Low-carbon power system paves a way to fully utilize the renewable energy resources. However, it is confronted with new challenges due to the stochastic and uncertain nature of renewable energy resources. To address these challenges and evaluating the accommodation capability of renewable energy in spot markets, a two-stage stochastic unit commitment model is set up by choosing representative scenarios with the consideration of deep peak regulation. In this paper, the deep peak regulation is strictly modeled as a convex representation, which is served as a kind of flexible resources to cope with the stochastic renewable energy output. Simulation results have verified the effectiveness of the proposed model.