Abstract:

Under the condition that the load of the grid is too large and the unbalance is high,the three-phase four-wire unbalance regulator had the phenomenon that the active compensation current exceeds the rated capacity of the equipment.The common method to solve this problem is to limit the amplitude,but this method can distort the active compensation current waveform and cause voltage fluctuations on the DC side of the equipment because the sum of the three-phase active currents flowing into the equipment is not zero.This paper introduces the working principle of the three-phase four-wire unbalance regulator,and analyzes the shortcomings of the limiting method,and finally proposes a new active current compensation scheme,i.e.,the active compensation current proportional reduction method.The correctness of this method is proved by mathematical derivation.Finally,it is verified through simulation and experiment that this method can avoid the drawbacks of the limiting method and maximize the regulating effect of the device.

Key words: three-phase four-wire unbalance regulator, active compensation current, limit amplitude