An Improved Capacitor Current Active Damping Based on Parallel Feed-Forward Compensation Method for LCL Filtered Grid Connected Inverter

Abstract

This paper presents an Active Damping (AD) of filter capacitor current for LCL three-phase Grid Connected Inverter (GCI). In this method, an improved damper is added across the LCL filter and capacitor current feedback. This combination forms a damping loop which is applied at a reference voltage point. The key features of this configuration are faster dynamic response and high control bandwidth as compared to capacitor current proportionally feedback and conventional Parallel Feed-Forward Compensation (PFC) methods. Moreover, with the proposed method the region of frequency within which the harmonic compensation is effective can be extended beyond the gain crossover frequency. The stability effect of current control loop has been evaluated by employing the proposed method under the filter parametric variations. Furthermore, this paper illustrates the stability, dynamic, and transient responses through Simulation to validate the effectiveness of the proposed method.