Coordinated Control Strategy for Photovoltaic/Battery Micro-grid

In the future, the penetration rate of new energy will gradually increase in the power system. Therefore, the study on the micro-grid with new energy as the main energy supply will be a hot spot. As the most convenient and clean energy form, photovoltaic power generation is becoming the main energy supply in micro grid system. As a key carrier to balance the power fluctuation in micro-grid, energy storage unit is also a hot research topic. This paper mainly studies the structure and control strategy of photovoltaic/battery microgrid system. The system structure and topology of photovoltaic/battery micro-grid are established. A modified variable step length incremental conductance (INC) method is adopted in this article to adapt different environments by designing new velocity factors. Control of DC bus voltage is maintained by the droop control based on the energy storage unit in island mode. In order to reduce the impact to the system equipment in grid-connected time, a secondary control strategy of DC bus voltage is proposed. Adding the deviation compensation term of DC bus voltage to droop control, can achieve DC bus voltage regulation in island mode and realize the seamless switching of grid/off-grid pattern. The simulation results verify the effectiveness of the proposed control strategy.