亚临界燃煤机组高加抽汽调节建模与动态模拟OA

[Objective]To address the insufficient frequency regulation speed of subcritical coal-fired power units under high renewable energy penetration,a high-pressure heater extraction steam regulation strategy is proposed to enhance the unit's load response flexibility.[Methods]A fully coupled dynamic model of the boiler-turbine-regenerative system is developed using Modelica and validated against design data under 75%THA and 50%THA operating conditions.On this basis,dynamic simulations are conducted at 75%THA to evaluate the effects of different HP-heater extraction-steam cut-off schemes on load response,feedwater temperature,heat-rate variation,and regenerative-system operating parameters.Furthermore,a"preset-feedback"combined control strategy for HP-heater extraction regulation is designed.[Results]Under the 75%THA condition,cutting off extraction steam of the No.0 HP heater enables a 4.5%relative load rise within 160 s,with a response speed three times that of the No.1 HP heater.Meanwhile,the unit heat rate increases from 7 842.81 kJ/(kW·h)⁻¹ to 7 848.63 kJ/(kW·h)⁻¹,corresponding to a marginal rise of only 0.0742%.With the proposed combined control strategy,the heat-rate increase is further reduced to 0.0315%,and the extraction-steam change of the No.0 HP heater decreases from-8.47 kg/s to-7.01 kg/s,indicating significantly weakened extraction disturbances.In addition,the deaerator level,condenser level,and main-steam temperature remain within safe operating limits.[Conclusion]The extraction regulation of high-pressure heater can significantly improve the load response speed and regulation flexibility of the unit while ensuring thermal economy and operation safety.The proposed combined regulation strategy effectively improves the energy utilization and dynamic stability of the system,and provides a method reference for the engineering application of high-pressure heater extraction steam regulation in the flexibility improvement of coal-fired units.