In this paper, the influence of the AC three-phase voltage unbalance problem in the low-voltage distribution network on the operating characteristics of the VSC is studied. This paper deduces the expression of the negative sequence component of the three-phase unbalanced voltage after park transformation and develops the simulation model of the lowvoltage DC distribution network. The correctness of the theoretical derivation is verified by simulation. The simulations of three-phase unbalances of 5%, 10%, and 15% were performed to investigate the effects of different three-phase unbalance on DC voltage. The results show that the three-phase voltage imbalance on the AC side will introduce a doublefrequency voltage component on the DC side. The greater the voltage imbalance, the larger the amplitude of the introduced double-frequency voltage component, and the more serious the impact on the DC voltage quality.

three-phase unbalance,double frequency voltage component,low-voltage distribution network,VSC