Enhancing the load cycling rate of subcritical coal-fired power plants: A novel control strategy based on data-driven feedwater active regulation

To accommodate high penetration of renewable power, coal-fired power plants should have high operational flexibility. However, the load cycling rate of subcritical power plants is insufficient, because conventional control strategies cannot perform well when subcritical power plants that have large thermal inertia change load with high rates. To address this issue, a novel control strategy based on idea of data-driven feedwater active regulation was proposed. To evaluate the control performance, dynamic modeling on a reference 330 MW subcritical unit was conducted, and performance indicators including load cycling performance indicator K_p, parameters cumulative deviation, and transient process average coal consumption rate were defined. Results reveal that key factor restricting load cycling rate is the exceeding of key parameters deviations. During 50%–75 % loading up process, the novel control strategy can increase ramp rate by 1.0 % Pe/min, increase K_p by 101.7 %, and reduce parameters cumulative deviations by 58.0 % at maximum and 20.3 % on average. Meanwhile, during 75%–50 % loading down process, the novel control strategy can increase ramp rate by 1.0 % Pe/min, increase K_p by 39.9 %, and reduce parameters cumulative deviations by 32.0 % at maximum and 19.1 % on average. These results demonstrate that feedwater active regulation effectively suppresses the control deviation of key parameters.