Practice and Power Constraint Analysis of Dynamic Low-Voltage Mitigation in Rural Distribution Networks Using Terminal User-Side Energy Storage in Transformer Areas

To address the prevalent time-segmented terminal low-voltage issue in rural distribution transformer areas of the hilly northeastern Sichuan region, a dynamic mitigation field trial was conducted by installing user-side energy storage devices at the terminal end of the A-transformer area serving Gaolongshan Village on the 10 kV Guangwen Line, under the jurisdiction of Yilong Yongle Power Supply Station in Nanchong. The causes of low voltage, the system architecture of the mitigation device, and its closed-loop control strategy—prioritizing reactive power over active power—were presented, along with voltage comparisons before and after commissioning. Field data indicate that the 7 kW-rated energy storage device raised the minimum terminal voltage from 178 V to 223 V, and the monthly voltage qualification rate increased from 82.50% to 99.09%, demonstrating marked improvement. However, during evening peak-load periods, the device′s rated power limit left some terminal voltages still below the 198 V lower threshold, indicating limited mitigation effectiveness. A mechanistic analysis based on the line voltage-drop equation revealed that the root cause of this limitation lies in the insufficient active and reactive power output capacity of the storage device. Improvement measures—including power capacity augmentation, multi-point distributed deployment, and coordination with reactive power compensation—were proposed, offering practical references for low-voltage mitigation in similar rural distribution networks.