三相并网逆变器的双环控制策略研究

Research on Two Loop Control Strategy in Three-Phase Grid-Connected Inverter

由于对高频谐波的抑制效果明显好于L型滤波器,因此LCL滤波器在电流源控制的并网逆变器中应用越来越广泛。而针对该类型的并网逆变器的控制策略更为复杂,为了简化控制策略一种基于电流双环的并网控制方案被提出来。与电压电流的双环控制器设计方法不同,设计电流双环控制器参数时除了考虑内外环控制器的相互影响以外,还需要考虑双环控制器带来的降阶和少自由度问题。因此本文在介绍基于高阶极点配置的电流双环控制器设计方法的基础上,重点分析在电流双环控制带来的少自由度的情况下如何合理的设计控制器参数。实验结果表明,根据该方案设计的控制器参数能够使三相并网逆变器安全、可靠运行且具有较快的动态响应速度。

Because LCL filter has better performance in harmonic suppression comparing with L filter in the same inductance values, it is gradually used in currant-control gridconnected inverters. In order to simplify the control strategy, a two-loop current control strategy is adopted. Different from two-loop controller with voltage outer loop and current inner loop, the two-loop current controller parameters must consider the impact on each other, but also need to consider reducing order and limited degree of freedom. This paper focused on analyzing how to design the two-loop current controller parameters reasonable under limited degree of freedom condition. Based on the proposed design method, the controller can ensure the stability and dynamic performance of the grid-connected system. And this is verified by the experimental results.