An adaptive control strategy for parallel operated photovoltaic inverters

Nowadays, micro-gird is drawing great concerns, because it exerts the advantage of renewable energy generation, at the same time it is compatible with the public grid. This paper proposes a control strategy for parallel operated photovoltaic (PV) inverters under off-grid condition. It is essentially developed for the micro-grid with dominated power supplied by PV generation. During isolated from the public grid, the AC grid-tied PV inverters can be controlled by constant voltage amplitude and P-f droop method. All the reactive power and part of the active power that the main AC grid needed can be provided by the master inverter which connects the storages and main AC grid. To overcome the severe shortcoming of power fluctuation induced by the unstable PV generation, the AC grid-tied PV inverters provide only active power and they are controlled by an adaptive droop control method. The output power of AC grid-tied PV inverters varies matching to the maximum power of PV generation. The MATLAB simulation proved the correctness and feasibility of the control method proposed above.