Co-operative dynamic export limits for unbalanced low-voltage networks

The accelerated growth of distributed energy resources (DERs) is pushing low-voltage (LV) distribution networks towards their hosting capacity limits, leading to voltage violations, transformer overloading, and increased photovoltaic (PV) curtailment. Dynamic export limits (DELs) can improve network utilization compared with static export limits. However, centralized DEL schemes can be difficult to scale, require detailed prosumer data, and introduce communication and single-point-failure risks. This paper proposes a co-operative two-layer prosumer control architecture for unbalanced three-phase four-wire LV networks, where the distribution network operator (DNO) provides network information and operating limits, while prosumer-side controllers compute feasible DELs using anonymized real-time measurement exchange. The calculated DELs are then used by local home energy management systems (HEMS) to optimize PV, battery energy storage, and electric vehicle charging. Two DEL allocation strategies are developed: equal addition/reduction and phase-wise proportional curtailment. Base-case simulations on an unbalanced 49-prosumer LV network show that the phase-wise proportional curtailment method reduces total curtailment by 13.5%, compared with the equal addition/reduction method, while maintaining a Jain’s fairness index of 0.9663. Model validation against power flow results shows a maximum voltage estimation error of 1.31 V in the base-case and below 1.98 V under severe phase unbalance conditions. The HEMS-integrated framework increases the mean daily net financial return of prosumers by 33.7%, and decreases network-wide PV curtailment by 39.4% compared with day-ahead DEL scheduling. Case studies on multiple LV networks show that the proposed framework maintains all customer voltages and transformer loading within their operational limits.