用于电能质量治理的三电平变流器预测无差拍重复控制优化及性能分析

Optimization and performance analysis of predictive deadbeat repetitive control of three-level converter for power quality improvement

针对用于低压配电网负荷谐波、三相不平衡和无功补偿的三相四线制T型三电平变流器,对其控制算法进行了整体优化。首先,根据dq0坐标变换前后不同频率分量之间的映射关系,设计了快速指令电流提取与预测算法,该算法不仅能够独立提取谐波、不平衡和无功分量,而且指令电流提取时间缩短至10 ms;其次,针对无差拍控制延时问题,设计了即时采样与预测无差拍重复控制结合的控制器进行优化,并分析了所提控制器的性能;最后,搭建了13 kV·A的物理样机,测试结果证实了相较于传统的预测无差拍重复控制,所设计的控制策略具有更好的控制精度与稳定裕度。

Aiming at the three-phase four-wire T-type three-level converter applied to compensate load har⁃monics,three-phase unbalance and reactive power of low-voltage distribution network,the control algorithm is optimized overall.Firstly,according to the mapping relationship between different frequency components before and after dq0 coordinate transformation,a fast instruction current extraction and predictive algorithm is designed.The algorithm can not only extract harmonics,unbalance and reactive components independently,but also shorten the instruction current extraction time to 10 ms.Secondly,the controller with combination of real-time sampling and predictive deadbeat repetitive control is designed to optimize the problem of deadbeat control delay,and the performance of the proposed controller is analyzed.Finally,a 13 kV·A physical prototype is built,and the test results confirm that the designed control strategy has better control pre⁃cision and stability margin than the traditional predictive deadbeat control.