Unbalance Mitigation in an Active Distribution Network Considering Volt-VAr Optimization and Battery Energy Storage

Electric grids equipped with phase-specific controllable elements can increase current and voltage unbalance levels, inducing power quality problems in three-phase active distribution systems. Voltage regulator operations, capacitor bank settings, single-phase inverter power injections, reactive power compensation, and battery energy storage (BES) can all interrupt the symmetry of three-phase currents and voltages. Any attempt to maintain reasonable voltage magnitudes in a three-phase system can create unbalance issues along-side increased tap operations. This paper proposes an optimization formulation with multiple objectives to obtain operational advantages such as minimizing current and voltage unbalance levels, voltage deviations, and switching operations on regulator taps. Technologies such as the voltage regulator operation, PV-BES inverter reactive power dispatch, and BES real-power dispatch are considered in the formulation. A modified IEEE-34 bus system is used for testing and validation. The proposed heuristic-based multi-strategy approach reduces unbalance levels up to 30%, voltage deviation index by 19%, and daily tap operation count by 43%, while ensuring an acceptable voltage profile in varying load conditions.