Coupled Trading in the Electricity–Carbon–Certificate Market Under the Carbon Tax Mechanism: Evidence from China

The sustainable transition of power systems is currently hindered by fragmented carbon pricing systems and insufficient cross-market synergies. Considering this, we herein construct a system dynamics model of carbon tax regulation under conditions integrating electricity markets, carbon emission trading (CET) markets, and tradable green certificate (TGC) markets using Vensim PLE 7.3.5 software. We also propose a price-matching mechanism and implementation pathway for carbon taxation and CET to advance low-carbon sustainable development. The simulation results show that the introduction of a carbon tax at an initial rate of 50 CNY per ton significantly improves renewable energy investment returns. Moreover, effective coordination between the carbon tax and CET reduces carbon emissions from the power system, delivering benefits in terms of both environmental and socio-economic sustainability. We further identify a dynamic coordination scheme consisting of a carbon tax with an initial rate of 50 CNY per ton, which is appropriate when the CET prices stabilize at approximately 60 CNY per ton. An initial rate of 30 CNY per ton is more suitable when the CET prices rise above 100 CNY per ton. These findings verify the optimal matching rules for carbon tax intensity under different carbon allowance price levels, and they also provide quantitative policy tools and empirical support for the scenario-based regulation of carbon pricing systems to achieve sustainable energy transition goals.