Short-term voltage stability improvement by active and reactive power control using advanced fault ride-through capability of photovoltaic systems

The large integration of photovoltaic (PV) power generation systems into power systems causes deterioration in power system stability. In our previous work, we have shown that reactive power control using the inverters of PV systems, known as the dynamic voltage support (DVS) capability, is a promising approach to improve the short-term voltage stability. In this paper, we propose a novel DVS capability as a function in the advanced fault ride-through (FRT) capability of PV inverters. In contrast to the conventional DVS capability, the proposed method uses both active- and reactive-power injection to improve the short-term voltage stability. Numerical examples show that the proposed DVS capability further improves the short-term voltage stability compared with the conventional DVS capability. Further, the proposed method can alleviate a frequency drop after a fault caused by interruption of the PV systems.