线性自抗扰技术在LCL逆变器并网电流控制及有源阻尼中的应用

Application of Linear Active Disturbance Rejection Technique in Grid-Connected Current Control and Active Damping of LCL Type Inverter

有源阻尼是解决LCL滤波器谐振问题的有效措施,传统的电容电流反馈有源阻尼方法需要增加额外的电流传感器,并网电流反馈有源阻尼存在微分信号提取困难等问题。为此,提出基于线性自抗扰技术(linear active disturbance rejection control,LADRC)的LCL逆变器并网电流控制及有源阻尼策略。基于LCL滤波器数学模型,设计三阶LADRC并网电流控制器,分析LADRC的跟踪和抗扰能力;将扩张状态观测器(extend state observer,ESO)得到的并网电流微分及二阶微分观测信号作为有源阻尼反馈量,以实现基于并网电流微分反馈的谐振抑制目标,避免了传统直接求取电流微分带来的噪声等问题。仿真和实验结果证明了本文所提策略的有效性。

Active damping is an effective way to eliminate resonance of LCL type inverter. However, active damping method based on traditional capacitive current feedback needs additional current sensors, while the method of grid current feedback has difficulties in extracting differential signals.Therefore, a grid current control and active damping strategy of LCL type inverter based on linear active disturbance rejection control(LADRC) were proposed in this paper. Firstly, a third-order LADRC grid current controller was designed, to help improvement of system anti-disturbance ability. Thanks to LADRC strategy, the differential and second-order differential signals of grid current, used in active damping feedback channels to realize the resonance suppression target, could be obtained from the extended state observer(ESO) easily,avoiding problems of direct differentiation. Simulation and experimental results demonstrated effectiveness of proposed strategy.