一种基于主汽压预测的火电机组负荷控制方法

A load control method of thermal power unit based on predictive main steam pressure

针对火电机组因锅炉大惯性导致负荷响应慢、汽压波动大等问题,提出一种基于主汽压预测的火电机组负荷控制方法。该方法以锅炉跟随控制方式为基础,根据预测模型,由负荷指令和当前燃烧率预测出主汽压变化趋势,根据预测主汽压与当前主汽压偏差来修正锅炉侧的能量需求,以超前改变入炉能量,提高机组的负荷响应速率,减少主汽压波动。以某1 000 MW超超临界机组为例,建立其压力预测模型并进行负荷控制阶跃仿真实验,结果表明:采用该方法使得燃料量控制兼顾快速性和准确性,能有效改善机炉之间协调特性,使机组负荷响应快、超调量小,同时主汽压波动小。

As boiler inertia characteristics lead the thermal power unit to have slow load response speedand large steam pressure fluctuation, a load control strategy based on predictive main steam pressure was proposed to solve those prob- lems. The strategy was based on boiler followingcontrol mode. According to the main steam pressure prediction model, the change trend of main steam pressure was predicted by load instruction and current fuel quantity, and the energy de- mand of boiler was then corrected by the deviation between the predicted and actual value of main steam pressure. The import energy of boiler was controlled in advance, by which the unit load response rate was improved and the main steam pressure fluctuation was reduced. The main steam pressure prediction model of a 1 000 MW ultra-supercritical boiler unit was built and control, simulation tests were made. It was shown that with the new control method the fuel control of the unit had rapidity and accuracy, the coordination characteristics between turbine and boiler was improved, and finally the unit load response became faster with smaller overshoot while the main steam pressure changed with small fluctuation.