Active damping control of multi-scale oscillations in new energy grid connection considering wideband negative resistance characteristics

• Multi-scale Oscillation Identification and Control. • Accurate oscillation identification and division. • Multi-parameter optimization calculation. • Controller design and optimization. Due to the stochasticity and complexity of renewable energy grid-connected systems, conventional control methods are limited to single-frequency-point regulation and lack broadband adaptability, making it difficult to effectively suppress wideband oscillations and resulting in unsatisfactory control performance. To address this challenge, this paper proposes an active damping control method for multi-scale oscillations in renewable energy grid-connected systems, incorporating wideband negative resistance characteristics. Based on an analysis of the system's wideband negative resistance behavior, a negative resistance characteristic model of power electronic converters and an approximate function for grid-connected oscillations are established. By computing the identification index of oscillation signals, different grid-connected oscillation states can be classified. Subsequently, key active damping control parameters, including the gain coefficient and phase compensation coefficient, are derived. The active damping parameters are determined by evaluating the damping ratio of the grid-connected system. Using these calculated parameters, an active damping oscillation controller is designed. The feedback coefficient is optimized to enhance controller performance, achieving more precise control. Experimental results demonstrate that the proposed method significantly reduces oscillation amplitude, with an average attenuation rate of 52.69 % across a wide frequency range. Additionally, it narrows the system's oscillation frequency from 2.09-2.69 Hz (typical in conventional methods) to 1.27 Hz while increasing the damping ratio to 0.65, outperforming existing control strategies. The key contribution of this work lies in bridging the research gap in dynamic parameter adaptation for multi-scale oscillations and enabling wideband cooperative suppression, offering a comprehensive solution for the stable and efficient operation of renewable energy grid-connected systems and presenting a novel framework for addressing complex power system oscillation challenges.