Flow Characteristics Analysis Of Steam Turbine’s Regulating Valves Based On Data Mining

With the implementation of the policy of "developing large units and suppressing small ones" and the strategy of "ultra-low emission",large capacity,high parameters,low consumption and low emission are the main direction for the future development of thermal power units,bringing new opportunities and challenges to the power production process.After long-term operation,DEH or flow path retrofit,the actual flow characteristics of steam turbine’s regulating valves will deviate from the design values,thus affecting the unit primary frequency and load control ability.In order to ensure the safe and stable operation of the unit,the flow characteristics parameters of steam turbine’s regulating valves in the DEH control system of the unit should be matched with the functions of AGC and primary frequency regulation.Accurate acquisition of the actual flow characteristics of steam turbine’s regulating valves is the prerequisite for accurate control.In view of the large data volume and strong coupling of unit operation datas,in this paper,the data preprocessing algorithm is firstly introduced to obtain a compact steady state database.Then,the flow characteristics identification methods of steam turbine’s regulating valves based on experimental data and historical data mining are proposed.The latter includes regression analysis,iterative calculation and variable condition calculation.The improved K-means clustering algorithm is used to refine and fit the results.The DEH valve management curve is optimized and corrected by simulation and piecewise linearization to determine the reasonable overlap of the valves.Finally,the simulation and optimization methods of flow characteristics of regulating valves are introduced,including the throttling losses analysis after the adjustment of overlap.The software is compiled to realize the above functions and applied to a 660 MW unit.The results show that different methods can identify the actual flow characteristics curve of steam turbine’s regulating valves,and verify the correctness and feasibility of the three identification methods.At the same time,the linearity of flow characteristics curve has been greatly improved in sequence valve operation mode,and the capacity of AGC load variation and primary frequency regulation has been enhanced,which provides reference for guiding the actual operation optimization of units.