A bifunctional utility connected photovoltaic system with power factor correction and UPS facility

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic (PV) system is connected in parallel between the utility and load. The PV system provides an uninterruptable voltage to the load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system: harmonic elimination function; feeding the photovoltaic energy to the utility; and providing the uninterruptible power source battery to the load. In the case where the photovoltaic array system is in a state of poor power generation, the battery and capacitor of the PV system are charged by a three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to the load and reactive power to the utility in order to maintain the unity power factor and to regulate AC load voltage