CN1056231C - Method and apparatus for inline measuring turbine generator bearing damp - Google Patents

Abstract

The present invention relates to a method and an apparatus for on-line measurement of the bearing damping of a turbine generator set, which belongs to the technical field of vibration analysis and measurement. The on-line measurement method is realized by using the schemes of signal acquisition, characteristic signal extraction, analog-digital conversion and a spreading Prong method to carry out the schemes of characteristic signal processing, etc. The on-line measurement apparatus is composed of a vibration sensor, a characteristic signal extractor, a signal acquisition device, a characteristic signal processor, a power supply and an outer shell, wherein the characteristic signal extractor is composed of an amplifier, an active RC band-pass filter and a filter with a steep frequency attenuation characteristic, can carry out with real-time measurement to the generator set in operation, diagnoses and eliminates faults in time, and ensures safe operation.

Description

Online detection method of turbine generator bearing damp and equipment

The present invention is a kind of be used to measure turbine generator bearing damp online test method and equipment thereof, belongs to vibration analysis and technical field of measurement and test.

Turbine generator bearing damp all is to calculate (document 1, " power technology ", 1992 the 5th phases by theory analysis method at present, P42-P47 and document 2, " rotor dynamics ", P158-P165, publishing house of Tsing-Hua University), there are not special online test method and equipment thereof.Because the theoretical analysis complexity, amount of calculation is very big, can't carry out real-time analysis and calculating to operating turbine generator bearing damp, thereby is unfavorable for operating Turbo-generator Set is monitored and fault diagnosis and eliminating in real time.

The objective of the invention is at the deficiencies in the prior art, a kind of online test method and equipment thereof of turbine generator bearing damp is provided, be the safe operation of Turbo-generator Set, fault diagnosis, performance evaluation and condition monitoring etc. provides foundation.

Online detection method of the present invention is realized by following steps:

(1) utilize the sensor acquisition signal, promptly vibration signal be converted into electric signal by eddy current sensor or electromagnetic sensor,

(2) utilize the characteristic signal extraction apparatus to obtain characteristic signal, because the electric signal of sensor gained is by low frequency, the mixed frequency signal that power frequency and dither component are formed, the characteristic signal of reflection bearing damp characteristic mainly is a bearing low-frequency vibration component, and low frequency component is more much smaller than power frequency and high fdrequency component, only accounts for the logical 1%-5% of amplitude frequently usually, thereby needs to remove power frequency and high fdrequency component by the characteristic signal extraction apparatus, obtain low frequency component as characteristic signal

(3) modulus (A/D) conversion is about to analog signal conversion and becomes digital signal,

(4) utilize expansion Pu Luoni (Prony) method to carry out characteristic signal and handle, because the low frequency signal X that actual measurement obtains _t(t=1.2 ... n, n are sampling number) form X by the waveform of one group of group decay _tExpression vibration displacement value (when adopting eddy current sensor) or vibration speed value (when adopting electromagnetic sensor), it does not directly reflect the damping characteristic of bearing, need approach promptly by one group of deamplification: $\underset{j=1}{\overset{p}{\mathrm{\Σ}}}{A}_j{e}^{-\mathrm{djt\Δ}}{e}^{i(2\mathrm{\π}{f}_{\mathrm{dj}}\mathrm{t\Δ}+{\mathrm{\β}}_j)}=X_t$

A wherein _jAnd β _jBe respectively amplitude and phase place, Δ is a sampling time interval; Though employing Nonlinear System of Equations method for solving can be according to the X that records _t, obtain d _iWith

, but this method is consuming time many, and amount of calculation is big, adopts expansion Pu Luoni (Prong) method can avoid the solution procedure of Nonlinear System of Equations, can improve processing speed greatly,

(5) adopt display display process result or printer prints to go out result.

Characteristic signal in the online detection method of the present invention extracts, and can adopt earlier and be carried out the signal amplification, adopted the Active RC band-pass filter again by amplifier, and the scheme with high-precision filter filtering realizes then.Expansion Pu Luoni (Prong) method can be realized by following scheme:

(1) according to measured signal X _t, set up about X _tThe autoregression difference equation: $X_i+\underset{I=1}{\overset{p}{\mathrm{\Σ}}}{C}_1{X}_t-e={\mathrm{\ϵ}}_t$ Wherein: ε _tBe residual error; C ₁Be autoregressive coefficient, available auxiliary variable method is tried to achieve C ₁Consistent estimate,

(2) use autoregressive coefficient C ₁Construct a polynomial expression:

Z ^p+ C ₁Z ^P-1+ ... + C _P-1Z+C _p=0 usefulness quadratic factor algorithm is found the solution polynomial characteristic root Z _j(j=1,2 ... p),

(3) according to characteristic root Z _iWith d _iWith Relation obtain d _iWith

$f_{d_j}=\frac{1}{2\mathrm{\π\Δ}}\mathrm{arctg}(I_m{Z}_j/R_e{Z}_j)$ $d_j=\frac{1}{\mathrm{\Δ}}\ln \left|Z_j\right|(j=\mathrm{1,2}......p)$

Wherein: I _mZ _jAnd R _eZ _jBe respectively Z _jImaginary part and real part, | Z _j| be Z _jMould.

(4) reject false value, export correct result, right at the P that obtains

And d _iIn, have only A pair of when equating with the centre frequency of actual measurement low frequency signal And d _iReal, d at this moment _iBe desired damping factor, the centre frequency of actual measurement low frequency signal can draw by spectrum analyzer.Owing to usually adopt logarithmic decrement to represent damping in the work, thus can And d _iTurn to logarithmic decrement δ, promptly $\mathrm{\δ}=d_j/f_{d_j}$ 。

Online detection instrument of the present invention is made up of vibration transducer, characteristic signal extraction apparatus, signal picker, characteristic signal processor, power supply and shell, be characterized in that the characteristic signal extraction apparatus can adopt amplifier, the Active RC bandpass filter constitutes with the wave filter with precipitous frequency decay characteristics.Vibration transducer can adopt electromagnetic sensor or eddy current sensor.Signal picker can adopt modulus (A/D) converter to constitute.The characteristic signal processor can adopt universal microcomputer, single-chip microcomputer or dsp processor structure, takes the processing capacity of programming scheme realization to characteristic signal.

The present invention compared with prior art, it is fast and detect advantages such as reliable to have simple in structure, processing speed, it can carry out real-time analysis by online detection, is convenient to and advances diagnosis and fix a breakdown; The genset actual conditions detect owing to combine closely, and help reflecting the actual operating state of Turbo-generator Set, so that guarantee the safe operation of Turbo-generator Set.By measurement to the #6 bearing damp of homemade 200MW Turbo-generator Set, obtain the result and meet the conclusion of generally acknowledging on the engineering, under the situation of 3000 rev/mins and 3270 rev/mins, the logarithmic decrement of its bearing is 0.13 and 0.0786, and the logarithmic decrement analog value of generally acknowledging on the engineering is 0.1～0.2 and 0～0.1 scope.

Fig. 1 is the structural representation of present device; Fig. 2 is the circuit block diagram; Fig. 3 is a characteristic signal extraction apparatus electricity principle schematic.

Equipment of the present invention can adopt scheme shown in the drawings to realize.A kind of structure of portable set has 220V AC power jack as shown in Figure 1 on the shell of equipment, panel is provided with power switch C, pilot lamp D, keyboard E, frequency selection button F, display G and printer output hole H.Sensor among Fig. 2 (1) can adopt conventional electromagnetic sensor A or eddy-current transducer B; Amplifier (2) can be by ic chip ₁, and resistance R ₁₁, R ₁₂, R ₁₃Constitute; Active RC bandpass filter (3) can be by IC ₂And IC ₃, resistance R ₁₁, R ₁₂, R ₁₃Constitute; Active IC ₁, IC ₂And IC ₃Can adopt operational amplifiers such as LM324, μ A741 and LF356; Have the empty wave filter (4) of high and steep frequency attenuation characteristic and can adopt elliptic function filter in switching capacity filter or the active RC filter, for example adopt switching capacity filter integrated package MF10, circuit as shown in Figure 3.According to the needs that difference requires, amplifier (2), Active RC bandpass filter (3) and the wave filter (4) with precipitous frequency attenuation characteristic can adopt single-stage or multistage polyphone formation respectively.Modulus (A/D) converter (5) can adopt the A/D plate, so as with the universal microcomputer coupling; For Single Chip Microcomputer (SCM) system, then can adopt the ADC0804 integrated package to constitute.The characteristic signal processor can adopt Single Chip Microcomputer (SCM) system, can be made of single-chip microcomputer 8031 (6), external program memory EPROM (8), data memory RAM (7), general purpose I/O extended chip 8155 (9), printer (10), LED charactron display (11) and the keyboard (12) of routine.For fear of because of the sudden power lossing signal, equipment can be provided with conventional power-off protecting circuit (13).Active RC filter shown in Figure 3 works in the logical mode of band of particular centre frequency; Switching capacity filter can work in the logical mode of band of particular centre frequency or the low pass mode of particular cut-off frequency.For the characteristic signal of 19.8Hz, switching capacity filter works in the low pass mode, resistance and electric capacity desirable following numerical value: R ₁₁=R ₁₃=5.6K Ω, R ₂₂=5K Ω, R ₂₃=18K Ω, R ₂₄=33K Ω, C ₁=C ₂=1 μ F, variable resistor R ₁₂=30K Ω, R ₃₂=10K Ω, R ₃₃=20K Ω.

Equipment of the present invention can adopt cordwood modular structure, and it can be made up of load module, primary module, Display And Keyboard module, printer module.Load module is by the formation of characteristic signal extraction apparatus and modulus (A/D) converter, and primary module is made of 8031 single-chip microcomputers, 2764EPROM, 6116RAM, 8155 extenders and necessary logical device etc.; The Display And Keyboard module is by 14 keys (10 numerical keys wherein, 4 function key: S are that display key, P are that printing key, R are reset key for beginning feeler switch, D), 7 LED charactrons (preceding 3 display frequencies, back 4 show logarithmic decrements), 75452 drivers and necessary formations such as logical device; Printer module constitutes (as GP-16) by intelligent mini-printer, directly links to each other with 8031; Power module is made of transformer, rectification circuit, mu balanced circuit and power extension circuit, its function be will input the 220V alternating current be converted to ± 12V ,+three groups of direct currents output of 5V.Except characteristic signal extraction apparatus needs ± 12V and+5V power supply, remaining part is by+5V power supply power supply.Because present device can take the building module structure, thereby make compact conformation, volume little, be convenient to debugging and safeguard.

Claims (6)

1, a kind of online detection method that is used to detect turbine generator bearing damp is characterized in that it is realized by following steps:

(1) adopt eddy current sensor or electromagnetic sensor to gather vibration signal;

(2) employing characteristic signal extraction apparatus obtains the low frequency component in the vibration signal;

(3) analog signal conversion is become digital signal;

(4) adopt expansion Pu Luoni (Prong) method to carry out characteristic signal and handle, the characteristics of low-frequency signal of surveying is changed into the bearing damp factor and the low frequency frequency that reflects the bearing damp characteristic, this expansion Pu Luonifa is:

(i), set up autoregression difference equation about measured signal Xt according to measured signal Xt: $X_t+\underset{i=1}{\overset{p}{\mathrm{\Σ}}}{C}_1{X}_t-e={\mathrm{\ϵ}}_t$ Wherein: ε _tBe residual error; C ₁Be autoregressive coefficient, available auxiliary variable method is tried to achieve C ₁Consistent estimate.

(ii) use autoregressive coefficient C ₁Construct a polynomial expression:

Z ^p+ C ₁Z ^P-1+ ... + C _P-1Z+C _p=0 usefulness quadratic factor algorithm is found the solution polynomial characteristic root Z _j(j=1,2 ... p),

(iii) according to characteristic root Z _jWith damping factor d _jWith the low frequency frequency

Relation, obtain damping factor d _jWith the low frequency frequency

$f_{d_j}=\frac{1}{2\mathrm{\π\Δ}}\mathrm{arctg}(I_m{Z}_j/R_e{Z}_j)$ $d_j=\frac{1}{\mathrm{\Δ}}\ln \left|Z_j\right|(j=\mathrm{1,2}......p)$

Wherein: I _mZ _jAnd R _eZ _iBe respectively Z _jImaginary part and real part, | Z _j| be Z _jMould,

(iv) reject false value, export correct result, right at the P that obtains

And d _iIn, when

A pair of when equating with the centre frequency of actual measurement low frequency signal

And d _iBe real, obtain damping factor d thus _j,

(5) adopt display display process result or printer prints to go out result.

2. the online detection method of turbine generator bearing damp according to claim 1, it is characterized in that characteristic signal extracts employing and carries out the signal amplification by amplifier, use the Active RC band-pass filter again, go out the characteristics of low-frequency signal with high-precision filter filtering then.

3. one kind for implementing the custom-designed turbine generator bearing damp online detection instrument of the online detection method of turbine generator bearing damp as claimed in claim 1, form by vibration transducer, characteristic signal extraction apparatus, signal picker, characteristic signal processor, power supply and shell, it is characterized in that the wave filter that the characteristic signal extraction apparatus adopts amplifier, Active RC bandpass filter and has a precipitous frequency attenuation characteristic constitutes.

4. turbine generator bearing damp online detection instrument according to claim 3 is characterized in that the wave filter with precipitous frequency attenuation characteristic adopts switching capacity filter.

5. according to claim 3 or 4 described turbine generator bearing damp online detection instruments, it is characterized in that the characteristic signal processor is made of 8031 single-chip microcomputers, EPROM, RAM, general purpose I/O extended chip 8155, printer, LED charactron display and keyboard.

6. turbine generator bearing damp online detection instrument according to claim 5 is characterized in that adopting cordwood modular structure, is made up of load module, primary module, Display And Keyboard module, print module and power module.

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