CN104792517A - System for measuring in real time mechanical dynamic characteristics of spindle of water turbine - Google Patents

Abstract

The invention discloses a system for measuring in real time mechanical dynamic characteristics of a spindle of a water turbine. The system comprises a torque sensor, a grating measuring system, a phase detection unit, an A/D (analog/digital) conversion unit, a data processing unit and a computer. The grating measuring system and the torque sensor convert torque borne by the spindle into two sinusoidal signals having a phase difference; an ISP (in system programmable) analog device amplifies and filters the received sinusoidal signals; the A/D conversion unit converts analog signals into digital signals which are processed by the data processing unit; the digital signals are sent to the computer for human-machine interaction through a serial port; measuring precision is high at the constant speed, torque values of the spindle in the accelerating and decelerating states can be detected under high precision, and the system adapts to severe environments with high interference, high temperature and the like.

Description

A kind of hydraulic turbine main shaft mechanical dynamics property real-time measurement system

Technical field

The invention belongs to hydraulic turbine stability monitoring field, particularly relate to a kind of hydraulic turbine main shaft mechanical dynamics property real-time measurement system.

Background technology

The domestic STABILITY MONITORING to the hydraulic turbine at present, mainly concentrate on the phenomenon of torsional vibration monitoring aspect produced moment of torsion, the method more application is predicted in the catastrophe of Large-scale machine set, and the precision of the method is not high, and real-time is poor.

Static torque can be divided into measure and dynamic torque measurement to torque measurement according to time history at present, its measuring method can be divided into TRANSFER METHOD, balance force method and energy conversion method three class according to ultimate principle.TRANSFER METHOD is according to flexible member when transmitting torque, the change of the physical parameter produced and measure the method for moment of torsion.Here physical parameter can be the distortion of flexible member, stress or strain, and the flexible member being most commonly used to measure moment of torsion turns round axle; Balance force method measures trimming moment on body to determine the method for action torque size on machine shaft; Energy conversion method is the method according to other energy parameter measurement mechanical energy parameter and moment of torsion.In energy conversion method, torque measurement is generally indirect inspection.Different according to the transmission mode of dtc signal, contact and contactless two kinds can be divided into again.

Moment of torsion on-line monitoring has important economic implications to minimizing accident and express-analysis accident or fault.For the dynamic perfromance of hydraulic turbine main shaft system under various load and working environment, also there is no good solution both at home and abroad at present.

Summary of the invention

The object of the present invention is to provide a kind of hydraulic turbine main shaft mechanical dynamics property real-time measurement system, be intended to solve and the dynamic perfromance of hydraulic turbine main shaft system under various load and working environment is detected, also there is no the problem of good solution at present both at home and abroad.

The present invention realizes like this, a kind of hydraulic turbine main shaft mechanical dynamics property real-time measurement system, described hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises: torque sensor, optical grating measuring system, phase detection unit, A/D converting unit, data processing unit and computing machine;

Torque sensor, joint flange, generator, motor and transmission shaft, for becoming light signal in the torque conversion be subject to by main shaft, carry out opto-electronic conversion by photoelectric device, give that signal conditioning circuit carries out amplifying, shaping, filtering process;

Optical grating measuring system, is connected with torque sensor, for detecting striped;

Phase detection unit, is connected with optical grating measuring system, the striped that optical grating measuring system detects is carried out the measurement of phase differential between signal;

A/D converting unit, is connected with phase detection unit, for simulating signal being transformed into the digital signal of data processing unit identification, adopting shift register that serial signal is transformed to parallel signal, and carrying out analog to digital conversion by data processing unit Control timing sequence;

Data processing unit, is connected with A/D converting unit, controls for reading A/D converting unit being carried out to sequential control and shift register, and the result of A/D conversion is processed, and gives computing machine by serial ports;

Computing machine, is connected with data processing unit, the phase signal adopting serial ports reception data processing unit to send here, analyzes, processes and various error analysis compensation, realize the dynamic monitoring of hydraulic turbine main shaft system to signal.

Further, torque sensor comprises light source, collimation lens, key light grid, indication grating, receiving optics, the photoelectric detector that order is placed; Light source adopts light emitting diode; Key light grid adopt groove to be cut in the tangent circle grating of a roundlet, substrate of glass; Indication grating adopts the Circular gratings identical with main grating line, is carved with Liang Ge grid line district symmetrically, obtains the signal of 0 °, 90 ° respectively, and there is the gap of 1mm in two grid line intervals; Receiving optics comprises silicon photocell, photodiode and phototriode, and the locus of photovalve can adjust.

Further, key light grid, grid line dutycycle is 1/2.

Further, torque sensor is selected primary spectrum band-limiting scope, is eliminated spectra overlapping.

Further, the data processing of hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises signal acquisition circuit, signal conditioning circuit and analog to digital conversion, data processing unit;

Signal acquisition circuit realizes the acquisition of Moire fringe, and converts Moire fringe to electric signal;

Signal conditioning circuit practical function comprises: the sinusoidal signal that signal acquisition circuit exports is carried out amplification filtering, and place to go dark current;

Analog to digital conversion circuit realizes sinusoidal wave segmentation, calculates phase differential and identifies sense of rotation;

The sequential control of data processing unit conversion and control is with data processing and communicate.

effect gathers

The present invention passes through Grating torque sensor, the torque axis be subject to by main shaft is changed to the dephased sine wave signal of two-way, employing ISP In-System Programmability Programmable Analog Circuits amplifies the sinusoidal signal received, filtering, by A/D converting unit, simulating signal is converted to digital signal and data processing unit process, deliver to computing machine by serial port and carry out man-machine interaction, not only under at the uniform velocity state, there is higher measuring accuracy, and can detect with degree of precision and torque value under main shaft acceleration, deceleration state be adapted to the rugged surroundings such as various interference is strong, temperature is high.

Accompanying drawing explanation

Fig. 1 is the structural representation of the hydraulic turbine main shaft mechanical dynamics property real-time measurement system that the embodiment of the present invention provides;

Fig. 2 is the structural representation of the torque sensor that the embodiment of the present invention provides;

Fig. 3 is the tangent circle grating schematic diagram that the embodiment of the present invention provides;

Fig. 4 is the tangent circle optical grating Moire fringe schematic diagram that the embodiment of the present invention provides;

Fig. 5 is the amplification circuit diagram that the embodiment of the present invention provides;

Fig. 6 is the photoelectric switching circuit output waveform that the embodiment of the present invention provides.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Fig. 1 shows the structure of hydraulic turbine main shaft mechanical dynamics property real-time measurement system of the present invention, as shown in the figure, the present invention is achieved in that a kind of hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises torque sensor, optical grating measuring system, phase detection unit, A/D converting unit, data processing unit and computing machine;

Torque sensor, joint flange, generator, motor and transmission shaft, for becoming light signal in the torque conversion be subject to by main shaft, carry out opto-electronic conversion by photoelectric device, give that signal conditioning circuit carries out amplifying, shaping, filtering process;

Optical grating measuring system, is connected with torque sensor, for detecting striped;

Phase detection unit, is connected with optical grating measuring system, the striped that optical grating measuring system detects is carried out the measurement of phase differential between signal;

A/D converting unit, is connected with phase detection unit, for simulating signal being transformed into the digital signal of data processing unit identification, adopting shift register that serial signal is transformed to parallel signal, and carrying out analog to digital conversion by data processing unit Control timing sequence;

Data processing unit, is connected with A/D converting unit, controls for reading A/D converting unit being carried out to sequential control and shift register, and the result of A/D conversion is processed, and gives computing machine by serial ports;

Computing machine, is connected with data processing unit, the phase signal adopting serial ports reception data processing unit to send here, analyzes, processes and various error analysis compensation, realize the dynamic monitoring of hydraulic turbine main shaft system to signal.

Further, as shown in Figure 2, described torque sensor comprises light source 1, collimation lens 2, key light grid 3, indication grating 4, receiving optics 5, the photoelectric detector 6 that order is placed;

Described light source 1 adopts light emitting diode, and light source 1 is placed in the focus of collimation lens 2;

Described key light grid 3 adopt groove to be cut in the tangent circle grating of a roundlet, substrate of glass;

What key light grid 3 adopted is tangent circle grating, and substrate of glass, internal diameter 40mm, external diameter is 89mm, thick 2mm.And the grid line center of grating is on the circle of 80mm, grid region is on the circle of 75mm to 87mm; The basic parameter of key light grid is: groove is 1200 lines, and pitch angle is 0.3 °/line, and grid line dutycycle is 1/2, key light grid motion in this system.

Described indication grating 4 adopts the Circular gratings identical with main grating line.Liang Ge grid line district for axis, is carved with the glass substrate center of diameter 16mm symmetrically in groove district, can obtain the signal of 0 °, 90 ° respectively, and there is the gap of 1mm in two grid line intervals.Indication grating should have fine-tuning mechanism, to regulate the interval between it and grating scale, obtain higher fringe contrast, width simultaneously by regulating angle of cut θ to change striped, obtain each phase relation outputed signal mutually, the indication grating of Circular gratings should have eccentric adjustment (radial direction) mechanism and position phase (tangentially) adjusting mechanism.

Described receiving optics 5 comprises silicon photocell, photodiode and phototriode, and the locus of photovalve can adjust, to aim at the secondary and band of the spectral order that will receive;

Further, described torque sensor is selected primary spectrum band-limiting scope, is eliminated spectra overlapping.

Further, described key light grid, grid line dutycycle is 1/2.

Further, the data processing of hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises signal acquisition circuit, signal conditioning circuit and analog to digital conversion, data processing unit;

Signal acquisition circuit realizes the acquisition of Moire fringe, and converts Moire fringe to electric signal;

Signal conditioning circuit practical function comprises: the sinusoidal signal that signal acquisition circuit exports is carried out amplification filtering, and place to go dark current;

Analog to digital conversion circuit realizes sinusoidal wave segmentation, thus calculates phase differential accurately and identify sense of rotation;

The sequential control of data processing unit conversion and control is with data processing and communicate.

Principle of work

Pass between grating pitch (strain line spacing) W, angle between Moire fringe width B and two grating strain lines is

$\begin{array}{cc}\mathrm{tg\θ}=\frac{W}{B}& \mathrm{Fig}3.11\mathrm{Tangency\; round}\\ & \mathrm{Fig}3.12\mathrm{Moire\; fring\; e\; of}\tan \mathrm{genay}\end{array}$

When the angle of cut is very little, then B=W/ θ

Due to the number that θ angle is very little, thus 1/ θ is a larger number, and the width measuring Moire fringe so is just easy to many than measuring grating line width, therefore Moire fringe has amplification.

If θ=0, when that is the groove of two blocks of gratings is parallel to each other, the width B of striped is infinitely great.At this moment the relative movement of grating only causes the size variation of light transmission capacity, and grating resembles gate, and close when opening during irradiation light, this kind is called optical gate Moire fringe without the Moire fringe of limit for width.

The comprehensive average optical signal of what photovalve received the is groove number entering grating visual field, therefore when grating has local or short-term error δ ₀time, owing to there being many groove participation work, average effect makes error delta 0 greatly reduce, namely

As shown in Figure 3, grid line is respectively circumferentially, but the extended line of every root grid line is all cut in a radius is on the roundlet of r, and pitch angle δ is the angle between adjacent grid line for tangent circle grating.If two tangential grating pitch angles are equal, be δ, it is r that grid line is cut in radius respectively ₁, r ₂two roundlets on, as shown in Figure 4.Cut-off angle coordinate system, with grating disc center for coordinate round dot, the sequence number of coordinate axis and two grating grids is marked in figure in length and breadth, and makes two gratings No. zero grid line be parallel to x-axis.The grid line equation of grating 1 (little radius of circle is r1) is:

$y=\mathrm{tg}\left(\mathrm{n\δ}\right)\·x-\frac{r1}{\cos \mathrm{n\δ}}$

The grid line equation of grating 2 (little radius of circle is r2) is:

$y=\mathrm{tg}\left(\mathrm{n\δ}\right)\·x+\frac{r2}{\cos \mathrm{n\δ}}$

Consider grid line sequence number (n-k) to grating 2, above formula is rewritten as:

$y=\mathrm{tg}\left[(n-k)\mathrm{\δ}\right]\·x+\frac{r2}{\cos (n-k)\mathrm{\δ}}$

Separate the grid line equation of grating 1 and grating 2, the coordinate obtaining the corresponding grid line intersection point of two gratings is:

$\left\{\begin{array}{c}x=\frac{\cos [(n-k)\mathrm{\δ}\·r1+\cos \left(\mathrm{n\δ}\right)\·r2}{\sin \mathrm{k\δ}}\\ y=\frac{\sin [(n-k)\mathrm{\δ}\·r1+\sin \left(\mathrm{n\δ}\right)\·r2}{\sin \mathrm{k\δ}}\end{array}\right.$

The expression formula obtaining Moire fringe equation is:

$x^2+y^2=\frac{r_1^2+r_2^2+{2r}_1{r}_2\cos \mathrm{k\δ}}{{\sin }^2\mathrm{k\δ}}$

When k δ is enough little, formula can be reduced to:

$x^2+y^2={\left(\frac{r_1+r_2}{\mathrm{k\δ}}\right)}^2$

Sum up above-mentioned analysis, can reach a conclusion as follows:

The Moire fringe style formed is cluster is the center of circle with raster center, thinks (r ₁+ r ₂the concentric circles bunch of)/k δ radius.

Moire fringe width is the difference of adjacent two radius of interference fringes, and its expression formula is:

$W=\frac{r_1+r_2}{\mathrm{k\δ}}-\frac{r_1+r_2}{(k+1)\mathrm{\δ}}=\frac{r_1+r_2}{k(k+1)\mathrm{\δ}}$

If r ₁(or r ₂)=0, r ₂(or r ₁)=r, then

$x^2+y^2={\left(\frac{r}{\mathrm{k\δ}}\right)}^2$

The Moire fringe equation of one block of radial radiation grating that upper expression pitch angle δ is identical and one piece of concentric staked type of tangential grating.

If r ₁=r ₂=r, then

$x^2+y^2={\left(\frac{2r}{\mathrm{k\δ}}\right)}^2$

The Moire fringe equation that above formula represents that two pieces of identical tangential grating are facing when coinciding with one heart, now the expression formula of fringe position and width of fringe is:

Rk＝(r ₁+r ₂)/kδ

W＝2r/k(k+1)δ

That the present invention adopts is r ₁=r ₂the optical grating pair of=r, the Moire fringe position of generation and width are such as formula shown in upper two formulas.

Photodiode converts is adopted to be near sinusoidal ripple electric signal for the Moire fringe obtained, then there is the following two kinds situation: 1. when axle does not produce moment of torsion deformation, then sinusoidal wave without phase differential, simultaneously given light intensity is certain relative to two photodiodes, then have sinA=sinB (assuming that two diode dark current are equal).2. when axle is subject to moment of torsion generation deformation, then phase differential is Δ θ=a1-b1=arcsinA-arcsinB+0.3 ° × M+ Δ k, Δ k is the error amount that dark current produces.Then in conjunction with formula just can calculate torque value T.

In the embodiment of the present invention, indication grating, LED circuitboard, photoelectric switching circuit plate are arranged in the optical grating pair mechanism of design, then key light grid are fixed on experiment turntable, make the groove district center of key light grid and indication grating on the same line.At the uniform velocity rotate key light grid and adjustment and the distance of indication grating, make it to produce stronger Moire fringe, observe the output signal of opto-electronic conversion with oscillograph, as shown in Figure 6.In figure, A and B signal is respectively the grating sensor output signal that two main tappings of axis system are installed.Due to the actual conditions of laboratory equipment, and the impact of other various enchancement factor that can not predict together, the signal obtained has a small amount of noise.As can be seen from Figure 6, the ISP circuit of design well eliminates the dark current that photodiode produces, and achieves filter function, and filtering undesired signal, the output signal of photoelectric switching circuit has good sinusoidal waveform.

The data of carrying out calibration experiment on the torque sensor calibrating table that ratings is 400Nm shown in table 1.To the coefficient k that 6 ~ 360Nm, mono-group of data calculate, adopt the experimental data that light torch measuring system has the measurement of standard torque value load obtain a group.As can be seen from Table 1, adopt this circuit can realize the accurate measurement of moment of torsion, minimum torsional angular displacement can be surveyed and reach 0.001 °/m.

Table 1 experimental data

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that performing creative labour can make still within protection scope of the present invention.

Claims (5)

1. a hydraulic turbine main shaft mechanical dynamics property real-time measurement system, it is characterized in that, described hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises: torque sensor, optical grating measuring system, phase detection unit, A/D converting unit, data processing unit and computing machine;

Torque sensor, joint flange, generator, motor and transmission shaft, become light signal for the torque conversion be subject to by main shaft, carries out opto-electronic conversion by photoelectric device, give that signal conditioning circuit carries out amplifying, shaping, filtering process;

Optical grating measuring system, is connected with torque sensor, for detecting striped;

Phase detection unit, is connected with optical grating measuring system, the striped that optical grating measuring system detects is carried out the measurement of phase differential between signal;

A/D converting unit, is connected with phase detection unit, for simulating signal being transformed into the digital signal of data processing unit identification, adopting shift register that serial signal is transformed to parallel signal, and carrying out analog to digital conversion by data processing unit Control timing sequence;

Data processing unit, is connected with A/D converting unit, controls for reading A/D converting unit being carried out to sequential control and shift register, and the result of A/D conversion is processed, and gives computing machine by serial ports;

Computing machine, is connected with data processing unit, the phase signal adopting serial ports reception data processing unit to send here, analyzes, processes and various error analysis compensation, realize the dynamic monitoring of hydraulic turbine main shaft system to signal.

2. hydraulic turbine main shaft mechanical dynamics property real-time measurement system as claimed in claim 1, is characterized in that, torque sensor comprises light source, collimation lens, key light grid, indication grating, receiving optics, the photoelectric detector that order is placed; Light source adopts light emitting diode; Key light grid adopt groove to be cut in the tangent circle grating of a roundlet, substrate of glass; Indication grating adopts the Circular gratings identical with main grating line, is carved with Liang Ge grid line district symmetrically, obtains the signal of 0 °, 90 ° respectively, and there is the gap of 1mm in two grid line intervals; Receiving optics comprises silicon photocell, photodiode and phototriode, and the locus of photovalve can adjust.

3. hydraulic turbine main shaft mechanical dynamics property real-time measurement system as claimed in claim 2, it is characterized in that, key light grid, grid line dutycycle is 1/2.

4. hydraulic turbine main shaft mechanical dynamics property real-time measurement system as claimed in claim 1, is characterized in that, torque sensor is selected primary spectrum band-limiting scope, eliminated spectra overlapping.

5. hydraulic turbine main shaft mechanical dynamics property real-time measurement system as claimed in claim 1, it is characterized in that, the data processing of hydraulic turbine main shaft mechanical dynamics property real-time measurement system comprises signal acquisition circuit, signal conditioning circuit and analog to digital conversion, data processing unit;

Signal acquisition circuit realizes the acquisition of Moire fringe, and converts Moire fringe to electric signal;

Signal conditioning circuit practical function comprises: the sinusoidal signal that signal acquisition circuit exports is carried out amplification filtering, and place to go dark current;

Analog to digital conversion circuit realizes sinusoidal wave segmentation, calculates phase differential and identifies sense of rotation;

The sequential control of data processing unit conversion and control is with data processing and communicate.