重复控制三相电压型准Z源光伏并网逆变系统

Three-Phase Voltage-Fed Quasi-Z-Source Photovoltaic Grid-Connected Inverter System With Repetitive Control

为提高准Z源逆变器的升压能力和并网电流质量,提出了一种采用重复控制的强升压能力的单级三相电压型准Z源光伏并网逆变系统,并对这种逆变系统的电路拓扑、改进的空间矢量脉宽调制(space vector pulse width modulation,SVPWM)控制策略、离散控制系统的稳定性和调制器设计进行了分析。该系统电路拓扑是由大升压比准Z源阻抗网络、三相逆变桥和三相LCL滤波器构成;改进的SVPWM控制策略包括光伏阵列最大功率点跟踪控制和储能电容电压外环、并网电流内环控制,其中并网电流内环采用逆变器侧电流反馈控制策略,且融入了电网电压比例前馈、重复控制和PI串联的嵌入式复合控制来提高并网电流质量。实验结果证实了所提逆变系统电路拓扑、控制策略和系统设计的有效性。

In order to improve boost capability of quasi-Z-source inverter and grid-connected current quality, a single-stage three-phase voltage-fed quasi-Z-source photovoltaic grid-connected inverter system with strong boost capability with repetitive control is proposed. Circuit topology, control strategy of modified space vector pulse width modulation （SVPWM）, system stability and modulator design under discrete control system were researched. The circuit topology is composed of a high boost ratio quasi-Z-source impedance network, a three-phase inverter bridge and a three-phase LCL filter. The modified SVPWM control strategy includes control for maximum power point tracking （MPPT） of photovoltaic array and outer loop control for energy storage capacitor voltage with inner loop control for grid-connected current. Inverter-side current feedback control strategy is used in grid-connected current inner loop with grid voltage proportional feedforward, repetitive control and PI series embedded composite control to improve grid-connected current quality. Experiment results show validity of the inverter system topology, control strategy and system design.