Inductor-Current Proportional-Derivative Feedback Active Damping for Voltage-Controlled VSCs

To damp the resonance, inductor-current proportional feedback has been generally adopted in voltage-controlled voltage-source converters. When the voltage controller is implemented with the basic proportional-resonant (PR) regulator, it is observed that the system bandwidth is restricted, resulting in a poor dynamic performance, especially in the case of low sampling frequency. However, the essence of low bandwidth remains unknown. This paper thus attempts to clarify this essence and devotes to tackle the low bandwidth issue. The root cause is revealed that the time delay jeopardizes the damping performance of inductor-current proportional feedback. To ensure the sufficient gain margin, the proportional gain of PR regulator thus has to be limited, leading to low bandwidth. Then, an inductor-current proportional-derivative (PD) feedback active damping method is proposed, which can strengthen damping effect as well as the dynamic performance of the system. Finally, simulation results validate the effectiveness of the proposed control strategy.