基于外环功率控制的并网逆变器研究

Research on the Grid-connected Inverter Based on Outer-loop Power Control

针对前级输出恒定直流电压的光伏或风电系统,研究适用于该系统的并网逆变器控制策略,采用功率外环电流内环的双环控制结构,由系统的最大功率点追踪(MPPT)算法综合系统运行状态给出功率外环的给定值,与并网逆变器实际输出功率比较,经功率外环调节器输出有功电流给定值,再由电流内环调制控制,最终实现并网逆变器在不同功率因数下的稳定运行。在风电模拟运行平台上,对额定30 kW并网逆变器进行了实验研究,结果验证了该并网逆变器控制策略的正确性和有效性。

Aimming at photovoltaic system or wind power system outputting constant DC voltage, research on the control strategy of the grid-connected inverter suitable for this system is put forward.A novel dual-loop control structure that consists of power outer-loop and current inner-loop is adopted in the inverter.The reference value of the outer-loop is provided by maximum power point tracking（MPPT） and integrative system operation status.After compared with the actual output power,the active current component is given by the power outer-loop regulator.The stable operation under different power factor of the grid-connected inverter is realized by the current inner-loop regulator.The prototype of 30 kW rated grid-connected inverter is tested on developed wind simulation operation platform in the laboratory. The experimental results verify the correctness and effectiveness of the control structure and strategy of the grid-connected inverter.