Study on reactive power control of large-scale photovoltaic system for voltage regulation with long distribution line

Constant power factor control of a power conditioning system in a large-scale photovoltaic generation system (PV system), such as a mega-solar system, is introduced to mitigate voltage variations on a distribution line. However, it is difficult for the control to mitigate the voltage variation on a long distribution line because of the loss on the distribution line. This paper proposes an advanced reactive power control, in which the power factor of the PV system is adjusted both by output power of the PV system and by apparent power of loads not to minimize the voltage variation at the interconnection point but to minimize the voltage variation over the whole distribution line, and reports the result examined by numerical analysis about mitigating the voltage variation by applying the control. This paper shows that the proposed control can mitigate the voltage variation more than constant power factor control and there is a probability that it will be applied as a measure of suppressing the voltage variation on the long distribution line.