Analysis On Mechamical Characteristic Of Shared Frame In Turbo Generator Set

Turbo generator set is the essential equipment in power station and frame type machineframe is the most common type to support it. During machine frame design, the problem thatconcerns the designer most is how to ensure normal and safe operation of the set. So,mechanical property of the machine frame is a key point in frame design.This paper briefly introduces the developing history of turbo generator frame design andthe research status of dynamic analysis method for generator frame. It also elaborates themethod to acquire machine frame exciting force and general research situation. Based on thetheory of modal analysis, formula of load identification in frequency domain can be deduced.Steam turbine, as the vibration source of the machine frame, its excitation characteristic is thecriteria to measure the vibration characteristic of installed machine frame and of its own.Through load identification technique, the excitation characteristic of turbo generator setinstalled on the machine frame can be identified.Aimed at the design problem of common frame used in turbo generator set as abackground, this paper elaborates as below: firstly, common frame structure shall bedesignedaccording to the installation type of the set and static analysis shall be made to ensure theframe has sufficient intensity and favorable rigidity; At the same time, in order to acquire theexciting force the frame bears during normal operation of the set, turbo generator set shall betested on the spot. After acquiring the modal and vibration response of the generator frame,the exciting force generated by the turbo generator ser when operating can be identified by themethod of least squares.At last, when making machine frame dynamic analysis, lumped massmethod shall be used and each device in the set shall be assumed to be equivalent. Rigidlyconnect the bottom of the frame and establish finite element3D solid calculation model. Byusing dynamic theory and knowledge, common frame modal analysis shall be made to acquireframe frequency and vibration type, base on which machine frame vibration displacement canbe identified by analyzing dynamic response. Base on the result of calculation, factors thatlead to vibration can be analyzed and mechanical property of the machine frame can beassessed. In order to achieve a favorable machine frame vibration characteristic, the frame and thebull shall be connected in the manner of vibration isolator. Vibration isolators should berationally selected and arranged in frame bottom and machine frame dynamic characteristic atthis time should be analyzed and calculated. At the same time, the force in the system arecalculated in order to evaluate the vibration isolation effect of the system. Compare thecalculation results with that when the frame is rigidly connected to verify the rationality ofvibration isolator selection and arrangement. Meanwhile, in comply with the design principles,amplitude method shall be selected as dynamic analyzing method for this paper to measurewhether machine frame dynamic property complies with design requirements.