Active Disturbance Rejection Control Based Control Strategy for Virtual Synchronous Generators

Abstract

To make the distributed generation provide better support for microgrid, the idea of virtual synchronous generator (VSG) is proposed. Typically, the VSG consists of the outer power loop and the inner cascaded voltage and current control loops. Due to the three-loop cascaded structure, a voltage loop with higher bandwidth is significant for ensuring good power control performance. Moreover, most loads in the microgrid are variable and nonlinear. So the voltage control scheme must possess strong robustness against load disturbance. A linear active disturbance rejection control (LADRC) scheme based on the improved error feedback control law (IEFCL) is proposed for VSG voltage control. Compared with the traditional EFCL, the proposed IEFCL can effectively improve the gain and compensate phase lag in the midfrequency, thereby increasing the bandwidth of the LADRC based voltage loop. Quantitative analysis demonstrates the proposed scheme can achieve highly decoupled voltage control in dq frame. In comparison with the traditional strategies, the proposed scheme has higher bandwidth and can significantly improve the power control dynamics for VSG in parallel operation. Additionally, it possesses a good capability of harmonic mitigation and strong robustness against load disturbance. Simulations and experiments verify the effectiveness of the proposed scheme.