Improved master-slave voltage and active power control strategy for multiple grid-connected inverters

In the microgrid with high penetration rate of renewable energy, multiple distributed generations operate in parallel. To ensure stable operation of the microgrid, research for multi-inverter coordination control is necessary. Master-slave control can realize various functions with the combination of different control strategies. Voltage and active power control strategy can provide voltage support for the grid and reduce the voltage fluctuation in the point of common coupling. Previous voltage-supporting methods are usually based on constant droop coefficient, where the control curve is linear. When the voltage fluctuation is too large, the change of the distributed generations power is too small to support the gird voltage. This paper presented an improved master-slave voltage and active power control strategy for multiple photovoltaic inverters. The master inverter operates under maximum power point tracking control strategy as the sample. The slave inverter adopts nonlinear voltage and active power control. When the voltage is too high, increase the droop coefficient to accelerate the power reduction. Conversely, when the voltage is much below the rated value, the distributed power supply will output its maximum power. Finally, the effectiveness of the proposed control strategy is verified by simulation.