In China's power supply system, the distribution network is an important component, and the medium and low voltage distribution network is a terminal device directly connected to users. How to reduce unnecessary energy losses in regional distribution networks to achieve regional energy conservation and carbon reduction has important technical and economic significance. However, currently, there are certain operational problems in the existing medium and low voltage distribution networks, with the most prominent being high energy consumption. Therefore, this article estimates the energy-saving effect of distribution networks through protective voltage reduction methods supported by smart grids. To achieve higher energy-saving effects, this article maintains the node voltage within an acceptable range and combines it with the photovoltaic system for deeper voltage reduction. The simulation results show that the system performance in this paper is the most stable, with a voltage amplitude of 0.87, and it has been proven through practical applications that the energy consumption of this system is the lowest, with an average energy consumption of 3595.375kWh per hour. This system can achieve higher energy savings and reduced peak load demand.