Abstract: As the cost for wind power and photovoltaic power generation continues to decline, the economic conditions are gradually becoming feasible for wind power and photovoltaic power to replace thermal power. At the same time, as the scale for wind power and photovoltaic power to replace the thermal power increases, the power system needs to introduce energy storage to cope with the increasing net load fluctuations of the power system. In order to quantify and evaluate the economy and scale for renewable energy with energy storage to replace thermal power in a more scientific way, this paper firstly established a joint power generation and energy storage optimization planning model based on the operation simulation of refined time series curves with consideration of the flexibility requirements of the power system. By taking the lowest total system cost as the optimization goal and considering the investment decision-making constraints and operation constraints, the proposed model can coordinate and optimize the capacities of power generation and energy storage under different cost scenarios. The economic analysis process for renewable energy with energy storage to replace thermal power is proposed. Secondly, the proposed model and method were used to optimize the power generation and energy storage capacities for a regional power grid under three scenarios of high-, medium-, and low-cost, and the evolution process for renewable energy with energy storage to replace the thermal power under different cost scenarios was quantitatively analyzed. Finally, the conditions for renewable energy with energy storage to replace thermal power in varying degrees are proposed.

Key words: renewable energy, energy storage, replacing thermal power, time series operation simulation, planning model