Optimization of Active Power Losses for High-Voltage Distribution Grids Using Mixed-Integer Quadratic Programming

The energy transition is leading to increased loading of high-voltage distribution grids (HVDGs), which in turn results in higher active power losses. In addition, the meshed network structure typical for German 110 kV grids enables transit power flows originating from the superimposed transmission grid (TG). These transit power flows may further increase grid loading and active power losses. This paper presents a sensitivity-based mixed-integer quadratic programming (MIQP) approach for active power loss minimization in meshed HVDGs. The proposed methodology achieves near-real-time computation times while maintaining high accuracy by means of a piecewise linearized alternating current (AC) formulation. In addition, losses of static synchronous compensators (STATCOMs) and transformer-reactance variations are explicitly modeled. Reactive power provision by distributed energy resources (DERs) and STATCOMs, as well as discrete tap positions of power transformers (PTs) and phase-shifting transformers (PSTs), are considered as control variables. The proposed approach is validated using hourly snapshots of a real German HVDG provided by a distribution system operator (DSO). The results demonstrate a significant reduction in active power losses together with computation times suitable for near-real-time applications.