An intelligent sliding mode control for stabilization of parallel converters feeding CPLs in DC‐microgrid

Abstract

The constant power loads (CPLs) threaten the stability of the DC microgrids (DCMGs) due to the negative impedance characteristic, which leads to voltage oscillations or a blackout in the DCMG. This paper proposes a new droop control for paralleled DC–DC converters feeding CPLs in the DCMG to improve the stability of the whole system. In this approach, an optimization droop gain is conducted for each converter to guarantee current sharing among paralleled converters. Furthermore, an intelligent single input interval type-II fuzzy logic controller (SIT2-FLC) is developed in a model-free framework to further ameliorate the current sharing and voltage regulation in the DCMG when supplying the CPLs. An extended-state observer (ESO) is adopted in the model-free controller to estimate the unmodelled dynamics in the DC-DC converters feeding CPLs. Since an estimation observer error often appears in the presence of uncertainties, a sliding mode control (SMC) technique is proposed to remove the estimation error and enhance the system stability. The studied DCMG is developed in hardware-in-the-loop (HIL) with various levels of CPL's power to verify the applicability of the suggested mode-free intelligent controller.