基于模型煤发热量软测量的BTU校正方法分析

Model-based soft measurement for coal calorific value and BTU correction method

传统BTU校正方法存在抗扰动能力和稳定性差等问题。对此,将基于模型煤发热量软测量的BTU校正方法与传统BTU校正方法进行了对比分析,并利用某亚临界600 MW机组运行数据对基于模型煤发热量软测量的BTU校正方法进行试验验证。结果表明:利用机组发电负荷-汽轮机前压力简化非线性动态模型计算煤发热量,可消除燃料量和汽轮机调节汽阀开度变化对机组协调控制的影响;通过低通滤波可使BTU校正逻辑的工作频率低于机组协调控制系统的工作频率,从而保证了整个控制系统的稳定性;该校正方法具有良好的动态、静态稳定性及较强的抗干扰能力,计算精度及滞后时间均能够满足要求,可用于负荷频繁变化的火电机组。

The conventional BTU correction logic has disadvantages of low capability of anti-load jamming and poor stability.Against this problem,the conventional BTU correction method and the one for modelbased soft measurement of coal calorific value were analyzed.Moreover,the operation data of a subcritical600 MW unit were used to carry out experimental verification for this BTU correction method for modelbased soft measurement of coal calorific value.The results show that,using the simplified nonlinear dynamic model of unit load-throttle pressure,the calorific value of coal was calculated,which can eliminate the effects of fuel flow variation and opening degree variation of turbine regulation valves on the coordinated control system.By employing the low-pass filter,the operation frequency of the BTU correction logic can be lower than that of the coordinated control system and the close-loop stability of all system can be guaranteed.The practical applications indicate this method has better dynamic and static stability,and the antijamming ability is higher.The calculation precision and lag time can satisfy the local demand and can be suitable for thermal power units with frequently changed generation load.