume, high costs.So based on the problem above this paper provides a comprehensive compensation method which is used for active power balancing and reactive power compensation of unbalanced three-phase load in the low voltage three-phase four-wire distribution system by using power capacitors only, and also a method of grid voltage vector based on directional transformation used for detecting the active current and reactive current components of load fundamental current. The simulation results based on MATLAB/SIMULINK show the correctness and feasibility of this compensation method. Finally, using embedded ARM7LPC2138microcontroller and intelligent grouping of composite switch, we developed a low-voltage three-phase unbalanced compensation experimental prototype equipment and prepared a set of PC monitoring system, built the experimental system, carried out experimental study. Experimental results show that the compensator has excellent ability to balance the unbalanced three-phase load and to compensate for reactive power, as well as superior performance.