A New DC Microgrid Voltage Regulation Control Strategy for Photovoltaic Power Plant Based on Variable Power Reserve Level

Abstract

With the gradual increase of photovoltaic power penetration, in order to ensure the voltage quality of DC micro-grid, photovoltaic power plants need to be able to participate in voltage regulation tasks to cope with the impact of photovoltaic power fluctuations and load fluctuations on voltage quality. Researches show photovoltaic power plants under load-reduction operation can participate in voltage regulation without using energy storage equipment. In this paper, a photovoltaic voltage regulation control strategy with variable load-reduction rate considering photovoltaic power fluctuation is proposed, which can change the load-reduction rate of photovoltaic plants according to the fluctuation of photovoltaic. Then, aiming at the problem of fast voltage change caused by small inertia time constant of DC micro-grid, the method of using photovoltaic backup capacity to provide inertia control for the system is adopted, so that photovoltaic power plants can cope with both photovoltaic fluctuation and load fluctuation at the same time. Finally, a simulation model is established in PSCAD/EMTDC. Simulation results verify that under the proposed control strategy, grid-connected converters for the PV can participate in the DC voltage regulation.