A hybrid adaptive droop control technique with embedded DC-bus voltage regulation for single-phase microgrids

Abstract

This paper presents a novel hybrid adaptive droop controller to simultaneously regulate both the AC-side and DC-side parameters for power electronic converters in single-phase Microgrids. The main contribution of this paper is to integrate the AC-side and DC-side controllers. Unlike previously presented control schemes, where the DC-bus is considered as an infinite bus or constant voltage bus, the proposed control method incorporates the dynamics of the DC-side while regulating voltage and frequency at the AC-side. Designing the control scheme in single-phase is challenging due to the existence of double-frequency ripples in DC-bus voltage and converter output active/reactive power signals. In order to improve the transient performance of the proposed controller, two adaptive estimators have been used to estimate the real-time values of DC-bus voltage and output active/reactive power signals without the need to add low-pass filters. This controller can provide a tightly regulated voltage required for critical loads in MGs while improving the transient response in both DC and AC side. Simulation and experimental results in a single-phase islanded Microgrid show the superior performance of the proposed control scheme in regulating the desired parameters in AC and DC side in comparison with the conventional droop-based controllers.