The impacts of control systems on hybrid energy storage systems in remote DC-Microgrid system: A comparative study between PI and super twisting sliding mode controllers

Abstract

The adoption of hybridized energy storage systems (HESSs) in standalone photovoltaic (PV) systems instead of single battery ESSs offers featured capabilities of high power/energy densities and extended lifespans to supply power through controllable power converters using robust controllers. This paper examines the HESS control subjected to pulsed power balance changes through splitting frequency parts of load requirements among battery and supercapacitor. The filtering-based frequency decoupling method ensures sharing control of HESS currents using a dual-loop structure with high control dynamic to track battery currents considering Bus voltage abnormalities, and a hysteresis current controller (HCC) to command supercapacitor currents using battery current setpoints. Three settings are used to assess the superior performance of the HESS: combining Proportional-Integral (PI) with Super-twisting sliding mode (STSMC) controllers in dual-loop control structures, time-constants, and current bandwidths of the HCC. Upon competitive findings, the optimal settings approve minimum Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE) of bus voltage, HESS currents, power deficits, besides load-meeting rates. The STSMC outperforms due to its super-spiral curve offering rapid convergence and reduced chattering that influences the stability in conventional SM. Then, less stressed and smooth behavior of the HESS, stable bus voltage, smooth power flowing, and high load sharing efficiency are achieved.