Yao Dakun\曲大庄2 (1. Harbin Institute of Electric Machinery, Harbin 150040, Heilongjiang; 2 Harbin Power Equipment Co., Ltd., Harbin 150040, China) Abstract: The stator mode and vibration performance of 600MW steam turbine generator manufactured by Harbin Electric Power Co., Ltd. Experimental Research. The ellipsoidal inherent entanglement of the stator, the vibration amplitude of the base and the bearing seat and the vibration isolation system of the stator frame are given. It can be used for the design and manufacture of 600MW steam turbine generators and large steam turbine generator sets. .
Foreword With the vigorous development of China's electric power industry, the single-unit children of thermal power units are increasing, and the thermal power construction is gradually transitioning to a new situation dominated by domestic 600MW units. W. This paper introduces HEC 600MW steam turbine generators manufactured by Harbin Electric Power. Stator mode and vibration test conditions for 600MW turbine generator operation and design and manufacture of large steam turbine generator sets.
During the operation of the turbo generator, the stator will be subjected to the magnetic pull of the rotor, generating twice the system frequency of forced vibration. For a generator with a system frequency of 50 Hz, the excitation force frequency is 100 Hz and is elliptical along the circumferential direction. . If the natural frequency of the stator elliptical mode is equal to or close to 1 Hz, the base may resonate, resulting in large vibrations, affecting the normal operation of the unit and even accidents.
We obtained the experimental modal parameters of the HEC600MW turbine generator stator through experiments, and then investigated the dynamic characteristics of the stator and corrected the finite element calculation method.
Whether the design of the unit is reasonable or not will ultimately be assessed by on-site operation. On-site vibration testing and analysis is the ultimate standard for assessing its mechanical properties. Through the type test, we simulated various stress conditions in the actual operation of the site, and conducted tests and analysis to predict the vibration of the plant operation. Because the in-plant test vibration estimate is conservative, the type test is sufficient to represent the plant's operating conditions.
The vertical spring plate is used between the stator core of the HEC600MW turbo generator and the base to isolate the vibration. The vibration isolation effect is directly related to the life and normal operation of the base. The vertical spring plate structure is different from the conventional horizontal elastic positioning rib. The vibration isolation coefficient of the spring plate is determined by actual measurement to ensure the safe operation of the unit. At the same time, it is provided for the design and calculation of the vibration isolation structure of the larger capacity unit in the future.
1 Main parameters of the unit Maximum continuous output 654MW rated power factor 0.9 2 Research content 2.1 Transverse test The stator modal test is carried out on the final assembly test platform, which is completely consistent with the operation status of the unit in the power plant. The modal parameters of the test reflect the actual operation of the unit. Dynamic characteristics.
2.2 Core, base, bearing housing vibration measurement base, bearing housing vibration is required by the national standard, but also the power plant operation monitoring parameters. We conduct vibration test and analysis of the base in strict accordance with national standards and factory standards.
2.3 Spring plate vibration isolation coefficient measurement The vibration test of the type test stator core and the base is used to determine the vibration isolation coefficient of the spring plate.
3 Test methods and principles 3.1 Stator transverse test This test uses the hammer test method to use the hammer to vibrate the stator frame, measure the exciting force and acceleration response, record the force signal and response signal with the tape drive, and then send it to the person. The structural dynamic analyzer performs Fourier transform on the force signal and the response signal to obtain the frequency response function of each point, and obtains the modal parameters of the system by curve fitting the frequency response function.
When the system motion differential equation only discusses viscous damping, the displacement function of the displacement X(/) of the external force F(/) is W丨丨. The transfer function force represents a unit external force acting at the y point, and the response caused at the i point. It can be seen from the expression that the derivation of the resulting transfer function is the same regardless of which point of the machine is measured. Because it is independent of the excitation point, it is only related to the frequency and damping ratio. The numerator is related to the modal stiffness, mass, excitation point, and modal value of the response point. Therefore, the natural frequency and damping ratio can be obtained by using a transfer function; in order to obtain the vibration mode, one row or one column in the transfer function matrix is ​​required.
It can be seen from equation (4) that in order to obtain the transfer function between the points of the heart, only the excitation force (single-point excitation) is added at the y point, and the measurement is made; the response of the point can be found wy. The definition of the vibration mode It can be seen that it is not an absolute quantity (referring to a unit), but only represents the relative relationship between points, and is a dimensionless quantity.
Therefore, regularization is usually performed at a reference point (a certain diagonal component in the transfer function matrix) of I. The value itself is a relative amount. If we now use a) regularization with the reference point as 1, when the reference point is /, the Z measurement transfer function can get I...|. 1, then we can find the other transfer function of the generation. The vibration mode is obtained by multiplying the state of the state to calculate all the components of the transfer function matrix, and the dynamic characteristics of the mechanical object can be grasped.
When measuring a certain line, fix the response point at / point and move the excitation point from 1 to m; otherwise, when measuring a column, fix the excitation point and move the response point in turn, as well as The vibration mode is obtained.
3.2 Vibration measurement (3) The acceleration, velocity or displacement sensor is used to pick up the vibration signal of the measured part, enter the tape drive or digital vector filter through the preamplifier, and analyze the spectrum with the dynamic signal analyzer.
Generally, the acceleration signal vibrating in a steady state can be written as a rate; the second is the i-th harmonic amplitude; a, the second harmonic phase angle.
Perform two integrations on equation (5) to obtain the signal corresponding to the displacement. That is, during the operation of the unit, the base is mainly affected by 50Hz power frequency interference force and 100Hz frequency multiplication interference. The other harmonic vibration amplitude is very small, completely Can be ignored. Therefore, the main research frequency is 50 out and 100Hz vibration, the amplitude of 50Hz and 100Hz acceleration vibration is obtained by spectrum analysis, and the amplitude of displacement at the corresponding frequency is obtained by equation (6). Alternatively, the acquired acceleration signal is directly numerically integrated to obtain a vibration displacement; the integration can also be performed by a charge amplifier with two integrals.
3.3 Spring Plate Vibration Isolation Coefficient The spring plate is an elastic component that connects the core to the base. Its function is to reduce vibration and weaken the vibration of the core to the frame. Because the iron core is mainly vibrated by the 100 Hz electromagnetic force, the spring plate mainly isolates the 100 Hz vibration of the iron core, and the vibration isolation effect is determined by the vibration isolation coefficient K.
The 100 Hz amplitude of the core is measured by the single-point excitation method of the hammer test by the modal test of the formula (4), and 24 points are uniformly arranged along the circumference in the axial middle portion of the stator frame, and the excitation point is selected at the top of the circumference.
The vibration test points are arranged as shown in the figure.
5 test results analysis of the modal fitting to obtain the elliptical mode of the stator has a natural frequency of 123 Hz. It satisfies the requirement that the natural frequency of the elliptical mode avoids the electromagnetic force frequency *10%.
It can be seen from the amplitude and frequency of the vibration of the table 1. In the no-load and steady-state short-circuit conditions, the maximum amplitude of the pass frequency of the 11th measuring point is 21.5jun, and the amplitude of the 100Hz amplitude of the measuring point of 2 is 7jun, which satisfies the design. Claim. Other points have smaller amplitudes.
It can be seen from the vibration amplitude of the bearing block of Table 2. The vibration of the excitation end bearing seat is slightly larger than the steam end, and the horizontal direct amplitude is 8 and 21jun respectively, which are lower than the national standard 30jun, and lower than the excellent standard of Harbin Electric Company. The axial vibration amplitude is at most 17jun, which is much lower than the national standard. 38 It can be seen from the radial vibration of the iron core and the base of the table. In the rated no-load condition, the average amplitude of the 100 Hz amplitude of the two measuring points of the core is 18.5 μm. The average amplitude of the 100 Hz amplitudes of the four measuring points is 2.2 jtm, so that the vibration isolation coefficient of the elastic positioning ribs is 8.4. 6 The HEC600MW turbine generator stator base has an elliptical mode natural frequency of 123 Hz, avoiding 100 Hz electromagnetic force frequency enough. Far, it shows that the power design of the unit is reasonable. When the unit is running, the base will not generate large vibration.
The vibration amplitude of the stator of HEC600MW turbine generator is in full compliance with national standards, which can guarantee the long-term safe operation of the unit.
The test method of stator mode and vibration performance of turbo generator described in this paper is applicable to the evaluation and evaluation of generator vibration performance by new type test and field test.
Table 1 Fixed-air planting and é”±-determined road conditions 廑Amplitude peak and é“Ž rate conditions No-load steady-state short-circuit l./Né“Ž rate Through-frequency meter 2 rated speed condition, frame and bearing seat vibration ç” value And frequency pm steam end bearing housing end bearing housing base horizontal and vertical axial horizontal vertical straight table 3 rated no-load conditions, core, frame radial vibration 100Hz peak-peak Zheng Zhaochang. Mechanical vibration. Beijing: Mechanical Industry Press, 1982. Seat core
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