In addition to the vibration caused by the rotating or fixed part of the machine itself, it is also necessary to consider the influence of the electromagnetic force of the generator and the flow pressure acting on the overflow part of the hydraulic turbine on the vibration of the system and its components.
There are various causes of vibration of hydro-generator units, and several vibration sources often exist at the same time. It is generally believed that the interference force sources that cause the unit to vibrate mainly come from three aspects: hydraulic, mechanical and electrical, which affect and interact with each other, and are often intertwined to form coupled vibration.
The general vibration of the hydro-generator unit will not harm the unit, but when the vibration of the unit exceeds the allowable value, especially when the long-term vibration and resonance occur, it will bring serious harm to the power supply quality, the service life of the unit, the performance of the ancillary equipment and instruments, the foundation of the unit and the surrounding buildings, and even the safe and economic operation of the entire hydropower station.
Its harmfulness can be roughly divided into the following categories:
It causes the formation and expansion of the fatigue damage zone between the metal and weld of the unit parts, so that it will cause cracks, or even fracture damage and be scrapped.
Loosening some of the fastening parts of the unit will not only lead to the breakage of these fasteners themselves, but also exacerbate the vibration of the connected parts, prompting them to accelerate damage.
Accelerate the degree of mutual wear and tear of the rotating parts of the unit. If the large shaft swings violently, the temperature of the shaft and the bearing can be increased, and the bearing will be burned out; The excessive vibration of the generator rotor increases the wear of the slip ring and the brush, and increases the temperature, burns the bearing, and increases the spark of the brush.
The vortex pulsating pressure formed in the tailpipe can make the water crossing system oscillate, and the unit swings with force, causing cracks in the tailpipe wall, and in serious cases, the overall tailwater facilities can be damaged.
The consequences of resonance in hydro turbines are even more severe. If the resonance between the unit equipment and the plant can cause the entire equipment and plant to be damaged to varying degrees.
Hydraulic vibration is a vibration caused by the interference of the hydrodynamic pressure of the hydraulic part of the hydraulic part of the hydraulic turbine, which is called hydraulic vibration. The hydraulic factors that produce vibration mainly include: hydraulic instability caused by low-frequency vortex belt in the tail pipe, Kármán vortex, blade channel vortex, instability phenomenon in the transition process, hydraulic imbalance, cavity cavitation, interstitial jet (axial turbine), etc.
Vibration monitoring can be 24 hours a day, the vibration signal of each measurement point of the machine machinery is collected in real time, and uploaded to the cloud for data recording, analysis, and abnormal alarm, is the best means to avoid excessive maintenance, save money, pay attention to me, learn more about vibration monitoring knowledge.