Fairness and Voltage Quality Enhancement through Active-Reactive Dynamic Operating Envelopes in Unbalanced Low-Voltage Networks

This paper presents a novel fairness-aware dynamic operating envelope (DOE) framework for equitable active and reactive power allocations in unbalanced low-voltage (LV) networks with high penetration of distributed energy resources (DERs). The proposed method extends proportional fairness from conventional active power definitions to apparent power, allowing customers constrained in active export to contribute via reactive power support. A multi-phase current–voltage optimal power flow (OPF) formulation is developed, incorporating inverter capability constraints, transformer loading limits, and voltage unbalance factor (VUF) mitigation. The VUF is explicitly regularised to address phase-level voltage quality issues arising from asymmetric DER installations and single-phase connections. Time-series simulations on a real-world Australian LV feeder demonstrate that the proposed Fair(P,Q)DOE with explicit VUF regularisation consistently maintains transformer and voltage constraints, reduces VUF below industry guidelines, and improves both fairness and network utilisation compared to existing methods. Results confirm that integrating reactive power flexibility and unbalance-aware fairness metrics enables a more inclusive and power-quality-compliant operation of DER-rich LV networks.