Impact of inverter-based distributed generation with voltage-dependent control on long-term voltage stability

This paper investigates long-term voltage stability during disturbances, considering interactions between transmission and distribution systems in the context of inverter-based distributed generation (IBDG) with voltage-dependent control. Such research is crucial for future coordination of voltage control in distribution and transmission systems and for securing long-term voltage stability. To reduce complexity, a methodology for model reduction of distribution systems with voltage-dependent control of IBDG is proposed. Such a reduction method, utilizing REI (Radial, Equivalent, Independent) grid reduction technique, may be a key for adequate representation of distributed generation and its influence on the voltage stability in the future. The validity of the method is confirmed by time domain long-term voltage simulations using detailed and reduced models. In the subsequent investigation, publicly available grid models of distribution and transmission systems are used, and the proposed reduction method is applied to distribution systems. Varying the share of IBDG with voltage-dependent control and the number of conventional power plants in the transmission system, a time-domain simulation is used to apply disturbances. The voltages in the transmission and distribution system and the influence of IBDG are observed, concluding with a discussion on the influence of distribution systems with numerous IBDG on long-term voltage stability.