基于线性自抗扰控制的微网逆变器时-频电压控制策略

微网是一个非线性、强耦合、多约束、负载扰动大的系统,传统比例-积分(PI)双环控制已经无法满足需求,自抗扰技术通过补偿扰动可使微网逆变控制系统的性能显著改善。据此,文中提出了基于线性自抗扰控制(LADRC)的微网逆变器时-频电压控制策略。为了提高微网逆变器的抗扰性能和动态性能,在时域上,设计和分析了dq轴解耦环节、带电容电流反馈的降维扩张状态观测器以及线性状态误差反馈控制律;为了提高微网逆变器在各谐波频率处的跟踪精度和抗扰性能,分析了时域LADRC系统的频率响应特性,并据此设计和分析了频域上的实部/虚部解耦环节和时-频域LADRC策略。最后,针对工作在孤岛模式下的微网逆变器,对所提策略进行了实验验证。实验结果表明,与PI双环控制对比,基于LADRC的微网逆变器时-频电压控制策略具有更好的解耦、抗扰、动态性能,并能精确控制谐波电压以达到抑制谐波的效果。

Time-Frequency Voltage Control Strategy of Microgrid Inverter Based on Linear Active Disturbance Rejection Control

Microgrid is a nonlinear and strong coupling system with multiple constraints and large load disturbance. The conventional proportional-integral (PI) dual-loop control has been unable to meet requirements. The active disturbance rejection control (ADRC) technology can significantly improve the performance of microgrid inverter control system by compensating the disturbances. This paper proposes a time-frequency voltage control strategy of microgrid inverter based on linear active disturbance rejection control (LADRC). In order to improve anti-disturbance and dynamic performances of microgrid inverter, the decoupling of dq axis, the dimension-reduced extend state observer (ESO) with capacitive current and the linear state error feedback control law are designed and analyzed in the time domain. In order to improve the tracking accuracy and anti-disturbance performance of microgrid inverter at various harmonic frequencies, the frequency response characteristics of time-domain LADRC system are analyzed. Based on it, the real and imaginary decoupling links and the time-frequency domain LADRC strategy are designed and analyzed. Finally, the proposed strategy is verified by experiments for the microgrid inverter operating in the island mode. Experimental results show that the time-frequency voltage control strategy of microgrid inverter based on LADRC has better decoupling, anti-disturbance and dynamic performance when it is compared with PI double-loop control. Moreover, it can accurately control harmonic voltage to achieve harmonic suppression.