一种改进的电网电压不平衡环境下链式STATCOM控制策略

An Improved Control Strategy for Cascaded STATCOM Under Supply Voltage Imbalance

电网电压不平衡现象在煤矿配电网中尤其严重,达不到国标要求。针对这种现象,提出一种改进的电网电压不平衡情况下链式STATCOM控制策略,一方面从全局、相间、相内三个层次,尤其是电网电压不平衡条件下控制直流侧电容电压平衡,另一方面通过正、负双序电流控制环对不平衡系统的无功和负序电流进行完全补偿。仿真分析与工业样机试验表明,所提出的链式STATCOM控制策略,不仅有效解决了不平衡环境下直流侧电容电压的平衡控制难题,并且提高了装置的抗不平衡能力。

Due to serious supply voltage unbalance in coalmine distribution network, an improved cascaded STATCOM control strategy under network voltage unbalance is proposed. In the proposed control strategy, on the one hand, under the supply voltage unbalance the balance of capacitor voltages at DC side is implemented by global control, clustered balancing control and individual balancing control, on the other hand, the reactive power and negative-sequence current of the unbalanced network are completely compensated by dual closed-loop control composed of outer voltage loop and inner current loop. Results of simulation and industrial prototype experiments show that the proposed cascaded STATCOM control strategy can effectively resolve the difficulty in the balance control of capacitor voltages at DC side under unbalanced network voltage, and the ability to resist imbalance of cascaded STATCOM is improved as well.