A Capacitor Current Feedback Compensation Strategy for Enhancing Resonance Suppression Capability

Abstract

Against the backdrop of high proportions of renewable energy and 
power electronic equipment, resonance stability has emerged as a critical issue. 
This paper takes grid-forming inverter (GFMI) as the research object, considering 
that the internal digital delay will affect the inner-loop self-stability of the 
inverter, the double-loop of the GFMI is modeled and analyzed in the discrete 
domain to obtain the fastest dynamic performance and the optimal damping ratio. 
In addition, aiming at the external resonance problem of the interaction between 
the inverter and the grid impedance, a mapping model reflecting the effect of 
harmonic voltage disturbance of the inverter and the grid on the resonance 
excitation of the grid-connected current is established, and a capacitor current 
feedback compensation (CCFC) resonance suppression strategy is proposed to 
enhance the damping capacity of the system. The simulation results indicate that 
the proposed strategy significantly suppresses the resonance phenomenon of the 
system and improves the power quality.