Effect of fuel side deviations on the load-cycling performance of thermal power plants: A dynamic simulation

The operational flexibility of thermal power plants plays a critical role in accommodating the high penetration of intermittent renewable power. The load-cycling rate, which is an important feature of operational flexibility, is insufficient for thermal power plants. The unpredictable fuel side deviations that weaken the control system effect restrict the load-cycling performances of thermal power plants because fuel side parameters, including coal feed rate, air flow rate, and coal quality, cannot be controlled precisely due to the accuracy error of devices and variation in fuel characteristics. To explore the influence of fuel side deviations on the load-cycling processes of thermal power plants, dynamic simulation models of a coal-fired plant are developed, and the load-cycling processes with continuous deviations in the fuel side are simulated. The deviations of output power, live steam pressure, and live steam temperature are calculated and used to evaluate the influences. Results show that coal quality deviation has the most significant effect on load-cycling performance, which makes the maximum and cumulative deviations in output power increase to 1.15 and 1.10 times that without fuel side deviation. The effect of multiple input deviations lies upon the most significant deviation. For example, the maximum and cumulative deviations of output power increase to 1.15 and 1.09 times with deviations in the coal feed rate, air flow rate, and coal quality, which are close to those with only coal quality deviation. Reducing the impact of the dominant factor can effectively enhance the load-cycling performance of the coal-fired unit.