After long-term operation and retrofit of digital electro-hydraulic (DEH) control system or flow path of steam turbine, the actual flow characteristic curve of the turbine's regulating valve will deviate from the design values, thus affecting the unit's primary frequency and load control ability. However, the field flow characteristics test has common shortcomings of severe test conditions, long duration and low precision. In this article, through analysis and excavation of the unit's historical operation data, two methods are proposed for different situations to identify the actual flow characteristics of the steam turbine's regulating valve. The flow characteristic curves of each valve are obtained by iteration calculation when the downstream pressure data can be achieved, or by the Freugel's formula when the downstream pressure data can not be achieved. The DEH valve management curve is optimized by simulation and piece-wise linearization to determine the reasonable valve overlap degree. The application of this method in a 660 MW unit shows that, in sequence valve operation mode, the linearity of the flow characteristics curve has been improved greatly, and the capability of the load variation and primary frequency regulation have been enhanced.%汽轮机在经过长期运行、汽轮机数字电液控制系统(DEH)或通流部分改造后,汽轮机调节阀的实际流量特性曲线将偏离设计值,从而影响机组一次调频和负荷控制能力,而现场流量特性试验存在试验条件苛刻、耗时长、精度低等缺点.本文通过对机组历史运行数据进行分析和挖掘,针对不同的情况提出2种方法以辨识汽轮机调节阀实际流量特性,有阀后压力数据时采用迭代计算求出各阀门流量特性曲线,无阀后压力数据时采用弗留格尔公式求出阀组流量特性曲线,分别通过仿真和分段线性化对DEH阀门管理曲线进行优化修正,确定阀门合理的重叠度.将该方法应用于某660 MW机组,结果表明在顺序阀模式下,汽轮机调节阀流量特性曲线的线性度有了很大改善,机组自动发电控制(AGC)变负荷和一次调频的能力得到了提高.
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