A combined external delivery optimization model for wind power and thermal power considering carbon trading and tradable green certificates based on Credibility theory

• A wind–thermal power independent external delivery model is proposed.
• A wind–thermal power combined external delivery model is proposed.
• The Credibility theory is introduced to overcome wind power randomness.
• The influence of the carbon trading on wind power consumptive is analyzed.
• The influence of the tradable green certificates on wind power consumptive is analyzed.

To reduce the impact of wind power prediction error on power system operation, Credibility theory and Fuzzy chance constrained programming method are introduced while solving wind power inter-regional scheduling optimization problems. Firstly, the paper introduces the carbon trading (CT) and Tradable Green Certificates (TGC). Then, an energy independent external delivery model is constructed, which contains wind power independent delivery model and thermal power independent delivery model. Secondly, the paper put forward energy combined external delivery model considering CT and TGC. Meanwhile, Credibility theory and Fuzzy chance constrained programming method are used to deduce credibility distribution function of wind power prediction errors and define the feasible region under a certain confidence level, respectively. Since credibility distribution is applied as a measure function and the feasible region covers fuzzy event set, the optimal solution will be in the credible solution space. Thirdly, four scenarios are set according to CT and TGC. Finally, this paper uses six thermal power units and one wind farm as the simulation system. The simulation results show Credibility theory is applicable to overcome wind power uncertainty. Energy combined external delivery is better for improving system consuming wind power. CT and TGC could increase wind power grid-connection, but CT’s optimization effect is more obvious than TGC. The optimization effect reaches the optimum when both CT and TGC are implemented, and energy external delivery profits should be reasonable allocated for encouraging thermal power to participate in wind power delivery.