分布式发电系统中并网逆变器的比例反馈积分控制技术

A proportion-feedback-integration control for the grid-connected inverter in distributed generation systems

分布式发电系统并网逆变单元输出电流的控制性能直接影响到系统输出的电能质量.传统PI控制无法消除并网电流(交流)的稳态误差,但稳态误差存在的根本原因相关文献描述较少.为了解释其原因,首先建立了并网电流线性控制模型,然后通过线性叠加定理和频域分析,揭示了传统PI控制交流量存在稳态误差的本质,并提出一种新的PI控制,即比例反馈积分PFI控制.PFI控制不仅解决了传统并网电流PI控制中存在稳态误差的问题,而且还具有直流抑制特性.此外,提出的PI控制具有原理简单,实现方便,单相三相系统均适用等优点.和理论分析一致,仿真结果验证了提出的PI控制的有效性.

Current control for the grid-connected inverter of distributed power generation systems has a significant impact on the power quality. The conventional PI control can not achieve the null steady-state error for the ac grid current, and the underlying reason for that is rarely depicted at length in literature. In this paper, the linear model for the grid current control is built, and then, the causes for the steady-state error in the conventional PI control is revealed based on the superposition theorem and frequency-domain analysis. A novel proportion-feedback-integration（PFI） control is proposed to eliminate the steady-state error and reject the dc component. It is easy to implement and applicable to both single-phase systems and three-phase systems. The simulation results are in agreement with the theoretical analysis, thus, verifying the effectiveness of the proposed approach.