Research On Grid Connected Control Of PV And Battery Micro-Grid With Dynamic Reactive Power Compensation

Distributed photovoltaic generation has gradually become the effective supplement to the traditional power grid due to it’s advantages such as less environment pollution, more flexible and easy to maintain and renewable. This paper takes the micro-grid which is composed of distributed photovoltaic power, energy storage battery and local load as the research object to deal with the random change of illumination and weather cause photovoltaic output power fluctuation and large-scale grid connected photovoltaic affect safe and stable operation of power grids.Firstly, the working principle of three-phase pv and battery microgrid is introduced and mathematical model is established. The maximum power tracking control methods of dual-stage PV grid-connected system with the charge and discharge control strategy of energy storage battery which are based on battery SOC state have been researched. And the flow of system power is introduced detaily. The stable operation of the system and the voltage stability of DC bus as the energy exchange intermediary can be maintained effectively through changing the methods of each part.Then for the grid connected inverter in microgrid system, the principle of traditional voltage oriented vector control and the influence on PCC voltage are analyzed. A power control strategy with dynamic reactive power compensation based on abc natural coordinates is proposed in this paper. According to the principle of vector control inverter based on virtual flux orientation, re-modeling the inverter by duty-cycle. And putting forward a grid connected inverter control strategy based on improved virtual flux oriented with voltage sensorless, it can achieve both grid-connected generation and reactive power compensation. The control system failure caused by the voltage sensor fault problem also can be overcomed.Finally, the two control strategies are verified in the experimental platform of pv and battery micro-grid which is grid-connected based on dSPACE. The experiment results show that, double loop power control in natural coordinate can realize control of active and reactive power independently without any coordinate transformation and phase locked loop。Without the AC side voltage sensor, control system can still work effectively to further improve the stability of the system.