基于改进二阶线性自抗扰技术的微网逆变器电压控制

微网逆变系统具有非线性、强耦合、负载扰动强、并/离网模式切换灵活等特性,传统电压电流双环控制难以取得满意的控制效果。自抗扰策略将影响系统控制的不确定因素视为总和扰动予以估计和补偿,可将复杂系统校正为积分串联型以获取期望的控制性能。文中引入更具工程应用价值的线性自抗扰控制(LADRC)技术,设计以输出电压及其微分为状态变量的二阶LADRC。考虑到扩张状态观测器(ESO)是影响LADRC控制性能的核心环节,在ESO中引入输出电压误差微分项,以提高ESO的扰动观测能力;在总和扰动作用通道增加一阶惯性环节,避免观测带宽增加而引入噪声。对LADRC及典型双闭环控制系统的频率响应特性进行分析可知,改进后的LADRC较双环控制及传统LADRC具有更好的抗扰性能。仿真和实验结果证明了所提策略的有效性。

Voltage Control of Microgrid Inverter Based on Improved Second-order Linear Active Disturbance Rejection Control

The microgrid inverter system is characterized by nonlinearity, strong coupling, violent disturbance and flexible switching mode. It is not easy to meet requirements through conventional dual loop control. As for the active disturbance rejection control(ADRC), all uncertainties of the system are regarded as total disturbances, which will be estimated and compensated dynamically. As a result, the complex system can be corrected to integral series type to achieve expected control performance. With the adoption of linear active disturbance rejection control(LADRC)technology with more engineering application value, this paper designs a second-order LADRC controller which takes the output voltage and its differential as state variables. Considering that the extended state observer(ESO)is the core of LADRC, the output voltage error derivative term is introduced to improve the observation capability of ESO. Further, a first-order inertial link is embedded into the total perturbation channel to avoid increasing observation noise. Frequency response characteristics of LADRC and typical dual loop control system show that the improved LADRC has a better disturbance rejection performance than the other two. Simulation and experimental results further prove the effectiveness of the proposed strategy.