Thermodynamic analysis of combined energy storage systems for enhancing load ramp flexibility in a coal-fired power plant

Optimizing the coal-fired power plant flexibility is crucial for stable power output during fluctuations in renewable energy generation, especially for the low-carbon power system with high solar and wind power proportion in the future. This study proposes an integrated energy storage system combining pulverized coal storage and thermal energy storage to enhance fuel supply management and load response rates. Delay times identified through cross-correlation analysis of operational data are incorporated into simulation models, and exergy analysis evaluates the system's thermal performance. The results show that the proposed system enhances dynamic thermal performance, reducing the time to transition from 20 % to 100 % rated load to 17 min, with an average power change rate of 4.44 % Pe·min−1. The integration stabilizes coal consumption during load ramp-up process compared to the conventional system, with a minimum average coal consumption of 494.63 g·kWh−1. Economic analysis indicates that Strategy A achieves a positive net present value in 5 years, making it suitable for small-scale plants. Strategy C achieves a maximum net present value of $1.73 million over 30 years, favoring large-scale projects. This study provides a reference for designing flexible coal-fired power plant configurations to improve operational efficiency and adaptability.