两级式光伏逆变器的中间直流母线电压的稳定性是光伏逆变器良好的发电质量和长期运行的关键。光伏逆变器的发电功率易受到光照强度、温度等环境因素的影响，该功率波动会在直流母线电压上产生较大扰动。为了提升直流母线电压的抗扰性，改善逆变器的控制性能，提出了一种基于改进一阶线性自抗扰控制（LADRC）的光伏逆变器母线电压控制策略。采用改进一阶LADRC对逆变器双环控制中的电压外环控制器进行设计。在传统LADRC的线性扩张状态观测器的基础上，将状态变量表达式中系统控制量的分量去除，使得状态变量的观测误差方程中只含有与系统输入量相关的误差分量，减小了状态变量的观测误差。新增状态变量并引入前一控制周期的系统控制量，根据总和扰动表达式对总和扰动重新进行估计并补偿。在频域上对改进LADRC的控制性能进行分析，相较传统LADRC而言，改进LADRC的系统带宽增大，动态跟踪能力增强，在中低频段具有更小的扰动增益。仿真和试验表明改进LADRC具有更短的调节时间，系统动态性能具有较好的提升，直流母线电压的抗扰性增强。

The stability of the intermediate DC-bus voltage of the two-stage photovoltaic inverter is crucial for its good power generating quality and long-term operation. The power generation of photovoltaic inverters is easily affected by environmental factors such as the strength of illumination and temperature, and this power fluctuation can cause significant disturbance on the DC-bus voltage. In order to improve the disturbance resistance of the DC-bus voltage and the control performance of the inverter, a photovoltaic inverter bus voltage control strategy based on improved first-order linear active disturbance rejection control (LADRC) is proposed. The voltage outer loop controller in the dual loop control of the inverter is designed by using improved first-order LADRC. On the basis of the traditional LADRC linear extended state observer, the system control component in the expression of the state variable is removed, so that the observation error equation of the state variable only contains error components related to the system input, which reduces the observation error of the state variable. A new state variable is added and the system control quantity of the previous control cycle is introduced, and total disturbance is re-estimated and compensated based on the total disturbance expression. The control performance of improved LADRC is analyzed in the frequency domain. Compared with the traditional LADRC, the improved LADRC has an increased system bandwidth, enhanced dynamic tracking ability, and smaller disturbance gain in the mid to low frequency range. Simulation and experiments show that the improved LADRC has a shorter regulating time, better system dynamic performance, and the disturbance resistance ability of DC-bus voltage is enhanced.

广东省自然科学基金项目(2021A1515012616)