Voltage control of unbalanced three-phase networks using reactive power capability of distributed single-phase PV generators.

In this paper, a developed voltage control method for distributed single-phase photovoltaic (PV) generators in unbalanced distribution networks is proposed. The reactive power capability of the PV inverters has been used to regulate bus voltages during irradiance or load variations. The amount of the reactive power required to optimize phase voltages is calculated using fuzzy logic control function, and hence, the power factor is precisely determined. The proposed control for the PV inverters is based on the dq-current control to regulate the DC bus voltage and the amount of the reactive power. A hysteresis current control is used as a pulse width modulation gate generator. The proposed control precisely determines the amount of the required reactive power to regulate the system bus voltages to lie within standard limits. The efficiency of the proposed control is evaluated with a 10-node, 5 kV/phase unbalanced three phase distribution system. The analysis includes different test cases under transient and steady state operations to ensure accurate representation of the actual system. The obtained results assess the quality of the network voltages of the studied system regarding voltage levels and the degree of the unbalance. Moreover, the proposed control is capable of operation under different power factors of the PV inverter. [ABSTRACT FROM AUTHOR]