基于DCS系统变频循环水泵节能自动控制

第46卷第12期中国电力Vol. 46, No. 122013年12月ELECTRIC POWERDec.2013发电基于DCS系统变频循环水泵节能自动控制张利,张宇,刘卫平,甘智勇,王建(天津市电力公司电力科学研究院,天津300384)摘要:以运行机组DCS系统为基础，介绍了一种变频循环水泵节能自动控制的实现方法。从节能自动控制的理论和原理出发.通过实时计算凝汽器的运行清洁系数，采用循环重复计算法求取凝汽器最佳真空及对应的变频循环水泵运行方式,对比分析并确定节能自动控制的实现方案，详细阐述了建立节能自动控制系统的注意事项以及实现过程中遇到的问题及解决方法，以某电厂330 MW热电联产机组为例进行了测算，实施变频循环水泵节能自动控制后年可节电376.16万kW.h。关键词:火力发电厂: DCS系统;变频循环水泵;节能自动控制系统中图分类号: TK264.1文献标志码: B文章编号: 1004-9649(2013)12-0059-030引言式中:Q为冷却水流量，kg/s;cp为冷却水平均温度下的比热容，J/(kg-K); tr 为冷却水出水温循环水系统是火力发电机组重要的热力系统度，c; 1为冷却水进水温度，C; A为凝汽器有之一，循环水泵是电厂最主要的辅机耗电大户,效换热面积，m;LMTD为凝汽器对数平均温提高循环水系统的运行经济性长期以来是广大节差, C; K。为基本传热系数，W/(m2.9C); B,为冷能工作者研究的主要方向之- 1141。 近年来，随着却水进水温度修正系数; B.为冷却管管材和壁厚变频调速技术的发展，变频调速的可靠性不断加修正系数。强，初期投资成本不断降低，使得高压变频调速1.2 最佳真空及循环水泵运行方式的计算技术在火电厂循环水泵上的应用越来越广泛5，循采用循环重复计算法求取凝汽器最佳真空及环水泵将逐步进入变频时代。对应的循环水泵运行方式，具体计算流程如下:变频循环水泵可以实现循环水泵转速和循环①假设循环水泵变频器输出反馈信号x，计算该水流量的连续性调节，从而实现凝汽器最佳真空变频转速下循环水泵耗功w。和循环水流量Q。的精确控制，同时为循环水泵的节能自动控制提②结合运行清洁系数计算过程中得到的当前运行供了前提和基础。因此，优化变频循环水泵运行工况下凝汽器热负荷和运行清洁系数B.依次计算控制方式，建立变频循环水泵节能自动控制系统，循环水温升Ot、凝汽器端差δ和蒸汽凝结温度t。o充分挖掘变频循环水泵的节能潜力，将成为未来③由蒸汽凝结温度I,计算假设循环水泵变频器输循环水系统节能工作的重点和发展方向。出反馈时凝汽器压力p.,得到该真空状态下对汽轮机功率的影响△W。④计算oW与w,的差值，1节 能自动控制的实时计算当两者的差值最大时(OW- -Wp)m,此时对应的凝汽器压力即为机组在当前运行工况下的最佳真空，1.1凝汽器实时运行清洁系数的计算假设循环水泵变频器输出反馈即为最佳真空对应凝汽器的运行清洁系数综合反映了凝汽器的的循环水泵运行方式。最佳真空及循环水泵运行脏污程度、管束布置、不凝结气体聚集程度6,实方式的计算过程如图1所示。时计算出凝汽器的运行清洁系数，可以得到凝汽器的实时性能。运行清洁系数按照HEI公式计算2节能自动控制实现方案比较Qxc,x(4-1)(1)B.-= A xLMTDxKoxXB,xBm为实现变频循环水泵的节能自动控制,有以收稿日期: 2013-09-28中国煤化工作者简介:张利(1985- -),男，湖北襄阳人，工程师，硕士，从事汽轮机节能.MYHCNM HGE-mail: zhanglihust@163.com发电中国电力第46卷参考文献:36(1): 6-11.7] 施维新.浮动和接触密封对轴系振动影响的测试及分析J].中1]施维新.汽轮发电机组振动及事故[M].北京:中国电力出版社,国电力,2004,37(2);11-16.1999:436- 457.SHI Weixin. 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Electric Power, 2003,(责任编辑张燕)Analysis and Identification of Friction Vibration of Turbo-Generator UnitsYE Ze-ping, DAI Wei(The Commissioning and Test Istitute of Sichuan Electric Power Indutry, Chengdu 610072, China)Abstract: The axial and radial clearances of turbine- generator units are quite small. Therefore collision and friction will happen in the caseof diminishing axial or radial clearances between the rotating and the stationary parts, which will cause unit vibrations. In this paper, themechanism, occasion and location of the vibration caused by collision and friction are introduced. Through the analysis on the causes andcharacteristics of the axial and radial collision and friction, the methods for identifying the vibration under different conditions arepresented. Finally, measures to prevent the vibration in the manufacturing, installation, maintenance, startup and running of the units areput forward.Key words: steam turbine generator; cllision and friction between rotating and stationary parts; frictional vibration.++*+*+++++- +*++++*++*++*+*++(上接第61页)LI Yong, CAO Zu-qing. The concept of condenser cleaning ratePower Equipment, 2012, 26(3): 183-185.and tet method []. Turbine Technlolgy, 1995, 37(2): 73-76.]李勇,曹祖庆.凝汽器清洁率的概念及测试方法[].汽轮机技术,1995 ,37(2):73 -76.(责任编辑李秀平)DCS-Based Energy Saving Automatic Control on Variable-FrequencyCirculating-Water PumpZHANG Li, ZHANG Yu, LIU Wei-Ping, GAN Zhi-yong, WANG Jian(Tianjin Electric Power Research Institute, Tianjin 300384, China)Abstract: Based on the DCS system for operating units, a method to realize the automatic control on the energy saving of variablefrequency circulating water pump is introduced. From the viewpoint of automatic control theory, the optimal condenser vacuum and thecorresponding operation mode of the pump are obtained through the calculation of real-ime condenser clean cofficient with the repeatedcycle method. Then by comparison and analysis the implementation plan is determined for the energy- saving automatic control in whichthe matters needing atention in establishing the automatic control system as well as the igaee and snting in the implementation areproposed in details. Finlly, the calculation on a 330 MW cogeneration unit is condu中国煤化工、wer consumption ofthe pump will decrease by 3 761.6 MW . h after the automatic control is implemented.YHCNMHGKey words: thermal power plant; DCS system; variabl-frequency circulating water pump; energy-saving automatic control66