基于多滑模变结构的双向并网变换器虚拟惯性控制策略

Virtual Inertia Control Strategy of Bidirectional Grid-Connected Converter Applying Multiple Sliding Mode Variable Structure Control

针对直流微电网惯性低、母线电压抗干扰能力差的问题,以双向并网变换器为控制对象,提出一种基于多滑模变结构的虚拟惯性控制策略。内环采用基于指数趋近律的滑模电流控制,快速跟踪并网电流给定值,提高系统的响应速度。外环建立虚拟惯性控制方程与电压滑模面结构,增强直流微电网的惯性,平抑直流母线电压波动。通过小信号扰动法和Nyquist判据证明了双向并网变换器在所提控制策略下的稳定性。最后,搭建了相应的仿真模型和StarSim HIL硬件在环实验平台。仿真及实验结果表明,与基于PI控制和无源控制的虚拟惯性控制策略相比,文章所提控制策略具有更好的动态、静态特性,提高了直流母线电压的稳定性。

Aiming at the problems of low inertia and poor anti-interference ability of bus voltage in DC microgrid, a virtual inertia control strategy based on multiple sliding mode variable structure control is proposed in this paper. Sliding mode current control based on the index reaching law is adopted in the inner loop, which can quickly track the given value of grid-connected current and improve the response speed of the system. Virtual inertia control equation and voltage sliding mode surface structure are established in the outer loop to enhance the inertia of the DC microgrid and suppress the fluctuation of the DC bus voltage. The stability of bidirectional grid-connected converter under the proposed control strategy is proved by small-signal disturbance method and Nyquist criterion. Finally, the corresponding simulation model and StarSim HIL hardware-in-the-loop experimental platform are built. The results show that, compared with the traditional virtual inertia control strategy based on PI control and passivity-based control, the proposed control strategy has better dynamic and static characteristics, and improves the stability of the DC bus voltage.