The parameters optimization and stable boundary expansion method of current controller for VSC to avoid low frequency oscillations

Abstract

The low frequency oscillations that are raised by the interactions between the voltage source converter (VSC) and the weak grid, are becoming a critical threat to power system stability. Identifying the proper parameters for VSC is essential for preventing the appearance of oscillation in advance. To achieve this target, this paper proposes a quantitative evaluation method for the system’s stability to clarify the stable boundary of current control parameters. Then, an active damping controller is proposed and supplemented in the control of VSC, to expand the stable boundary of current control parameters. Thus, the VSC can stably operate within a wider range of parameters selection, the oscillation can be damped without weakening the dynamic control capability of the VSC. The simulation tests are performed to verify the correctness of the quantitative evaluation method and the effectiveness of the proposed stability boundary expansion control.

Keywords

• Weak grid
• Voltage source converter
• Active damping
• Stable boundary