Scenario-based Smart Transformer Implementation for Reactive Power Management in MV and LV Grid

The increasing amount of distributed generation and new load structures lead to technical challenges for the future electric grid. An implementation of a Smart Transformer (ST) could solve grid stability issues through grid services such as reactive power injection in order to guarantee a predefined voltage profile for grid assets. In this paper, three consecutive use-cases dealing with voltage limit violations are tested in a medium voltage (MV) grid in status quo and forecasted scenarios of the years 2030 and 2050, respectively. A quasi-stationary simulation is carried out to determine the positioning of a Smart Transformer for optimal voltage support. Furthermore, the influence of load controllability in low voltage (LV) grid to enhance the ST’s service capability is investigated. LV grid voltage-sensitive load controllability is beneficial as its implementation leads to a lower demand of Smart Transformers in MV grid. In a third use-case, a comparison between LV grid control schemes is performed in order to find beneficial conditions for ST implementation in MV and LV grid. Results indicate that flexible power classes of the ST maximize its usage for voltage regulation. A trade-off between LV control schemes can be seen with respect to both voltage levels, which has to be taken into account when choosing an appropriate control scheme.