Impact of Large-Scale Distributed Photovoltaic Integration on Voltage and Line Loss in Distribution Networks

With the advancement of the “dual carbon” strategy and the construction of a new-type power system, the penetration of distributed photovoltaic (PV) systems in China’s medium-and low-voltage distribution networks has been continuously increasing. Their large-scale integration has a significant impact on voltage distribution and line losses. To analyze the influence of PV installation location and capacity on the operational characteristics of distribution networks, this paper establishes a mathematical model of voltage and line loss based on a radial distribution network. The effects of grid-connected capacity, node impedance, and power flow direction on system voltage and line loss are theoretically examined. The results show that distributed PV, within a certain capacity range, can reduce line losses and improve voltage quality. However, when the grid-connected capacity exceeds a critical threshold, voltage limit violations and increased reverse power flows occur, leading to higher line losses and operational risks. A grid-connection principle is proposed, suggesting that “small-capacity PV units should be installed near the load side, while large-capacity units should be located closer to the bus side.” This study provides a quantitative basis for the planning and operational control of distributed PV integration and offers theoretical and technical support for optimal distribution network operation.