So far, the monitoring system of most hydropower plants in China has not monitored the vibration swing value of the unit. Some small hydropower plants that have realized the whole plant monitoring have not achieved the measurement of the vibration swing, and they have stayed at the stage of use percentage. . Today's hydropower plants are vigorously promoting the application of computers, and the transformation of the automation of basic components is also endless. However, the measurement of the vibration swing of the turbines is still stagnant, and many of the original manual methods are still used. This uncoordinated phenomenon is the negligence of the designers of the monitoring system, or the vibration swing of the unit is not important to the monitoring system, or the modification of the measurement method of the vibration swing value is the first class of the apricot history power generation unit. The big thing is negligible, 2 the importance of realizing the on-line measurement of the hydro-generator set vibration swing. The fault of the hydro-generator set vibration swing is a gradual or loss type, which will not suddenly affect the normal power generation of the unit, then the turbine group vibrates. Whether the modification of the pendulum measurement method is required, vibration is the most important source of information in the operating equipment, and the vibration signal contains various kinds of fault information. When any machine is in operation, the working state changes, and it will inevitably Reflected in the vibration signal. The most common method for the application of 0 before and after is to use the sway signal to discriminate the state of the machine. The modification of the vibration swing position measurement method of the turbine unit is a requirement of scientific and technological progress. For small hydropower that does not realize computer monitoring, the on-line measurement of the turbine pendulum vibration swing is realized, the vibration swing data of the large foot unit is saved, and the state of the unit is known. Actively develop maintenance and maintenance of the 1st state maintenance; today, vigorously promote the use of computer monitoring system, real-time online monitoring of the unit's vibration swing is even more essential. Progress said that the development of fault diagnosis technology, judging the operating status of the unit, and implementing state maintenance are the guarantees for the unattended operation of the hydropower plant and the closure of the whole plant.
Characteristics of the vibration fault of the 3 hydro-generator unit The vibration swing of the hydro-generator unit has its particularity compared with the general rotating machine. It is the coupling of the hydro-mechanical electromagnet.
It is necessary to conduct an analytical study on the type of vibration caused by the source of the vibration. In addition, the rated speed of the hydro-generator 较低 is lower, especially compared with the thermal power unit, which is usually a few hundred turns per minute, the vibration swing signal of the turbine, low frequency or ultra-low frequency. In particular, the vibration frequency caused by the hydraulic factors of the turbine is ultra-low frequency, up to 0.5.
4 The technical difficulty in realizing the on-line measurement of the hydro-generator set vibration swing is based on the low-frequency or ultra-low-frequency characteristics of the hydro-generator set vibration swing signal. The low-frequency or ultra-low-frequency vibration displacement sensor and the eddy current sensor must be used. The research on the vibration displacement sensor of low frequency or ultra low frequency has made a substantial breakthrough and the productization is that the domestic non-contact eddy current sensor has achieved the same performance as the imported one in recent years, and the price is cheaper and popular, and it is also nearly 10 Years of the year.
There are many difficulties in the technical monitoring of the vibration swing of the unit. Firstly, the field environment used by the instrument is poor, the electromagnetic interference is large, the temperature changes and the humidity is also large. The long-term online working mode requires the instrument to have a higher portable measuring instrument than the portable measuring instrument. Reliability and availability; Secondly, most of the sensor installation environment is quite different from that in the laboratory. The long-term vibration of the bracket itself increases the measurement error, such as the long-term use of the nut with a fixed pitch of 12 The eddy current sensor probe is vibrating due to the bracket itself. 5 On-line monitoring of the hydro-generator vibration swing and analysis system The series 82 vibration swing monitoring instrument produced by Shenzhen Diyou Electronics Co., Ltd. has been in operation since it was put into use in 1987. For more than ten years, after a period of development, hydropower plants inside and outside the Guangdong power system have been widely used and in good condition. The first generation product 82, the swing vibration monitor is mainly to improve the structure of the first generation products, improve the communication interface and other functions, improve the anti-interference ability, make it productized and modular, facilitate installation and maintenance, improve the accuracy and stability of the instrument. . For the installation of the non-contact eddy current sensor for measuring the swing, the most advanced foreign technology is introduced to lock the position of the probe, effectively preventing the probe from being worn due to the looseness of the probe during use and the instrument not working properly; meanwhile, Improve data measurement and data processing technology to make the equipment fully adapt to the lower limit frequency of unit vibration. The 21-swing vibration monitor was first tested in the Institute of Metrology of the Chinese Academy of Sciences in 1998. It was applied to the Wan'an Hydropower Plant in Jiangxi Province in October 1999 and successfully connected to the computer monitoring system of Wan'an Hydropower Plant.
BZFX rotating machinery vibration swing analysis system is based on BZJXX online monitoring site vibration swing or temperature, pressure and other related parameters of the unit for data acquisition and analysis, refer to the unit operating conditions volute pressure tail water pressure tile temperature load speed, etc. Automatically carry out over-limit alarm and analysis, judge the operating state of the unit according to the amplitude change and frequency change of the vibration swing, and infer the fault nature of the unit; and according to the amplitude and spectrum of the long-term stored vibration swing Trend analysis predicts the time when the unit will be faulty, providing a strong basis for the power plant to develop maintenance plans and achieve state maintenance.
3 è¿Ž çš„ çš„ 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 854 The meter is based on enough information. According to relevant data analysis, yes. For a hydropower unit, the better detection is about 37 points.
but. For a hydropower plant, it is necessary. It is still impossible to install so many sensors at the beginning. In fact, it is more secure to adopt a step-by-step approach. At present, we have designed 17 detection points. The mechanical vibration signal acquisition is mostly concentrated on the main shaft and the upper and lower frames. The hydraulic pressure signal used for analyzing the hydraulic factors mainly selects the top cover tail pipe volute and the like. The generator mainly considers the extreme frequency vibration of the iron core.
3.2 Feature extraction should fully reflect the characteristics of the failure mode. For hydro-mechanical machines, and other rotating mechanical samples, set the important characteristics of the amplitude of the foot vibration spectrum and the axis of the spindle. These are the most basic means used by domestic and foreign mechanical condition monitoring systems. This system is no exception. Of course, the correctness of these feature extractions and the comprehensive utilization of how to improve are very different and very important things.
3.3 The choice of identification mode should be appropriate. The choice of identification mode. We mainly consider the following points: 1 can fully accommodate all the necessary feature letters, and the fault identification mode can not emphasize the demand for fault samples, because the available samples are few or even No, it has a strong learning function, especially when it is difficult to obtain a typical sample of mechanical equipment in the initial stage. It must be able to accept external guidance and have a self-learning function to continuously improve the ability to identify and expand. The ability to expand information communication and progress to expand knowledge, openness. Can be integrated with other state recognition systems, become an integral part, or easy to integrate with other systems.
There are many ways to identify the mechanical state of the hydropower unit, and it is difficult to carefully try it out. After a preliminary analysis, we chose to use knowledge as the basis, and the rules for logic and reasoning.
It is true that Ding lacks the example of hydropower unit failure, and the essential understanding of the unit fault characteristics will be a long-term process. It is a trend analysis and state tracking technology. It uses signal analysis methods to capture fault signs and gradually improve the fault conditions. It is possible to realize that it is possible to meet the requirements of the unit for maintenance.
Zhou Shumei, general manager, professor, engaged in the development and research of digital signal analysis and hydroelectric vibration measuring instruments.
Huang Zongbi, male, master, engineer, engaged in the development and research of hydropower unit condition monitoring devices.
6 Conclusion The on-line monitoring of the hydro-generator unit vibration swing multiplier and other parameters such as noise temperature and pressure deformation differential resistance are important sources of unit failure. Only by realizing the measurement of the straw and violating the inherent relationship between these parameters and the equipment failure, can the state maintenance and fault diagnosis be truly realized, and the unattended operation mode can be more effectively guaranteed.
Mao Yujing, senior engineer, manager of Shenzhen Diyou Electronics Co., Ltd., a single-chip computer engaged in real-time online monitoring of hydro-vibration vibration swing
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