基于“Ⅰ”型三电平中点钳位型逆变器的SPC不平衡补偿分析

Analysis of SPC imbalance compensation based on “Ⅰ” type three-level neutral-point clamped inverter

为治理低压配电网负荷的三相不平衡问题,研究了一种电能质量补偿装置,它由三相三电平中点钳位型逆变器组成。设计了具有复合结构的复数滤波器,其能够快速准确地提取电网电流的正负序分量。在分析逆变器原理和数学模型的基础上,推导出内嵌重复控制器的无差拍控制公式,以弥补输出电流和指令电流的延时,优化开关管开关机时的工作逻辑,保证"Ⅰ"型桥臂内、外管承受电压一致。基于MATLAB/Simulink仿真环境和物理实验平台对所提的结构和控制策略进行仿真和实验验证,仿真和实验结果表明,该装置能有效地补偿三相电流不平衡,提高电能质量。

Three-phase electricity demands are generally unbalanced in low-voltage distribution networks.To deal with this issue,a power quality compensation device composed of a three-phase three-level neutral-point clamped inverter is studied.A complex filter with composite structure is designed,which can extract the positive-and negative-sequence components of the grid current quickly and accurately.Based on the analysis of the principle and mathematical model of the inverter,the deadbeat control formula of the repetitive controller embedded is deduced to compensate for the delay of the output current and the instruction current.At the same time,the working logic of the switch tube during startup and shutdown is optimized.Consequently,that inner and outer tubes of the “I” type bridge arm bear the same voltage can be ensured.Finally,the proposed structure and control strategy are simulated and verified on MATLAB/Simulink simulation environment and the physical experiment platform.The simulative and experimental results indicate that the device can effectively compensate the three-phase current unbalance and improve the power quality.