From support to marketization: Electricity–Carbon–Green certificate market coordination reshaping new electricity system under dual price-difference settlement mechanism

Under the concurrent implementation of multiple low carbon policies, interactions among the electricity market, carbon market, and green certificate market may generate policy overlap, incentive misalignment, and distorted price signals, thereby affecting the market integration of renewable energy. To examine how coordinated reforms across multiple markets shape this process, this study develops an integrated SD-ABM framework incorporating daily spot clearing, monthly contract for difference settlement under the mechanism price, and annual investment updating. The model is used to characterize market participants’ dynamic decisions and system evolution under alternative policy scenarios. The results show that: (1) The mechanism price plays a necessary stabilizing role during the early stage of renewable market integration, but its function is essentially transitional in nature; the simulation identifies an endogenous inflection point in 2032, after which the mechanism price departs from its baseline level and enters a sustained downward trajectory, signaling a shift in policy focus from revenue protection to accelerated market-based competition; (2) Compared with conventional static price floor arrangements, a feedback-based adjustment mechanism that is dynamically adjusted on the basis of compliance performance, relative profitability, and compensation cost pressure achieves a better balance among revenue stability, cost control, and the transition toward marketization; (3) Effective policy instruments differ markedly across institutional stages: during the 2025-2031 transitional support stage, the DPDSM continues to serve as the primary support for the marketization of the power sector; in the phase-out stage, coordination across the electricity, carbon, and green certificate markets becomes more critical, gradually giving rise to a policy mix characterized by “the carbon-market constraint as the dominant force, the green certificate incentive as a complement, and an orderly exit of the mechanism price.' (4) Composite Scenario 4 outperforms both the baseline and all single-policy scenarios: its realized RPS attainment in 2035 reaches approximately 0.40 and the widening of the TE and RE installed capacity and unit profit gaps is the most pronounced, confirming that multi-market coupling outperforms the strengthening of any single instrument. Overall, the market integration of renewable energy does not rely on the prolonged continuation of any single support instrument; rather, it depends on the orderly re-coordination of market stability, carbon constraint, and green value compensation across different institutional stages.