Abstract: The cogeneration unit is equipped with an electric boiler for thermal electro-coupling to promote the integration of new energy such as wind power. To determine the optimal capacity configuration of the medium-electric boiler in the thermal power plant, the concept of the feature day is introduced, and the constraints during the boiler operation are elaborated in this paper. Then a mathematical model is established by setting peaking increment and economic net present value of the unit as the objective functions respectively. The results show that for the 330 MW unit, when the heating supply of the electric boiler reaches 52 MW, the maximum peak-increasing increment can be obtained if the investment cost is not considered. The electric heating power of the electric boiler is 178.28 MW by then. While in the case of the investment cost taken into account, with the heating power of the electric boiler reaching 49 MW, the electric heating power of the electric boiler is 168 MW and the maximum economic net present value is achieved.

Key words: CHP unit, wind and heat conflict, electric boiler, peak load increment, economic net present value, optimal capacity