Voltage control of distribution network with photovoltaic power generation systems

A voltage control system composed of grid-connected photovoltaic (PV) inverters and on-load tap changing transformer (OLTC) is proposed to solve the voltage limit problem arisen from high-penetration distributed PV power generation system integrated into the distribution network. PV inverters, as a part of grid voltage control system, are able to control the reactive power based on the voltage amplitude. In the case when PV inverters failed to normalize the grid voltage, OLTC tap controller is used as an alternative. In this case, the tap of OLTC tap controller will change accordingly based on the maximum and minimum voltage estimated from phasor measurement unit (PMU) placed at key nodes in the grid. The validity of the voltage control system proposed in this paper is verified by detailed simulation and solid results.