利用试验模态分析技术研究汽机基础的自振特性

Natural Vibration Characteristics of Turbo-generator Foundation via Modal Analysis

利用模态分析理论,对某电厂660MW汽轮发电机组基础的1:10物理模型进行自振特性试验,测得该基础的结构动力特性参数(自振频率、振型、阻尼比).结果表明:汽轮发电机机组各转子在升降速过程中与基础不会发生共振;冷凝器之间框架柱及柱下部横梁梁中多次出现较大局部振动,建议在此榀柱上下横梁间加短柱连接;在50Hz±5%频率范围内出现发电机下中间平台的局部摆动,建议对中间平台进行减振处理.试验研究结果为今后基础进行动力修正和优化设计提供参考.

A natural vibration characteristics test on a physical model(scale is 1:10) of 660MW turbo-generator foundation of a power plant is made by using modal analysis. The structural dynamic characteristic parameters of this foundation, such as natural frequency, vibration mode and damping ratio, are obtained through the test. The results show that no resonance will happen between turbo-generator foundation and each rotor of turbo-generator unit during the run-up or run-down periods. It occurred many times local vibration during the frame column of the condensers and the midspan of the beam at the bottom column, this article makes suggestions that using a short column connects the upper and lower beams. Local vibration occurred on the middle platform of the generatior in 50Hz± 5%frequency range, so it is suggested vibration reduction treatments on the middle platform. This research provides areference for the dynamic modificationand optimization design of the turbo-generator foundation in the future.