CN102768101B - Vibration testing device for hydropower unit in hydropower station and vibration attenuation implementing method of vibration testing device - Google Patents

Abstract

A vibration testing device for a hydraulic unit in a hydropower station, including a horizontal vibration sensor, a magnetic proximity switch, a magnetic plate-type fixed reference point and a signal acquisition instrument. The four horizontal vibration sensors are respectively fixed on the two legs of the upper and lower frame, and the magnetic proximity switch The switch is fixed on the upper frame, the magnetic plate type fixed reference point is fixed on the rotating shaft, the horizontal vibration sensor and the magnetic proximity switch are respectively connected to the signal acquisition instrument; the implementation method of vibration reduction is: start the hydraulic unit to test the hydraulic unit under different loads According to the sensor signal, the position of the unbalanced mass is determined according to the test curve, and the equal-mass counterweight is carried out on the upper and lower end faces of the rotor of the unit, and the weight quality test is changed in equal proportions. Counterweight. The invention has the advantages that the test device has a simple structure, and the vibration reduction method is easy to implement and has high efficiency, which can simultaneously reduce the vibration of the hydraulic unit caused by mechanical, water flow, and electromagnetic unbalanced forces, and prolong the service life.

Description

Vibration test device for hydraulic unit of hydropower station and implementation method of vibration reduction

Technical field

The invention belongs to vibration testing and control of a hydraulic unit of a hydropower station, in particular to a vibration testing device for a hydraulic unit of a hydropower station and a vibration reduction implementation method thereof.

Background technique

On August 17, 2009, a major safety accident occurred at the Sayano-Shushenskaya Hydropower Station. First, there was a loud noise near the 2# unit, and then the top cover and rotor of the 2# turbine were shot out, and the water column was sprayed from the cavity at the turbine into the main unit. The factory building eventually caused the disastrous consequences of flooding the factory building, machine crash and death. The warnings obtained from the major safety accident of the Sayano-Shushensk Hydropower Station should arouse the attention of my country's water conservancy industry. According to the post-accident analysis, the excessive vibration of the unit was one of the important reasons for the accident.

The factors that cause the vibration of the hydraulic unit mainly include mechanical, hydraulic, and electromagnetic, and the vibration of the unit caused by the three types of factors is interrelated and affects each other. For example, when the water flow excites the vibration of the rotor of the unit, the air gap between the generator rotor and the stator will be asymmetrical, and the resulting asymmetrical magnetic pull will aggravate the vibration of the rotating part of the unit, and the rotor motion will occur The change will inevitably affect the flow field of the turbine and the electromagnetic field of the generator.

Carrying out the dynamic balance test and carrying out a reasonable and effective counterweight on the rotor of the generator set can effectively solve the vibration problem of the unit caused by the uneven mass distribution of the rotating part of the unit. The essence of the dynamic balance test is to find out the unbalanced mass and position of the rotor. At present, the installation company and the maintenance organization of the unit mostly use the three-time trial weight drawing method. This method is more complicated, and needs to switch on and off the unit multiple times, generally not less than 5 times. Moreover, the impact of unit load changes was not considered during the test, so the experiment could not minimize the vibration of the hydraulic unit.

Contents of the invention

The purpose of the present invention is to address the above-mentioned problems, to provide a vibration test device for hydropower units in hydropower stations and a vibration reduction implementation method thereof. The test device can simultaneously reduce the vibration of hydroelectric units caused by mechanical, water flow, and electromagnetic imbalance forces. The impact of unit load changes and water flow field changes can more effectively reduce and control the vibration of hydraulic units. This test method can reduce the number of startups during dynamic balance tests, reduce test costs, and improve test efficiency.

Technical scheme of the present invention:

A vibration test device for a hydraulic unit of a hydropower station, including a horizontal vibration sensor, a magnetic proximity switch, a magnetic plate type fixed reference point and a signal acquisition instrument. There are four horizontal vibration sensors and they are respectively fixed on the upper and lower machines located above and below the rotor. On the two legs of the frame, the two horizontal vibration sensors installed on the outside of each frame are 90 degrees to each other, and the directions of the horizontal vibration sensors on the upper and lower frames correspond to each other; the magnetic proximity switch is fixed on the upper frame close to the rotating shaft At the position, the magnetic plate type fixed reference point is fixed on the rotating shaft and is on the same horizontal line as the magnetic proximity switch. The distance between the magnetic proximity switch and the magnetic plate type fixed reference point is 0.5-2cm, so that when the reference point passes through the magnetic proximity switch, The switch is in the open state, and the switch is in the closed state when leaving; the horizontal vibration sensor and the magnetic proximity switch are respectively connected to the signal acquisition instrument through wires.

A vibration reduction implementation method of the hydraulic unit vibration test device of the hydropower station, the steps are as follows:

1) Install the test device in the shutdown state, then start the hydraulic unit to the rated speed, connect to the grid with load, test and record the sensor signals of the hydraulic unit under different loads;

2) Select the maximum operating condition of the horizontal vibration amplitude, and determine the position of the unbalanced mass according to the peak and valley positions of the vibration amplitude signal curve tested by the horizontal vibration sensor and the pulse signal position of the magnetic proximity switch;

3) Then stop the operation of the unit, perform equal mass counterweights on the corresponding positions of the upper and lower end faces of the rotor of the hydroelectric generator set, start the unit to the maximum vibration amplitude condition, test and record relevant signals;

4) Then stop the operation of the unit, change the mass of the counterweight in equal proportion, start the unit to the maximum vibration amplitude condition, test and record the relevant signals;

5) Finally, according to the vibration test amplitude of the two counterweights, determine the counterweight of the upper and lower end faces of the rotor of the hydraulic unit, stop the operation of the unit, and carry out counterweighting according to the calculated counterweight value, complete the work of reducing the vibration of the hydraulic unit, and the unit resumes normal operation.

Beneficial effects of the present invention:

The test device has a simple structure, the vibration reduction method is easy to implement, and has high efficiency. It can simultaneously reduce the vibration of the hydraulic unit caused by mechanical, water flow, and electromagnetic unbalanced forces. Compared with the traditional method, it is simpler and has more factors to consider. The vibration amplitude of the unit can increase the range of the high-efficiency operation area of the unit and prolong the service life of the unit. The test cost is low and has high practical value.

Description of drawings

Figure 1 is a schematic diagram of the testing device.

Figure 2 is a schematic top view of the testing device.

In the figure: 1. Upper frame 2. Lower frame 3. Rotor 4-Ⅰ, 4-Ⅱ, 4-Ⅲ, 4-Ⅳ. Horizontal vibration sensor 5. Magnetic proximity switch 6. Rotating shaft 7. Magnetic plate type fixed reference Point 8. Signal collector 9. Wire

Figure 3 is a phase comparison analysis diagram drawn with the horizontal vibration sensor in the X direction of the above frame as a reference point.

Detailed ways

Example:

A vibration testing device for a hydraulic unit of a hydropower station, including horizontal vibration sensors 4-I, 4-II, 4-III, 4-IV, a magnetic proximity switch 5, a magnetic sheet-type fixed reference point 7 and a signal acquisition instrument 8, and a horizontal vibration sensor A total of four 4-I, 4-II, 4-III, and 4-IV are set up and respectively fixed on the upper and lower racks 1 and 2 above and below the rotor 3. Each rack 1, The two horizontal vibration sensors installed on the outside of 2 are 90 degrees to each other and the directions of the horizontal vibration sensors on the upper and lower frames 1 and 2 are correspondingly consistent; the magnetic proximity switch 5 is fixed on the upper frame 1 near the rotating shaft 6, and the magnetic sheet The fixed reference point 7 is fixed on the rotating shaft 6 and is on the same horizontal line as the magnetic proximity switch 5. When the reference point 7 passes the magnetic proximity switch 5, the switch 5 is in the open state, and the switch 5 is in the closed state when leaving; the horizontal vibration sensor 4-I, 4-II, 4-III, 4-IV and the magnetic proximity switch 5 are connected to the signal collector 8 through wires 9 respectively.

The vibration reduction implementation method of the hydraulic unit vibration test device of the hydropower station, the capacity of the hydraulic unit is 200,000 kW, the radius of the counterweight is 3m, and the rated speed is 120r/min. The steps are as follows:

1) When the hydraulic unit stops running, install a horizontal vibration sensor (DPS-0.35-5-H) in two horizontal directions (X direction and Y direction) perpendicular to each other on the upper and lower frames; Install a magnetic proximity switch (DZJC-2) at the drawer, and install a fixed reference point on the rotating shaft. The distance between the magnetic proximity switch 5 and the magnetic sheet type fixed reference point 7 is 0.5cm; pass the horizontal vibration sensor and the magnetic proximity switch through the The wire is connected with the signal acquisition instrument (NI PXI-6255 multi-function data acquisition system).

2) Start the hydraulic unit, connect to the grid with load, and run stably for 5 minutes under the loads of 2, 4, 6, 8, 10, 12, 14, 16, 18, and 200,000 kW respectively, and the signal acquisition instrument records the vibration amplitude under each load value and the pulsation signal generated by the switching element; draw the curve diagram of the change process of the vibration amplitude of the sensor under each load, and select the load condition corresponding to the maximum vibration amplitude. This implementation determines that the corresponding working condition of the maximum vibration amplitude is 80,000 kW; the horizontal vibration sensor in the X direction of the above frame is used as a reference point, and the phase comparison analysis diagram is drawn, as shown in Figure 3, from the position of the pulse signal and vibration amplitude in the figure, it can be determined that the phase of the unbalanced mass is 54 degrees ahead of the reference point. For the test data of the other three sensors, a phase comparison analysis chart is also drawn to check the phase of the unbalanced mass to ensure the accuracy of the results.

3) The unit stops running. At the corresponding position where the counterweight radius of the upper and lower end faces of the hydraulic unit is 3m in the direction of the determined unbalanced phase of 180 degrees, the counterweight is 15kg respectively, and the unit is started to the corresponding working condition of the maximum vibration amplitude. The signal acquisition instrument records the relevant Vibration amplitude signal.

4) The unit stops running, and the original counterweight positions on the upper and lower end faces of the hydraulic unit are respectively counterweighted to 30kg, and the unit is operated to a load of 80,000 kW, and the signal acquisition instrument records the relevant vibration amplitude signals.

5) This implementation selects the test data of the upper and lower racks in the X direction for analysis. Assuming that the radial stiffness of the upper and lower brackets remains unchanged, and considering the change in the vibration amplitude of the bracket caused by the change of the unbalanced mass after the counterweight, according to Hooke's law and force balance, it can be calculated that the upper and lower ends of the hydroelectric generator set need a counterweight of 60kg, 80kg. The specific formula is as follows:

F=kx

In the formula, F is the load, K is the stiffness, and X is the displacement value.

According to the mass change of the two counterweights, the relationship between the centrifugal force and the test displacement value can be obtained by using the above formula:

$\mathrm{<span\; class="notranslate">\; \&Delta;m</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>$

In the formula, △m is the mass difference of the two counterweights; ω is the angular velocity of the unit; r is the radius of the counterweight; k ₁ and k ₂ are the radial stiffness of the upper frame and the lower frame respectively; Respectively, the displacement amplitudes of the first and second tests of the counterweight on the upper frame; are the displacement amplitudes of the first and second tests of the counterweight of the lower rack, respectively.

According to the above formula, the radial stiffness k ₁ and k ₂ of the upper frame and the lower frame can be calculated. Then according to the displacement amplitude test results before the counterweight, the following formula is used:

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 0</span>}}$

${\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 0</span>}}$

m ₁ and m ₂ are the counterweight mass required for the upper and lower racks; are respectively the displacement amplitudes of the horizontal sensor when the upper and lower racks are under the working condition corresponding to the maximum vibration amplitude of the unit and without counterweight.

Stop the operation of the unit, the original counterweight positions of the upper and lower ends of the hydraulic unit, the counterweights are 60kg and 80kg respectively, and the unit resumes normal operation.

Claims (1)

1. the vibration damping implementation method of a hydraulic unit vibration proving installation, described vibration-testing apparatus comprises horizontal vibration sensor, magnet proximity switch, magnetic sheet permanent datum and signal sampler, horizontal vibration sensor arranges four and be separately fixed at and be positioned on two supporting legs of the above and below upper and lower frame of rotor altogether, and the horizontal vibration sensor orientation that two horizontal vibration sensors that install in the outside of each frame are mutually in 90 degree and upper and lower frame is corresponding consistent; Magnet proximity switch is fixed on upper spider near rotating shaft place, magnetic sheet permanent datum is fixed in rotating shaft and with magnet proximity switch on same level line, the distance of magnet proximity switch and magnetic sheet permanent datum is 0.5-2cm, make when magnetic sheet permanent datum passes through magnet proximity switch, magnet proximity switch is opening state, and while leaving, magnet proximity switch is closure state; Horizontal vibration sensor is connected with signal sampler by wire respectively with magnet proximity switch, it is characterized in that step is as follows:

1) stopped status installation testing device, then starts hydropower unit to rated speed, and the horizontal vibration sensor signal of hydropower unit under different load is tested and recorded to grid-connected on-load;

2) selection level vibration amplitude maximum duty, according to the crest of the vibration amplitude signal curve of horizontal vibration sensor test, wave trough position and magnet proximity switch pulse signal location positioning unbalance mass, position;

3) then stop hydropower unit operation, the quality counterweight such as in relevant position, hydroelectric generator group rotor upper and lower end face, carry out, start hydropower unit to vibration amplitude maximum duty, test and record coherent signal;

4) then stop the operation of hydropower unit, equal proportion changes weight mass, starts hydropower unit to vibration amplitude maximum duty, tests and record coherent signal;

5) finally according to the vibration amplitude of twice weight mass test, determine the weight mass of hydroelectric generator group rotor upper and lower end face, stop the operation of hydropower unit, according to calculating weight mass, carry out counterweight, complete and reduce hydropower unit vibration work, hydropower unit recovers normal operation.