【作者】 胡杰；

【导师】 彭新民；

【作者基本信息】 天津大学 ， 水利水电工程， 2004， 硕士

【摘要】 上世纪五、六十年代,我国兴建了许多水电站,这些水电站,至今依然为国家的经济建设发挥着巨大作用。但是经过几十年的运行,这些电站都存在着不同的的问题,比如裂缝、振动等,此外,还面临着增容扩容等问题。如何确保这些老电站安全高效运行,如何对老电站进行技术改造,应该进行必要的论证。本文结合黄河青铜峡水电站实际工程,对老电站技术改造进行了全面的技术可行性论证。所研究的虽然是个案,但是研究的方法和手段具有普遍性和共性。通过建立青铜峡水电站的整体结构试验模型、有限元计算模型、水流数值模拟计算模型,全面分析了尾水管中墩改造和水轮机更换对电站结构和水流带来的影响。同时还分析研究了由水力机械和电气三方面原因引起的18种振源,根据分析结果进行了共振校核以及分析技改对共振范围的影响,并针对共振校核中出现的问题,提出了几点建议。另外,对青铜峡电站结构上所特有的平压水箱进行了再研究,反思了原来的设计思想,总结了几十年来对此问题的研究成果。本文在这些方面得出如下主要结论:(1)从试验和计算的结果分析来看,尾水管中隔墩技术改造,受其影响相对最大的部位就是尾水管,特别是需要拆除的中墩头所在部位;但是技术改造并不会给尾水管顶板和底板的钢筋配筋量带来变化;按现行规范计算,尾水管底板原有钢筋量存在不足。试验过程中通过模拟快速施工的方法测试自重应力取得理想效果。(2)水电站厂房容易与由推力瓦制造不良引起的激振力和由蜗壳不均匀流场引起的激振力发生共振,尤其是当机组出力需要经常大幅度变化时,更要引起注意。对此,需要从水轮发电机和蜗壳流道的设计、制造、安装等方面加以解决,同时,也应尽量避免在某些可能产生强烈振动的负荷区运行。尾水管技术改造对电站厂房自振频率有影响,但是影响不大。比较而言,更换了水轮机很有可能扩大了共振频率的范围。这个问题值得重视。(3)平压水箱对改善某些部位的应力状态有一定的作用,但是并没有原设计考虑的那么明显,加强对平压水箱的现场观测,结合计算和试验,是比较合理的选择。(4)尾水管出流不均匀现象得到验证。中墩技术改造对改善这种不均匀性有一定作用,使得水流更加顺畅,但是作用并不是很明显,对两孔的影响程度也不一样。更多还原

【Abstract】 A large number of hydropower stations had been built up during the 50 and 60’sin the last century. These hydropower stations had been making great action on Chineseeconomic progress. There are many problems in these old hydropower stations afteroperation for so many year, such as crack, vibration and so on . It should bedemonstrated that how to make the old hydropower stations more efficient and how tocarry out the technical improvement.In this article, taking the Qingtonggorge hydropower station as an example, thetechnical feasibility to the improvement of the old hydropower stations was demonst-rated.Although the study was a special case , the approaches and means were common,Because of the modification and the replacement of the water turbine, the effects to thestructure and the fluid were roundly analyzed by building up the physical、FEM andfluid model. Also eighteen kinds of vibration source from the hydraulic, mechanic andelectrical factors were analyzed. According to the analytical results, the resonance wascalibrated and the effects to resonance brought by the modification was analyzed . Afew pieces of suggestion were put forward in the light of the problems occurred duringthe resonance calibration. In addition, the balance water tank which was the uniquestructure of the Qingtonggorge hydropower station was studied again. The thoughts ofthe design were analyzed and the researching results during the past years weregeneralized. The main conclusions were drawn as follows:(1) According to the results of the test and calculation , the mostly affectedposition was the draft tube, especially the location which would be removed. Theamount of reinforcement bar in the bottom and upper plates was not affected by themodification. Calculated through the current standards, the amount of the reinforcementbar in the bottom plate of the tail pipe was not enough. By simulating the rapidconstruction method, the test to the body stress was successful.(2) The resonance between the powerhouse structure and the centrifugal forcewhich is induced by the poor manufacture of the thrust bushing and the non-uniformpotential field in the scroll case is easily provoked, which should be paid attentionespecially when the output of the power station needs to be changed frequently andgreatly. Improving the design, manufacture and installation of the power generator andthe flow path of scroll case could solve this problem. At the same time, it is better toavoid the operation in the region where strong vibrations are possible to happen. Thereis some effect to the resonance brought by the modification, but the degree isn’t large.By comparison, the replacement of the water turbine easily widen the scope of theresonance, which should be paid attention to.(3)The balance water tank could improved the state of the stress in somelocations, but the effect was not agreed with what the design had expected. It wasreasonable to strengthen the field measurement combining with the FEM calculationand the model test.(4)Through numerical simulation, the non-uniform of the draft tube flow wasimproved. The modification of the draft tube mid-pier made the flow smoother. But theeffect was not evident and the degree to the two holes was different.更多还原