A Solving-Equation-Based Analysis Method to Obtain Maximal Damping Ability for High-Order Grid-Connected Inverter

Due to higher elimination ability of switching frequency ripple and lower inductor volume, grid-connected inverter with LCL filter is commonly utilized when it is compared by that with L filter. However, high-order grid-connected inverter may bring resonance issue easily. To address this issue, this paper is dedicated to obtaining maximal damping ability for high-order grid-connected inverter via a solving-equation-based analysis method. Firstly, a discrete-domain expression of high-order grid-connected inverter is derived. Secondly, the damping characteristics based on the derived expression are analyzed in detail by combining multiple influence factors simultaneously. Furthermore, to obtain the largest damping ability, the maximal damping ratio (MDR) curve is also given in order to provide a guideline to design controller parameters in practice. Finally, the proposed analysis method is verified by simulation results.