Impact of fault ride-through and dynamic reactive power support of photovoltaic systems on short-term voltage stability

This paper investigates the impact of the Fault Ride-Through (FRT) capability and the dynamic reactive power support of large-scale PhotoVoltaic (PV) systems according to the newly proposed German Grid Code (GGC) on short-term voltage stability. The PV system is based on a generic model and realistic parameters are used that are determined in consultation with a manufacturer. In this context, improvements of the generic PV system model are stated. The GGC requirements are compared with several other control schemes for dynamic reactive power support, such as the adjusted control mode, i.e., the active and reactive current is calculated according to the grid impedance angle. The results show that the GGC requirements help the power system to avoid short-term voltage instability. Moreover, the requirements lead to an enhanced dynamic performance in terms of voltage support and recovery. Only the adjusted control mode shows a slightly better performance than the GGC. However, as this control scheme needs on-line information about the grid impedance angle, and therefore, additional infrastructure for the measurements, it is also more expensive. Hence, it can be concluded that the GGC requirements, with respect to FRT and dynamic reactive power support, are reasonable from a technical and economical point of view.