To investigate the evolution path of the urban power system supply structure, analysis is conducted on the factors influencing the installed capacity of various power source types in the urban power system, a system dynamics model for the urban power system supply structure evolution is established. The model includes modules for power balance, thermal power development, distributed photovoltaic development, centralized wind and photovoltaic development, and new energy carrying capacity. In the modeling process, the symbolic regression method is used to objectively and accurately set the model parameters, with a focus on the impact of low-carbon policies on various types of power sources, as well as the feedback effect of renewable energy carrying capacity on the installed capacity of renewable energy. Through differentiated simulations under low-carbon policy scenarios, the changing trends of various types of power capacity, the proportion of new energy access, and the new energy carrying capacity in future urban power systems are obtained. Simulation results indicate that low-carbon policies contribute to the development of new energy and the achievement of "dual-carbon" goals, promoting the green and low-carbon transformation of urban energy systems. However, excessive policy intensity may lead to insufficient renewable energy carrying capacity in urban power systems, causing issues in the absorption of new energy.