| In recent years,the task of power units participating in peak load regulation is more and more important,and the "two rules" of the power grid are more and more strict for the quality of power control.As the main executive mechanism of the DEH system,the flow characteristic of the turbine is the function of the steam flow instruction and the opening degree in the DEH system when the unit is working.The output of the steam turbine is the function of the steam flow and the power of steam in the steam turbine.There is a complex nonlinear relationship between the steam flow of the steam turbine and the opening of the valve.Consistent g overning valve management function and the actual characteristics,is the basis of good control performance of steam turbine.In this paper,the basic control function of DEH and the power control model of the unit are studied.On this basis,the influence of the governing valve flow characteristics on the speed control and power control of the unit is analyzed in detail.The test method is used to optimize the DEH valve management function,so that the flow specificity of the governing valve of the turbine is consistent with the actual characteristics,and the precision control of the speed and power of the unit is realized.In view of the problem of the valve dithering in the operation of Fanping 2 unit and the poor quality of AGC and primary frequency mod ulation in operation,this paper studies an optimization method for the flow characteristics of the governing valve.Firstly,through the test of flow characteristics,the mathematical models of flow instructions,gate opening and actual flow are establish ed.Based on this model,the relevant data of the unit under the thermodynamic stable condition are obtained,and the actual flow characteristics curve is fitted.The mathematical model of the unit flow characteristics is established.On the basis of the a ctual operation characteristic of the unit,the valve function is adjusted and optimized repeatedly until the total flow command corresponds to the line shape of the actual flow regulation.After the optimization of the flow characteristics of the valve,the problem of the jitter in the overlap area is solved.The adjustment process is continuous and smooth.The linear relationship between the actual flow and flow instruction has a good linear relationship.It can accurately correspond and overcome the dead zone in the original flow characteristic curve.The load response rate of the AGC section is about 15 seconds,and the optimization effect is obvious.The optimization of the flow characteristics of governing valve is based on the actual flow characteristics of the unit,and the mathematical model is established and optimized.The optimization method has universal applicability. |
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