Smart Transformer-based Frequency Support in Variable Inertia Conditions

Power electronics-based sources, such as photovoltaic or wind power plants, have been increasingly connected to the power system, changing the share of power production with respect to synchronous generators. These sources do not offer any rotational inertia and thus do not contribute to sustain the system frequency during energy imbalances. As consequence, larger frequency variations are more likely to occur. In this paper, a Smart Transformer (ST) based real time frequency regulation (RTFR) strategy has been proposed. The ST, a power electronics based transformer, can shape the LV grid load consumption, identifying the load sensitivity to voltage by means of On Line Load sensitivity Identification (OLLI) algorithm and then adapting the LV grid voltage to achieve the desired power variation to support the power system frequency. The proposed method is analyzed in a wide range of inertia conditions to highlight the benefit of ST-based RTFR in low inertia condition.