Design of Fractional Order Controller for Microgrid Based on Model Analysis

With the development of power electronics technology, people pay more attention to power quality. In order to stabilize the current and voltage of AC side in microgrid, a control strategy based on PWM technology is proposed. D-q transformation is usually used to solve the problem of three-phase variable muti-coupling. According to the decoupled mathematical model, PWM control strategy is divided into inner loop current control and outer loop voltage control. PI controller is usually used to control the inner loop current and outer loop voltage. However, the dynamic characteristics and robustness of the traditional PI control system has been gradually unable to meet the requirements of complex power grid. In order to improve the dynamic characteristics and robustness of the system, the inner loop current is controlled by fractional order controller based on internal model control, fractional order PI controller is used to control the outer loop voltage. The fractional order controller has strong robustness, but its parameters are difficult to be solved. In this paper, a method of fractional order PID parameter tuning based on model analysis is proposed. Compared with the traditional integer-order PI controller, the fractional-order controller has stronger robustness, can overcome the problem of model accuracy to a certain extent, and has better control performance. Finally, the simulation results show the effectiveness of the proposed method.