Performance analysis of a solar-aided coal-fired power plant in off-design working conditions and dynamic process

Solar-aided coal-fired power generation is a promising technique to reduce cost and enhance the efficiency of concentrated solar power. Operation optimization is important but has difficulty improving the performance of solar-aided coal-fired power plants, due to the fluctuations in power load and solar energy. Therefore, the operation performance and dynamic characteristics of a solar-aided coal-fired power plant were investigated in this study. A model of the plant including trough collector system and coal-fired plant was developed. A case was studied to demonstrate the model practicability on basis of a 600 MW supercritical coal-fired plant and a trough collector system integrated in parallel with #2 and #3 high pressure heaters of regenerative system. Under different solar irradiances, operation characteristics were analyzed from 100% to 50% loads with varying ratio of feedwater to trough collector system. The solar-to-electricity efficiency under different off-design conditions was obtained. Moreover, the dynamic response characteristics of solar-aided coal-fired power plant were studied with the disturbances of direct normal irradiance and ratio of feedwater to trough collector system. Results showed that the solar-to-electricity efficiency in design condition was 25.80%. The adjustment of the ratio of feedwater to trough collector system could lead to an optimized operation. Furthermore, the dynamic characteristics of trough collector system and solar-aided coal-fired power plant were analyzed. The results are expected to guide the control optimization of solar-aided coal-fired power plant.