火电厂变频引风机轴系扭振特性的初步研究

发布时间：2018-10-16 09:08

【摘要】：大型风机是煤电机组的重要辅机,同时也是火力发电生产过程中耗能较大的设备。为解决此问题,近年来发电企业逐步开展了变频电动机驱动、变速运行的风机技术改造,取得了一定的节能降耗效果。然而,随着变频技术改造的实施,一些风机出现了叶片断裂、大轴断裂、联轴器损伤等设备运行故障,严重影响机组的发电生产和运行安全,因此本文拟有针对性的开展研究工作。变频辅机扭振问题的研究,对于确保热力发电设备的安全、经济运行具有重要意义。本文首先分析了火电厂引风机的运行工况和负载,明确了变频改造后引风机的运行状态和机械特性,为引风机轴系扭振的机理分析提供了理论参考。建立轴系扭振模型,并通过数值分析方法,求解轴系扭振的固有特性。然后结合电厂扭振故障现场案例,研制扭振物理试验台,对比分析扭振试验结果和数值仿真结果,主要为验证仿真分析结果的有效性,支持后续的研究。从引风机几何结构和变速调节两个方面,研究火电厂变频改造后引风机轴系扭振故障机理。分析了几何结构对引风机轴系扭振固有特性的影响,有利于合理设计引风机轴系转子;结合台山电厂变频辅机的扭振故障案例,对实际变频驱动下的引风机系统,进行了轴系扭振响应特性分析,得到了扭振的共振频率点以及不同轴位置的扭转位移。通过电机恒速运行与变速调节下引风机轴系响应特性的对比分析,电厂辅机在变频改造之后,使得引风机轴系发生共振现象,扭转位移远远大于变频改造之前的情况,易导致变频引风机轴系断裂。并从机械和电气两个方面,提出引风机轴系扭振抑制方法。论文工作对促进我国大型变频辅机的安全经济运行,具有一定的参考价值。
[Abstract]:Large-scale fan is an important auxiliary machine of coal power unit, and it is also a large energy-consuming equipment in thermal power generation process. In order to solve this problem, in recent years, power generation enterprises have gradually carried out the technical transformation of fan driven by variable frequency motor and variable speed operation, and achieved certain energy saving and consumption reduction effect. However, with the implementation of frequency conversion technology transformation, some blower have some equipment running faults, such as blade breakage, big shaft fracture, coupling damage and so on, which seriously affect the production and operation safety of generating units. Therefore, this paper intends to carry out targeted research work. The study of torsional vibration of frequency conversion auxiliary machine is of great significance to ensure the safety and economic operation of thermal power generation equipment. In this paper, the operating condition and load of the induced fan in thermal power plant are analyzed, and the operating state and mechanical characteristics of the induced fan after the transformation of frequency conversion are clarified, which provides a theoretical reference for the mechanism analysis of the torsional vibration of the shaft system of the induced fan. The torsional vibration model of shafting is established, and the natural characteristics of torsional vibration of shafting are solved by numerical analysis method. Then the physical test rig of torsional vibration is developed based on the field case of torsional vibration in power plant. The results of torsional vibration test and numerical simulation are compared and analyzed. The main purpose of this paper is to verify the validity of the simulation results and to support the subsequent research. The mechanism of torsional vibration of induced fan shafting after frequency conversion modification in thermal power plant is studied from the aspects of geometry structure and variable speed regulation of induced fan. The influence of geometric structure on the natural characteristics of torsional vibration of induced fan shafting is analyzed, which is beneficial to the rational design of shaft rotor of induced fan, and combined with the torsional vibration fault case of frequency conversion auxiliary machine in Taishan Power Plant, the actual induced fan system driven by frequency conversion is analyzed. The characteristics of torsional vibration response of shafting are analyzed, and the resonance frequency of torsional vibration and torsional displacement of different axis are obtained. Through the comparative analysis of the response characteristics of the induced fan shafting under the constant speed operation and variable speed regulation of the motor, the auxiliary units of the power plant make the induced fan shaft system resonance after the transformation of frequency conversion, and the torsional displacement is far greater than the situation before the frequency conversion transformation. Easily lead to frequency conversion induced fan shaft fracture. A method for suppressing torsional vibration of induced fan shafting is put forward from both mechanical and electrical aspects. The work of this paper has certain reference value for promoting the safe and economical operation of large frequency conversion auxiliary machine in our country.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621

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