Enhancing hybrid energy storage systems with advanced low-pass filtration and frequency decoupling for optimal power allocation and reliability of cluster of DC-microgrids

This study introduces an innovative power-split approach for hybrid energy storage systems (HESS) and diesel generators, utilizing frequency decoupling and a combination of classical and advanced low-pass-filtration techniques. The HESS dual-loop structure incorporates Super-Twisting-Sliding-Mode-Control, known for its remarkable robustness against uncertainties and external disturbances, effectively suppressing chattering. Among the low-pass-filtration techniques, Advanced Low-Pass-Filtering (ALPF) surpasses Classical Low-PassFiltering (CLPF), offering enhanced control statistics. The regulation of supercapacitor setpoint current based on the bank voltage ratio and control inaccuracy of battery current enables the ALPF to address dynamic battery issues. Under three waveforms, thorough simulations show superior load power allocation performance. Smoother waveforms boost supply voltage by 36% and power flow by 0.2%. Root-Mean-Squared-Error and Mean-Absolute-Error evaluations show exceptionally low average errors of 0.72% for Bus voltage, 0.16 A for battery current, and 3 A for supercapacitor current. The system also achieves 99.8% supply efficiency with a load setpoint deviation of less than 1%. ALPF improves supercapacitor performance by 8.4-11% while adjusting for uncompensated battery power. ALPF improves voltage regulation, power losses, load setpoint convergence, power peaks, and recovery. Ultimately, the proposed low-pass-filtration technique significantly enhances system dependability, relieving the burden on HESS while achieving superior loading efficiency.