A Novel Event-Triggered-Control Based Distributed Voltage Control Strategy for Photovoltaic Sources in Dc Microgrids

Abstract

DC microgrids are highly compatible with photovoltaic generation due to their direct current properties. To optimize solar energy extraction, PV sources commonly operate under the maximum power point tracking control. However, as PV installation increases exponentially, traditional MPPT algorithms may cause issues like power fluctuations and voltage deviations, posing voltage stability challenges due to the inherent intermittency and variability of solar resource. Therefore, to reduce investment and maintenance costs of storage systems, innovative control methods are needed for PVs to provide DC-bus voltage regulation (DVR) services. This study proposes a hierarchical control framework enabling PVs in DC microgrids to participate in DVR. For primary control, the proposed control strategy utilizes dp/dv as a characteristic control variable, avoiding complicated calculations and unifies DVR and MPPT into a single control structure, allowing the PV source to operate in either MPPT mode if the DC bus is at its nominal value, or DVR mode if the DC-bus voltage exceeds it. The transition between MPPT and DVR is autonomous and seamless. An event-triggered secondary control strategy is implemented to ensure generation fairness and multi-source coordination among PVs and reduce the communication burden. The effectiveness and feasibility of this approach are validated through MATLAB/Simulink simulation.

Keywords: DC Microgrids, photovoltaic sources, distributed secondary control, DC-bus voltage regulation.