基于CPT理论和重复控制的多功能并网逆变器研究

Research on Multi-Functional Grid-Connected Inverters Based on Conservative Power Theory and Repetitive Control

针对具有电能质量治理和功率输出功能的三相三线制多功能并网逆变器,提出在两相静止坐标系下基于CPT功率理论的改进电能质量补偿分量计算方法,实现在并网点电压畸变情况下不引入锁相环,提取负荷电流中的谐波、无功和不平衡分量。为实现对负荷电流补偿分量跟踪输出以及在畸变电压干扰下的输出电流控制,同时简化电流内环控制器结构,采用H∞重复控制理论设计逆变器输出电流控制环。由于多功能并网逆变器在运行中,控制环节稳定性受到本地负荷以及并网点线路阻抗的影响,基于由CPT理论构建的一般负荷模型,提出适用于复杂负荷以及线路阻抗接入情况下的H∞重复控制系统稳定性分析方法。最后在硬件实验平台上对所提出多功能并网逆变器控制策略进行了验证,实验结果表明其有较好的电能质量治理能力。

For the three-phase three-wire multi-functional grid-connected inverters,a modified power quality compensation strategy was proposed in the paper based on conservative power theory(CPT)in two-phase stationary coordinate system.The proposed strategy can extract the compensation components of the load currents without the phase-locked loop(PLL),even when the voltages of the point of common coupling(PCC)are distorted.Then,the output-current control loop was designed based on H∞repetitive theory to realize the load current compensation as well as the active power output control under distorted voltages.By considering the local load,the general load mode according to CPT was adopted.Thus,a stability analysis method was proposed to study the stability problem of the current control system with the H∞repetitive controller,which is suitable for complex loads and grid-impedance scenarios.Finally,the proposed control system was tested in a hardware platform.The experimental results show that the proposed strategy can compensate the power quality problem.