Control of Distribution Voltages Considering Voltage-Dependent Flexibility Regions

The increasing penetration of renewable generation at the distribution level creates voltage-related challenges for grid operators. In the future, the need for voltage control in active distribution networks will increase while at the same time the number of heterogeneous assets operating flexibly in terms of active and reactive power also increases, rendering the operation of distribution networks more challenging. In this paper, a novel Model Predictive Control (MPC)-based voltage controller is proposed that leverages the control capabilities and Flexibility Operating Regions (FXORs) of active distribution networks to help keep distribution voltages within predefined limits. Specifically, the concept of voltage-dependent FXORs is introduced to account for the availability of manipulated resources participating in the voltage regulation in a realistic set-up. Numerical simulations on a CIGRE medium voltage distribution network validate the performance of the controller in regulating voltages using flexible resources with variable power inputs and outputs.