Sensitivity of Commercial Rooftop Photovoltaic Inverters to Grid Voltage Swell

Abstract

The ever-increasing electricity generation from rooftop photovoltaic (PV) systems, also known as distributed PV (DPV), leads to new challenges for transmission and distribution network service providers. DPV lacks visibility and control from system operators, and this issue becomes critical especially during and after grid contingencies. Technical standards applicable to DPV inverters define expected performance and behavior, however they do not always provide clear guidelines under several grid disturbance conditions. On the one hand, inverters are allowed to respond flexibly. However, knowledge of inverters behavior under grid voltage disturbances is necessary to design and tune the parameters of composite load models, used by power system operators in planning the required power reserve. This article investigates through experiments the sensitivity and behavior of 25 off-the-shelf residential DPV inverters under grid voltage swells. Inverters are found to behave in either of these ways: 1) Ride-through, 2) curtail power, and 3) disconnect. Power curtailment or disconnection under such disturbances can have a detrimental impact on power system security. Accordingly, power system operators should schedule enough power reserves or take other appropriate measures.