Droop-based active power curtailment for overvoltage prevention in grid connected PV inverters

Photovoltaics (PV) is considered a non-controllable power source which can create overvoltages in distribution feeders during periods of high generation and low load. This is usually prevented by limiting the penetration level of PV to very conservative values, even if the critical periods rarely occur. This paper discusses the use of droop based active power curtailment (APC) techniques for overvoltage prevention in radial low voltage (LV) feeders as a means for increasing the installed PV capacity and energy yield. Two schemes are considered and tested in a typical 240V/75kVA Canadian suburban distribution feeder with 12 houses equipped with roof-top PV systems. In the first scheme, all PV inverters have the same droop coefficients. In the second, the droop coefficients are proposed to be different so as to share the total active power curtailed, and consequent loss of revenue, among all PV inverters/houses. Simulation results demonstrate the effectiveness of the droop based APC schemes and that the option of sharing the power curtailment among all customers comes at the cost of an overall higher amount of power curtailed.