Coupling performance analysis of a solar aided coal-fired power plant

Coal-fired power plants are the dominant form for power generation in many countries, even though they are the main contributor to the current environmental crises. The solar aided coal-fired power plant is an attractive new way to reduce the coal consumption by using solar energy. From the perspective of operational mechanism and coupling property, an all-condition mechanism model of the solar aided coal-fired power plant is proposed in this paper. The operation of an N600-24.2/566/566 supercritical coal-fired power plant hybridized with parabolic trough solar collectors is simulated using Matlab/Simulink in the fuel saving mode. And a new evaluation index of solar energy is proposed to reasonably assess solar energy contribution to the solar aided coal-fired power plant. When the solar steam is used to replace the extraction steam in the feedwater heating system, the change of the main steam, the reheat steam, and the extraction steam are discussed as the coupling property is taken into account. Furthermore, thermal economic analysis is carried out to optimize the solar steam replacement and the entrance of inlet feedwater to the solar field. Moreover, the efficiency and output power of the high pressure cylinder, the intermediate pressure cylinder, and the low pressure cylinder are discussed when the extraction steam is replaced by the solar steam in the feedwater heating system. Finally, the output power shock of the solar aided coal-fired power plant caused by the fluctuation of Direct Normal Irradiance is assessed. It is found that the strong fluctuation of Direct Normal Irradiance affects the power quality of the solar aided coal-fired power plant significantly.