An improved coordinated control technology for coal-fired boiler-turbine plant based on flexible steam extraction system

Coordinated control system (CCS) used in thermal power unit can quickly coordinate energy balance between the plant boiler and steam turbine, and follow the load commands. The development of renewable energy, however, has increased the load change rate and amplitude requirements for thermal power units. This implies that the difficulties associated with ensuring plant parameters stable and rapid tracking of load commands has augmented as well. In order to improve the peaking rate and amplitude of thermal power units, based on energy and mass balance principles, a dynamic mathematical model of a thermal power unit including steam turbine regenerative systems is developed. The developed model is verified by comparing the results obtained from the model with the corresponding ones coming from field tests. Moreover, an improved coordinated control technology based on flexible steam extraction system is proposed, the flexible steam extraction system is achieved by installing throttle valve in the steam turbine extraction line. Finally, load command step and ramp up simulation tests are carried out under the improved CCS.