LCL型并网逆变器的滑模变结构控制策略

Sliding Mode Variable-structure Control Strategy for Grid-connected Inverter with LCL Filter

针对三相并网分布式发电系统的运行特点以及LCL滤波器的工作特性,建立三相并网逆变器的数学模型,它在同步旋转dq坐标系下的数学模型,反映出LCL型并网逆变器是一个强耦合的、非线性的系统。为解决对这个强耦合、非线性系统直接设计控制器的困难,采用逆系统方法,将原系统线性化且解耦,构造出一个伪线性系统;然后,运用滑模变结构控制,针对构造出的这个伪线性系统,设计该系统的控制策略以实现对LCL型并网逆变器综合控制;最后在Matlab/Simulink仿真软件中通过建立仿真试验模型进行仿真,仿真的结果验证了所提出的这种控制策略的有效性和较强的鲁棒性。

According to the operating characteristics of three - phase grid - connected distributed generation system and the work characteristics of LCL filter, the mathematical model of three - phase grid - connected inverter is established. Its mathe-matical model in a synchronous rotating dq coordinate system reflects that it is a strong coupling nonlinear system. To avoid the difficulties in designing the controllers for the system, an inverse - system control is proposed. Firstly, using the inverse - sys-tem method, the original system is linearized and decoupled into a pseudo - linear system. Secondly, employing the variable - structure control （VSC） theory, the variable - structure controllers of the pseudo - linear system is designed for controlling the system of grid - connected inverter with LCL filter. Finally, the feasibility and effectiveness of the proposed control strategy are verified by the simulations on Matlab/Simulink.