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This paper investigates the impact of: i) the Low Voltage Ride-Through (LVRT) and Dynamic Voltage Support (DVS) capability; ii) the active current recovery rate; iii) the local voltage control; and iv) the plant-level voltage control of large-scale PhotoVoltaic (PV) systems on Short-Term (ST) voltage stability and Fault-Induced Delayed Voltage Recovery (FIDVR). Moreover, the influence on transient and frequency stability is studied briefly. To evaluate FIDVR, a novel metric, the socalled Voltage Recovery Index (VRI), is defined. The studies are performed with the WECC generic PV system model on an IEEE voltage stability test system, namely the Nordic test system. The results show that without LVRT capability the system is ST voltage and transient unstable. Only the LVRT and DVS capability help to avoid ST voltage and transient instability.Considering voltage and frequency dynamics, an active current recovery rate of 100 %/s shows the best performance. To further enhance voltage dynamics, plant-level voltage control together with local coordinated reactive power/voltage control should be applied. Moreover, the VRI provides useful information about the FIDVR and helps to compare different ST voltage controls.Index Terms-Fault-induced delayed voltage recovery, dynamic reactive power support, dynamic grid support, fault ridethrough, induction motors, large-scale photovoltaic plants. I. INTRODUCTIONA. Motivation T HE electrical power system has undergone fundamental changes due to the increasing penetration of inverter based generation, i.e., wind and PhotoVoltaic (PV) generation. The dynamic characteristics of these technologies are different from conventional synchronous generators, which may impact the performance of the power system.

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Abstract-Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large synchronous generators as the dominating generation technology. Up to now, transient stability of transmission systems has been analysed to a satisfactory degree of accuracy with a simplified representation of the distribution systems. In future, distributed generation will more and more influence the behaviour of the system. Stiff, inverter-based local generation technologies may improve the system stability; however, increasing electrical distances between large synchronous generators in operation will impede the system stability. These (and other) diverging effects have to be studied in detail. This overview paper summarises the latest findings and reveals future research questions. It is concluded that the accuracy and validity of the currently applied dynamic models for transient stability analysis of power systems with high penetration of DG should be further investigated.

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