Distributed generation control strategy towards AC-DC hybrid stability analysis

Abstract

The uncertainties associated with renewable Distributed Generation (DG) and distribution networks present significant challenges for researchers. DG systems, which integrate various renewable energy sources (RES), which consist of photovoltaics, wind turbines, hydrogen cells, and micro-turbines, are appealing in terms of economic and environmental advantages. Modular structural inverters are commonly used in DG, representing a new generation of systems that will soon integrate networks of RES. However, the modular structure and the integration of both AC and DC sources bring about stability challenges that must be pointed out. At the distribution substation, solar photovoltaic (PV) panels, microturbines, wind turbines, and hydrogen cells are connected to form a grid system known as DG. The integration of multiple RES, whether DC or AC, makes DG an attractive option due to its numerous economic and environmental benefits. This research proposes an inverter control mechanism that combines Quantitative Feedback Theory (QFT) and Maximum Power Point Tracker (MPPT) control to overcome uncertainties and ensure efficient controllability and stability in AC-DC hybrid DG systems. This research proposes a novel inverter control mechanism that can efficiently manage the output of power output and stability of an AC-DC hybrid MG system. In the simulation process, the simulation model was divided into several segmental modules interconnected with a controller. In this approach, the proposed inverter mechanism can connect both DC and AC modular RES and convert them to a fixed 400V DC. The Maximum Power Point Tracking (MPPT) control method is then applied to optimize the output power, while the Quantitative Feedback Theory (QFT) control mechanism adjusts power based on the demands from distributed generation (DG) or ESS. The excess power is stored in the energy storage systems if there is no immediate demand. The proposed model was simulated using MATLAB, and the results demonstrate the control strategy effect in maintaining grid stability and maximizing power output, outperforming the benchmark studies from RES. The innovation of this research lies in developing a comprehensive control mechanism capable of effectively managing the complexities of a modular structured RES microgrid system. The total harmonic distortion (THD) analysis is being conducted, keeping the THD percentage minimal. The research found the THD to be 3.80%, which is below the 5.00% standard, aligning with established norms. The proposed control strategy has proven its ability to point out the challenges due to uncertainties in renewable energy systems, making it a promising solution for integrating DG into the power grid.