Research On The Load Response Of Thermal Power Units Caused By Condensate Throttling

When large units (supercritical units and ultra supercritical units) runs, they are usually under sliding pressure operation, and the steam turbine control valve will full open to ensure the economy of the unit. This situation will make the heat storage of boiler become smaller and smaller, which will not up to higher demand for frequence-modulated of the power grid. Condensate throttling comes into being in such a background.Condensate throttling is a way that can change load of unit quickly, by changing the flow of steam in the turbine to regenerative system in a short time, the work the steam did in the turbine will change. This way can not only to meet the frequence-modulated of the power grid and improve the level of AGC(Automatic Generation Control), but also to improve the economy of the unit.To master the influence of condensate throttling to unit load and other parameters By means of theoretical analysis and modern test,which is the basis of load optimization control of realizing condensate throttling, and also is the basis of improving the response rate of AGC.Based on the steam-water distribution general matrix equation of thermal dynamic system, the relationship between the variation of unit loadand the variation of the condensate water is discussed, then the functional relationship between the two variables is established, at last we reach the goal of attaining the needed condensate water flow according to the load demand. Based on 600 MW unit thermal equilibrium figure of Datang Panshan Power Plant, the maximum amount of power adjustment of each condition is calculated, and then the functional relationship above is analyzed and verified. The result shows that in the confirmed condition, we can achieve the goal of attaining the needed condensate water flow according to the load demand with the obtained functional relationship, at the same time, we also know in the different conditions, the larger the load of the unit is, the better effect which is obtained by the way of condensate throttling will be.Finally, this paper also combines the 1000MW unit condensate throttling test results of Pinghai power plant, the cause of the difference between the theoretical calculation and experimental result is analyzed.