Numerical analysis of voltage regulation via smart PV inverters

Significant reductions in the manufacturing cost of PV panels combined with attractive feed-in tariff programs are driving a rapid increase in the penetration of customer-owned PV installations. High penetration of PV on distribution feeders has been observed to cause voltage regulation problems in actual field installations. The concept of the “smart” PV inverter has been proposed to mitigate this problem by injecting or absorbing reactive power (VARs). Several methods have been proposed to control such inverters. This paper compares two such methods, feedforward and feedback. Results show that the inverter´s efficiency at regulating voltage in terms of VARs absorbed is improved with feedback control. More significant is that the feeder voltage under the feedforward method is sensitive to the choice of tuning parameter. While the feedback method is more robust, existing literature indicates that improper parameter selection results in an unstable system, preventing the inverters from effectively regulating voltage.