Optimized Design of LCL Filters for Single-Phase Grid-Connected Inverter Systems using Advanced Optimization Techniques

The traditional approach of manually selecting the parameters for LCL filters employed in single-phase grid-tied inverters is often ineffective and challenging to optimize. This can result in the LCL filter being unable to adequately attenuate high-frequency harmonics, causing the grid-injected current to not fully comply with IEEE 519 standards. Furthermore, the filtering performance can degrade when the system is coupled to a weak grid due to the inherent resonance issue of the LCL filter. To address these problems, this paper thoroughly examines the total harmonic distortion (THD) and resonance frequency of an LCL-filtered grid-tied inverter. An optimization function with three different constraints is developed. Several advanced optimization techniques, including particle swarm optimization (PSO), whale optimization algorithm (WOA), and grey wolf optimization (GWO), are applied and compared extensively. The computational and simulation results, analyzed under different operating conditions, demonstrate that PSO outperforms the other examined optimization methods by improving the effectiveness, robustness, and reliability of the LCL filter while also minimizing the THD.