CN104820122A - Optical fiber voltage sensing system and method for obtaining phase difference related with voltage - Google Patents
Optical fiber voltage sensing system and method for obtaining phase difference related with voltage Download PDFInfo
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- CN104820122A CN104820122A CN201510180942.7A CN201510180942A CN104820122A CN 104820122 A CN104820122 A CN 104820122A CN 201510180942 A CN201510180942 A CN 201510180942A CN 104820122 A CN104820122 A CN 104820122A
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Abstract
The invention provides an optical fiber voltage sensing system, including a control module, a sensing module and an isolation optical cable, wherein the isolation optical cable is connected with the control module and the sensing module. The invention also provides a method for obtaining phase difference related with voltage. The method uses a Pockels electro-optical effect as an optical phase modulator to improve measuring accuracy of a polarimeter, can effectively eliminate influence of time-variant characteristics such as external mechanical vibration and environment temperature on a measuring result, a voltage waveform obtained by measurement is not influenced by strong electromagnetic interference, and thus measured data is more accurate; and the method for obtaining phase difference related with the voltage also ensures safety of a secondary low-voltage loop and personnel under an abnormal condition of a primary high-voltage loop.
Description
Technical field
The present invention relates to a kind of technical field of optical fiber sensing, particularly relate to a kind of method of optical-fibre voltage sensor-based system and acquisition and voltage dependent phase difference.
Background technology
When light is propagated in sensing unit, surveyed physical quantity with (treating) and interact, change the polarization state of optical electric field, thus the information of measurand is loaded on light wave.In order to be extracted by the physical quantity information that light wave loads, optical system is generally made up of a pair polarizer of mutual orthogonal and the sensing unit that clips between them; Such optical system is called polarimeter.
Optical fiber, as the wave director of light wave, is the basic device of optical fiber sensing system.Because its bendable breaks, propagation distance is far away, easy to use; Again because it is insulator, not by the impact of electromagnetic interference (EMI), optical fiber sensing system has lot of superiority.But, due to the effect of light unisexuality physical influence, any point on fiber optic conduction path, when being subject to the affecting of mechanical vibration or variation of ambient temperature, all will there is uncontrollable change in the polarization state at this some place in the light wave conducted in optical fiber, make optical fiber have time-varying characteristics as birefringent elements.
Usually, fiber polarimeter respectively has an optical fiber in the front and back that polarizer is right; Incident light is sent into polarimeter by optical fiber above, and polarimeter emergent light is sent back to by optical fiber below.Because polarimeter is very responsive to the polarization state of incident light, incident optical makes fiber polarimeter inevitably have time-varying characteristics as the time-varying characteristics that birefringent elements has.The optically-coupled of the temperature characterisitic of light source aging, photoelectric detector in time, light source and optical fiber, optical fiber and photoelectric detector, light and optical fiber collimator etc. makes these sensor-based systems can not be practical with the time-varying characteristics that the change etc. of ectocine produces.
Voltage transformer (VT) a kind of under high voltage environment, measures high-tension electronic equipment, tradition be all measured by voltage transformer (VT) high-tension.Under the high voltage environment of transformer station, due to the atmospherical discharges (corona) of wire, heavy current impact, the strong electromagnetic that the hard arc radiation etc. that isolator operation produces causes, mutual inductor can be caused to send distortion data or garble, sometimes even can damage electronic circuit, make its permanent failure.Electromagnetic compatibility (EMC) is the technical matters that it must face.
Because optical fiber is not by the impact of electromagnetic interference (EMI), it and electric light are steeped the passive optical fibre voltage sensor that Ke Ersi (Pockels) crystal combines produced, for voltage transformer (VT) provides the ideal solution of electromagnetic compatibility problem.Passive refers to that the sensing module be under high voltage environment carries out powered operation without the need to commercial voltage, and sensing module relies on pure optical principle to carry out induced voltage information.
Prior art also has and uses photoelastic effect or bubble Ke Ersi (Pockels) photoelectric effect as optical phase modulator to improve polarimeter measuring accuracy, but because light voltage sensor system has time variation, make the analysis of data very complicated and the result measured exists larger error.
Summary of the invention
The technical problem to be solved in the present invention, be to provide a kind of method being obtained measured value by optical-fibre voltage sensor-based system, owing to adopting pure optical measurement principle, light source is in control module, and power without the need to source power supply at sensing module place, measure the impact of the time-varying characteristics that the voltage waveform obtained is not produced by the system element such as strong electromagnetic and optical fiber.
The present invention is achieved in that
A kind of optical-fibre voltage sensor-based system, comprise control module, sensing module and isolation optical cable, described isolation optical cable is connected with described control module, described sensing module respectively.
Further, described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, 1/4 wavelength plate;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light transfers to described bubble Ke Ersi element successively, described first analyzer, the input end of described second optical fiber collimator, its another road optical transport is to described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate successively, described second analyzer, the input end of described 3rd optical fiber collimator, its another road light transfers to described 3rd analyzer successively, the input end of described 4th optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator is all by Fiber connection to described isolation optical cable.
Further, described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, 1/4 wavelength plate;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light transfers to described second analyzer successively, the input end of described 3rd optical fiber collimator, its another road light transfers to described bubble Ke Ersi element successively, described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate successively, described 3rd analyzer, the input end of described 4th optical fiber collimator, its another road light transfers to described first analyzer successively, the input end of described second optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator is all by Fiber connection to described isolation optical cable.
Further, described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, the one 1/4 wavelength plate, the 2 1/4 wavelength plate, the 3rd beam splitter, the 4th analyzer, the 5th optical fiber collimator;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light is connected to described bubble Ke Ersi element successively, described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 2 1/4 wavelength plate successively, described 3rd analyzer, the input end of described 4th optical fiber collimator, another road light sent from described second beam splitter transfers to described first analyzer successively, the input end of described second optical fiber collimator, another road optical transport sent from described first beam splitter is to described 3rd beam splitter, by described 3rd beam splitter, light is divided into two-way, wherein a road light transfers to described one 1/4 wavelength plate successively, described second analyzer, the input end of described 3rd optical fiber collimator, another road light sent from described 3rd beam splitter transfers to described 4th analyzer successively, the input end of described 5th optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator, the output terminal of described 5th optical fiber collimator is all by Fiber connection to described isolation optical cable.
Further, described control module comprises light source, phase-modulator, modulation voltage generator, photoelectric commutator, digital to analog converter, signal processor, described light source is connected with the input end of described phase-modulator by the connector C1 of optical fiber, the output terminal of described phase-modulator is connected in described isolation optical cable by the connector C2 of optical fiber, described modulation voltage generator is connected to described phase-modulator, isolation outgoing optical fiber in described isolation optical cable is all connected with described photoelectric commutator, described photoelectric commutator is connected to described signal processor via described digital to analog converter.
Further, described first beam splitter, described second beam splitter, described 3rd beam splitter are non-polarizing beamsplitter.
Further, described optical fiber is single-mode fiber.
Obtain the method with voltage dependent phase difference, described method needs the optical-fibre voltage sensor-based system providing the invention described above, and described method specifically comprises the steps:
Step 1, start described control module power supply after, the laser sent by described light source is entered in described phase-modulator by optical fiber, and then enters in the incident optical of described isolation optical cable;
Step 2, described modulation voltage generator is by generation one constant amplitude and have periodic stepwise voltage, is then modulated by the Signal transmissions of this voltage to described phase-modulator, modulated voltage signal is loaded on light wave and forms light modulated;
Step 3, this light modulated transfer in the described sensing module under electric field action by the incident optical in described isolation optical cable, with information of voltage in the light path of now described sensing module, then this light modulated is transferred in the outgoing optical fiber of described isolation optical cable, then transfer in described photoelectric commutator;
Step 4, the light intensity signal in described photoelectric commutator is converted to electric signal after, by described modulation voltage generator, sample clock pulse is controlled, then by described digital to analog converter to conversion after electric signal sample;
Step 5, obtain one group of intensity signal by sampling, then by described signal processor, process is carried out to this group intensity signal and calculate, system function, intrinsic function can be calculated, then build intrinsic function group by described intrinsic function;
Step 6, by this intrinsic function group, calculate total phase differential (Θ+θ of described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ;
Step 7, total phase differential (Θ+θ by described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ, calculate the electroluminescent phase differential θ with voltage in proportion
v.
Further, described step 5 is specific as follows:
Step 51, the light intensity general expression sent by the outgoing optical fiber of described isolation optical cable are:
I(t)＝(1/2)γ(t)I
o(t){2α+cos2(ψ
P-ψ
M)β+sin2(ψ
P-ψ
M)η·cos[θ
M(t)]+sin2(ψ
P-ψ
M)ζ·sin[θ
M(t)]}，
And α={ [cos
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)] cos
2(ψ
s-ψ
v)+[cos
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)] sin
2(ψ
s-ψ
v)] cos
2(ψ
v-ψ
a)+{ [cos
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)] sin
2(ψ
s-ψ
v)+[cos
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)] cos
2(ψ
s-ψ
v)] sin
2(ψ
v-ψ
a)
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, ψ
pthe light transmission shaft orientation representing the polarizer, ψ
mthe fast axis orientation representing phase modulation component, θ
mt () is the phase differential or phase delay that represent that phase modulation component produces, ψ
sthe fast axis orientation representing isolation optical fiber entrance port, ψ
vthe fast axis orientation representing sensing element, ψ
abe the light transmission shaft orientation representing analyzer, β, η, ζ all represent intrinsic function;
The angle in the light transmission shaft orientation of the polarizer and the fast axis orientation of phase modulation component is set to 45 degree, i.e. (ψ
p-ψ
m)=45 °, then general expression can be changed further and is kept to:
I(t)＝(1/2)γ(t)I
o(t){1+η·cos[θ
M(t)]+ζ·sin[θ
M(t)]}，
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mt () is the phase differential or phase delay that represent that phase modulation component produces, η, ζ all represent intrinsic function;
All there are three kinds of modulation conditions each modulation period, are respectively θ
m(t)=+ θ
m, θ
m(t)=0, θ
m(t)=-θ
m, then its one group of intensity signal { I obtained that samples
+, I
0, I
-be respectively:
I
+(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]+ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
I
0(t)=(1/2) γ (t) I
ot () { 1+ η }, wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, η represents intrinsic function;
I
-(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]-ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
Step 52, the light intensity signal { I obtained by sampling
+, I
0, I
-, the system function I calculated
m, intrinsic function ζ and η be respectively:
I
m=[I
+(t)+I
-(t)-2I
0(t) cos (θ
m)]/tan (θ
m/ 2), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition;
ζ=[I
+(t) – I
-(t)]/I
m(t), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
mt () represents system function;
η={ 2I
0(t)-[I
+(t)+I
-(t)] }/{ I
m(t) tan [θ
m/ 2] }, in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition, I
mt () represents system function;
Wherein, system function I
mt () is defined by following formula: I
m(t)=γ (t) I
o(t) sin [θ
m];
Intrinsic function ζ and η is having based on during described sensing module:
ζ=ζ
tcos2 (ψ
v-ψ
a)+ζ
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
ζ
t=sin2 (ψ
s2-ψ
v) sin (θ
s), ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
η=η
tcos2 (ψ
v-ψ
a)+η
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
η
T＝-sin2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)-cos2(ψ
M-ψ
S1)sin2(ψ
S2-ψ
V)·cos(θ
S)，
η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)
·cos(θ
V)cos(θ
S)+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 53, the angle between the fast axis direction of bubble Ke Ersi element and the light transmission shaft direction of analyzer is set to 45 degree, i.e. (ψ
v-ψ
a)=45 °, so intrinsic function ζ and η becomes respectively:
ζ=ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
s2the fast axis orientation representing isolation fiber exit mouth, ψ
vthe fast axis orientation representing sensing element, θ
srepresent that isolation optical fiber gross phase postpones, θ
vthe phase differential or phase delay that represent that sensing element produces;
η＝η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)
-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)·cos(θ
V)cos(θ
S)
+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 54, get ζ
rS=cos2 (ψ
s2-ψ
v) sin (θ
s)=Ksin (Θ) and ζ
r4=cos (θ
s)=Kcos (Θ), so ζ
r=Ksin (Θ+θ
v) and tan (Θ)=ζ
rS/ ζ
r4=cos2 (ψ
s2-ψ
v) tan (θ
s);
Wherein, Θ is that the equivalent phase introduced by isolation optical fiber is poor, and it is by external force, as mechanical vibration or variation of ambient temperature etc. act on the path of isolation optical fiber, is formed, have time-varying characteristics through accumulation; ψ
vthe fast axis orientation representing sensing element, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
sbe represent that isolation optical fiber gross phase postpones, K is the coefficient of light path;
The structure of the light path of step 55, sensing module is the intrinsic function ζ relative to basic light path
rT=Ksin (Θ+θ
v), another road light path can be built, make the intrinsic function of its light path be ζ
rR=Kcos (Θ+θ
v), there is the intrinsic function group { ζ on following 4 tunnels
rT, ζ
rR, ζ
rS, ζ
r4or { η
rT, η
rR, η
rS, η
r4}:
ζ
rT=Ksin (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rR=Kcos (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rS=Ksin (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
ζ
r4=Kcos (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
η
rT=Msin (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rR=Mcos (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rS=Msin (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing;
η
r4=Mcos (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing.
Tool of the present invention has the following advantages: the present invention utilizes bubble Ke Ersi (Pockels) photoelectric effect as optical phase modulator to improve polarimeter measuring accuracy, effectively can eliminate the time-varying characteristics such as exterior mechanical vibration and environment temperature to the impact of measurement result, and measure the impact that the voltage waveform obtained is not subject to strong electromagnetic, make the data of measurement more accurate; Present invention also ensures secondary low-voltage loop and the safety of personnel under high tension loop abnormal conditions.
Accompanying drawing explanation
The present invention is further illustrated in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is the schematic diagram being produced electroluminescent phase differential by bubble Ke Ersi effect.
Fig. 2 is one-piece construction schematic diagram of the present invention.
Fig. 3 is the basic light path composition of optical fiber sensing system.
Fig. 4 is the structural representation of control module.
Fig. 5 is the light path-3 line structure schematic diagram of sensing module.
Fig. 6 is the light path-3 line structure schematic diagram of sensing module.
Fig. 7 is the light path-4 line structure schematic diagram of sensing module.
Fig. 8 is the inventive method flowchart.
Fig. 9 is the graph of a relation of sampling clock and modulation voltage and each light path light intensity.
Embodiment
Under external force, its refractive index can become has directivity, form dielectric grid to some material.Thus, when polarized light is through this material, on orthogonal principal-axes coordinate direction, the light component of polarization is propagated with slightly different speed.An additional phase differential can be produced between the polarized light component of transmitted light on orthogonal two principal-axes coordinate.
Some crystal, under external electric field E effect, also can produce electric birefringence effect.As shown in Figure 1, when polarization direction and direction of an electric field accompany the light entrance crystal of 45 degree, the constant amplitude component of light on two directions parallel and vertical from direction of an electric field is propagated with different speed.Through the phase differential θ that light is formed between this two component
vproportional with electric field strength E, i.e. θ
v=PE, this effect is electric light bubble Ke Ersi (Pockels) effect.When the direction of propagation of light is vertical with direction of an electric field, be referred to as cross electro-optical effect; When the direction of propagation of light is parallel with direction of an electric field, be referred to as longitudinal electro-optic effect.
There is the crystal of electric light bubble Ke Ersi (Pockels) effect as basic sensing element, be equipped with the optical fiber of various polarization optical element and conduction light wave again, optical-fibre voltage sensor-based system can be formed, indirectly measure high voltage information by the electric field intensity responding to sensing module place, safety, reliable, accurate high voltage measuring monitoring means are provided.
Steeping Ke Ersi (Pockels) effect with electric light is basic sensing principle, determines the stability dependency of this optical fiber sensing system in fiber optic conduction polarisation of light characteristic, very sensitive for fiber optic conduction polarisation of light characteristic variations.Any point place on the light wave conducting path of optical fiber, executes mechanical vibration or variation of ambient temperature etc. outward, all by changing the change of light conducting polarization state, causes this optical fiber sensing system inevitably to become a time-varying system.
Refer to shown in Fig. 2, optical-fibre voltage sensor-based system comprise be placed in Control of Power Plant indoor control module, be placed in the sensing module under tested high voltage environment and isolation optical cable both connecting, because isolation optical cable and sensing module are insulator, effective light isolated insulation can be carried out in the secondary low-voltage loop at of sensing module place time high tension loop and control module place, ensure that secondary low-voltage loop and the safety of personnel under high tension loop abnormal conditions; Owing to adopting pure optical measurement principle, light source is in control module, and powers without the need to source power supply at sensing module place, measures the impact that the voltage waveform obtained is not subject to strong electromagnetic; Because electro-optic crystal response band is wide, it not only can be used for measuring direct voltage component, also can the higher harmonic component of measuring voltage, even superpotential transient-wave.The high voltage waveform measuring instrument that this principle makes, is expected to the static voltage table that replacement high voltage laboratory generally uses, peak-reading voltmeter and voltage divider etc.
Fig. 3 is the basic light path composition of optical fiber sensing system, this optical fiber sensing system comprises light source, polarizer P, phase modulation component M, isolation optical fiber S, bubble Ke Ersi element V, analyzer A, optical fiber sensing system is separated into two pieces of substrates by isolation optical fiber S, one piece of modulation module be made up of polarizer P, phase modulation component M, another block is by the sensing module steeping Ke Ersi element V, analyzer A forms, and modulation module, sensing module can be carried out the isolation of remote space by isolation optical fiber S; Polarizer P is by its light transmission shaft orientation ψ
pdescribe, phase modulation component M is by its fast axis orientation ψ
mwith produced phase differential or phase delay θ
mdescribe, isolation optical fiber S is by the fast axis orientation ψ of its entrance port
s1, optical fiber gross phase postpone θ
sand the fast axis orientation ψ of exit portal
s2describe, bubble Ke Ersi element V is by its fast axis orientation ψ
vwith produced phase differential or phase delay θ
vdescribe, analyzer A is by its light transmission shaft orientation ψ
adescribe.
As shown in Figure 4, described control module comprises light source, phase-modulator, modulation voltage generator, photoelectric commutator, digital to analog converter, signal processor, described light source is connected with the input end of described phase-modulator by the connector C1 of optical fiber, the output terminal of described phase-modulator is connected in described isolation optical cable by the connector C2 of optical fiber, described modulation voltage generator is connected to described phase-modulator, isolation outgoing optical fiber in described isolation optical cable is all connected with described photoelectric commutator, described photoelectric commutator is connected to described signal processor via described digital to analog converter, processed by the light intensity signal of described signal processor to isolation outgoing optical fiber and calculated, extract the information of tested voltage.
As shown in Figure 5, described sensing module comprises the first optical fiber collimator 1, second optical fiber collimator 2, the 3rd optical fiber collimator 3, the 4th optical fiber collimator 4, first beam splitter 5, second beam splitter 6, bubble Ke Ersi element 7, first analyzer 8, second analyzer 9, the 3rd analyzer 10,1/4 wavelength plate 11;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator 1, the output terminal of described first optical fiber collimator 1 transmits light to described first beam splitter 5, by described first beam splitter 5, light is divided into two-way, wherein a road light transfers to described bubble Ke Ersi element 7 successively, described first analyzer 8, the input end of described second optical fiber collimator 2, its another road optical transport is to described second beam splitter 6, by described second beam splitter 6, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate 11 successively, described second analyzer 9, the input end of described 3rd optical fiber collimator 3, its another road light transfers to described 3rd analyzer 10 successively, the input end of described 4th optical fiber collimator 4, the output terminal of described second optical fiber collimator 2, the output terminal of described 3rd optical fiber collimator 3, the output terminal of described 4th optical fiber collimator 4 is all by Fiber connection to described isolation optical cable.
As shown in Figure 6, described sensing module comprises the first optical fiber collimator 1, second optical fiber collimator 2, the 3rd optical fiber collimator 3, the 4th optical fiber collimator 4, first beam splitter 5, second beam splitter 6, bubble Ke Ersi element 7, first analyzer 8, second analyzer 9, the 3rd analyzer 10,1/4 wavelength plate 11;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator 1, the output terminal of described first optical fiber collimator 1 transmits light to described first beam splitter 5, by described first beam splitter 5, light is divided into two-way, wherein a road light transfers to described second analyzer 9 successively, the input end of described 3rd optical fiber collimator 3, its another road light transfers to described bubble Ke Ersi element 7 successively, described second beam splitter 6, by described second beam splitter 6, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate 11 successively, described 3rd analyzer 10, the input end of described 4th optical fiber collimator 4, its another road light transfers to described first analyzer 8 successively, the input end of described second optical fiber collimator 2, the output terminal of described second optical fiber collimator 2, the output terminal of described 3rd optical fiber collimator 3, the output terminal of described 4th optical fiber collimator 4 is all by Fiber connection to described isolation optical cable.
As shown in Figure 7, described sensing module comprises the first optical fiber collimator 1, second optical fiber collimator 2, the 3rd optical fiber collimator 3, the 4th optical fiber collimator 4, first beam splitter 5, second beam splitter 6, bubble Ke Ersi element 7, first analyzer 8, second analyzer 9, the 3rd analyzer the 10, the 1 wavelength plate the 11, the 2 1/4 wavelength plate 12, the 3rd beam splitter 13, the 4th analyzer 14, the 5th optical fiber collimator 15;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator 1, the output terminal of described first optical fiber collimator 1 transmits light to described first beam splitter 5, by described first beam splitter 5, light is divided into two-way, wherein a road light is connected to described bubble Ke Ersi element 7 successively, described second beam splitter 6, by described second beam splitter 6, light is divided into two-way, wherein a road light transfers to described 2 1/4 wavelength plate 12 successively, described 3rd analyzer 10, the input end of described 4th optical fiber collimator 4, another road light sent from described second beam splitter 6 transfers to described first analyzer 8 successively, the input end of described second optical fiber collimator 2, another road optical transport sent from described first beam splitter 5 is to described 3rd beam splitter 13, by described 3rd beam splitter 13, light is divided into two-way, wherein a road light transfers to described one 1/4 wavelength plate 11 successively, described second analyzer 9, the input end of described 3rd optical fiber collimator 3, another road light sent from described 3rd beam splitter 13 transfers to described 4th analyzer 14 successively, the input end of described 5th optical fiber collimator 5, the output terminal of described second optical fiber collimator 2, the output terminal of described 3rd optical fiber collimator 3, the output terminal of described 4th optical fiber collimator 4, the output terminal of described 5th optical fiber collimator 5 is all by Fiber connection to described isolation optical cable.
Particularly, described first beam splitter 5, described second beam splitter 6, described 3rd beam splitter 13 are non-polarizing beamsplitter.
Particularly, described optical fiber is single-mode fiber.
Refer to shown in Fig. 4 to Fig. 7, optical fiber collimator is used to the incident light that outgoing isolation fiber optic conduction is come, and reception light makes it inject loopback fibre; Without polarization beam apparatus NPBS, be used to incident ray to be divided into two bundles, to form multi-pass optical system; The birefraction of bubble Ke Ersi element (crystal) light changes with electric field intensity.Being provided with in angle, the fast axis direction produced with the electric field steeping Ke Ersi element place is for reference direction, and the analyzer light transmission shaft direction of each light path is set to 45 degree; The fast axis direction of 1/4 wavelength plate is set to electroluminescent fast axis direction in the same way, corresponding light pass is entered to the phase differential of additional pi/2, makes this light path and another light path form phase differential complementary.
Embodiment one: the index path in sensing module is for 4 line structures shown in Fig. 7, and sensing module can be placed among the electric field that tested voltage produces, and also can by after tested voltage, more directly be added on the bubble Ke Ersi element in sensing module; Workflow is as shown in Fig. 8 and Fig. 9:
Obtain the method with voltage dependent phase difference, described method needs the optical-fibre voltage sensor-based system providing the invention described above, and described method specifically comprises the steps:
Step 1, start described control module power supply after, the laser sent by described light source is entered in described phase-modulator by the connector C1 of optical fiber, and then is entered in the incident optical of described isolation optical cable by the connector C2 of optical fiber;
Step 2, described modulation voltage generator is by generation one constant amplitude and have periodic stepwise voltage, is then modulated by the Signal transmissions of this voltage to described phase-modulator, voltage signal is loaded on light wave and forms light modulated;
Step 3, this light modulated transfer in the described sensing module under electric field action by the incident optical in described isolation optical cable, with information of voltage in the light path of now described sensing module, then the connector C3 of this light modulated via optical fiber is transferred in the outgoing optical fiber of described isolation optical cable, then transfer in described photoelectric commutator;
Step 4, the light intensity signal in described photoelectric commutator is converted to electric signal after, by described modulation voltage generator, sample clock pulse is controlled, then by described digital to analog converter to conversion after electric signal sample;
Step 5, obtain one group of intensity signal by sampling, then by described signal processor, process is carried out to this group intensity signal and calculate, system function, intrinsic function can be calculated, then build intrinsic function group by described intrinsic function; Specific as follows:
Step 51, the light intensity general expression sent by the outgoing optical fiber of described isolation optical cable are:
I(t)＝(1/2)γ(t)I
o(t){2α+cos2(ψ
P-ψ
M)β+sin2(ψ
P-ψ
M)η·cos[θ
M(t)]+sin2(ψ
P-ψ
M)ζ·sin[θ
M(t)]}，
And α={ [cos
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)] cos
2(ψ
s-ψ
v)
+[cos
2(ψ
P-ψ
M)sin
2(ψ
M-ψ
S)+sin
2(ψ
P-ψ
M)cos
2(ψ
M-ψ
S)]sin
2(ψ
S-ψ
V)]}cos
2(ψ
V-ψ
A)+{[cos
2(ψ
P-ψ
M)cos
2(ψ
M-ψ
S)+sin
2(ψ
P-ψ
M)sin
2(ψ
M-ψ
S)]sin
2(ψ
S-ψ
V)
+[cos
2(ψ
P-ψ
M)sin
2(ψ
M-ψ
S)+sin
2(ψ
P-ψ
M)cos
2(ψ
M-ψ
S)]cos
2(ψ
S-ψ
V)]}sin
2(ψ
V-ψ
A)
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, ψ
pthe light transmission shaft orientation representing the polarizer, ψ
mthe fast axis orientation representing phase phase modulation component, θ
mt () is the phase differential or phase delay that represent that phase phase modulation component produces, ψ
sthe fast axis orientation representing isolation optical fiber entrance port, ψ
vthe fast axis orientation representing sensing element, ψ
abe the light transmission shaft orientation representing analyzer, β, η, ζ all represent intrinsic function;
The angle in the light transmission shaft orientation of the polarizer and the fast axis orientation of phase modulation component is set to 45 degree, i.e. (ψ
p-ψ
m)=45 °, then general expression can be changed further and is kept to:
I(t)＝(1/2)γ(t)I
o(t){1+η·cos[θ
M(t)]+ζ·sin[θ
M(t)]}，
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mt () is the phase differential or phase delay that represent that phase modulation component produces, η, ζ all represent intrinsic function;
All there are three kinds of modulation conditions each modulation period, are respectively θ
m(t)=+ θ
m, θ
m(t)=0, θ
m(t)=-θ
m, then its one group of intensity signal { I obtained that samples
+, I
0, I
-be respectively:
I
+(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]+ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
I
0(t)=(1/2) γ (t) I
ot () { 1+ η }, wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, η represents intrinsic function;
I
-(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]-ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
Step 52, the light intensity signal { I obtained by sampling
+, I
0, I
-, the system function I calculated
m, intrinsic function ζ and η be respectively:
I
m=[I
+(t)+I
-(t)-2I
0(t) cos (θ
m)]/tan (θ
m/ 2), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition;
ζ=[I
+(t) – I
-(t)]/I
m(t), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
mt () represents system function;
η={ 2I
0(t)-[I
+(t)+I
-(t)] }/{ I
m(t) tan [θ
m/ 2] }, in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition, I
mt () represents system function;
Wherein, system function I
mt () is defined by following formula: I
m(t)=γ (t) I
o(t) sin [θ
m];
Intrinsic function ζ and η is having based on during described sensing module:
ζ=ζ
tcos2 (ψ
v-ψ
a)+ζ
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
ζ
t=sin2 (ψ
s2-ψ
v) sin (θ
s), ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
η=η
tcos2 (ψ
v-ψ
a)+η
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
η
T＝-sin2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)-cos2(ψ
M-ψ
S1)sin2(ψ
S2-ψ
V)·cos(θ
S)，
η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)
·cos(θ
V)cos(θ
S)+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 53, the angle between the fast axis direction of bubble Ke Ersi element and the light transmission shaft direction of analyzer is set to 45 degree, i.e. (ψ
v-ψ
a)=45 °, so intrinsic function ζ and η becomes respectively:
ζ=ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
s2the fast axis orientation representing isolation fiber exit mouth, ψ
vthe fast axis orientation representing sensing element, θ
srepresent that isolation optical fiber gross phase postpones, θ
vthe phase differential or phase delay that represent that sensing element produces;
η＝η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)
-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)·cos(θ
V)cos(θ
S)
+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 54, get ζ
rS=cos2 (ψ
s2-ψ
v) sin (θ
s)=Ksin (Θ) and ζ
r4=cos (θ
s)=Kcos (Θ), so ζ
r=Ksin (Θ+θ
v) and tan (Θ)=ζ
rS/ ζ
r4=cos2 (ψ
s2-ψ
v) tan (θ
s);
Wherein, Θ is that the equivalent phase introduced by isolation optical fiber is poor, and it is by external force, as mechanical vibration or variation of ambient temperature etc. act on the path of isolation optical fiber, is formed, have time-varying characteristics through accumulation; ψ
vthe fast axis orientation representing sensing element, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
sbe represent that isolation optical fiber gross phase postpones, K is the coefficient of light path;
The structure of the light path of step 55, sensing module is the intrinsic function ζ relative to basic light path
rT=Ksin (Θ+θ
v), another road light path can be built, make the intrinsic function of its light path be ζ
rR=Kcos (Θ+θ
v), there is the intrinsic function group { ζ on following 4 tunnels
rT, ζ
rR, ζ
rS, ζ
r4or { η
rT, η
rR, η
rS, η
r4}:
ζ
rT=Ksin (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rR=Kcos (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rS=Ksin (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
ζ
r4=Kcos (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
η
rT=Msin (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rR=Mcos (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rS=Msin (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing;
η
r4=Mcos (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing.
Table 1 is the combination of intrinsic function and light path and electroluminescent phase differential θ
vmeasurement range, shown in table specific as follows:
Table 1:
| Light path number | Electroluminescent phase differential θ VMeasurement range | Intrinsic function ζ | Intrinsic function η |
| 3 tunnels | [-π/2,π/2] | ζ RT、ζ RS、ζ R4、 | η RT、η RS、η R4、 |
| 3 tunnels | [-π/2,π/2] | ζ RT、ζ RR、ζ RS | η RT、η RR、η RS |
| 4 tunnels | [-π,π] | ζ RT、ζ RR、ζ RS、ζ R4 | η RT、η RR、η RS、η R4 |
Step 6, by this intrinsic function group, calculate total phase differential (Θ+θ of described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ;
Step 7, total phase differential (Θ+θ by described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ, calculate the electroluminescent phase differential θ with voltage in proportion
v.
Embodiment two: the index path in sensing module is for 3 line structures shown in Fig. 5, and its syndeton and principle of work can consider and examine embodiment one.
Embodiment three: the index path in sensing module is for 3 line structures shown in Fig. 6, and its syndeton and principle of work can consider and examine embodiment one.
Although the foregoing describe the specific embodiment of the present invention; but be familiar with those skilled in the art to be to be understood that; specific embodiment described by us is illustrative; instead of for the restriction to scope of the present invention; those of ordinary skill in the art, in the modification of the equivalence done according to spirit of the present invention and change, should be encompassed in scope that claim of the present invention protects.
Claims (9)
1. an optical-fibre voltage sensor-based system, is characterized in that: comprise control module, sensing module and isolation optical cable, described isolation optical cable is connected with described control module, described sensing module respectively.
2. a kind of optical-fibre voltage sensor-based system as claimed in claim 1, is characterized in that: described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, 1/4 wavelength plate;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light transfers to described bubble Ke Ersi element successively, described first analyzer, the input end of described second optical fiber collimator, its another road optical transport is to described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate successively, described second analyzer, the input end of described 3rd optical fiber collimator, its another road light transfers to described 3rd analyzer successively, the input end of described 4th optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator is all by Fiber connection to described isolation optical cable.
3. a kind of optical-fibre voltage sensor-based system as claimed in claim 1, is characterized in that: described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, 1/4 wavelength plate;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light transfers to described second analyzer successively, the input end of described 3rd optical fiber collimator, its another road light transfers to described bubble Ke Ersi element successively, described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 1/4 wavelength plate successively, described 3rd analyzer, the input end of described 4th optical fiber collimator, its another road light transfers to described first analyzer successively, the input end of described second optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator is all by Fiber connection to described isolation optical cable.
4. a kind of optical-fibre voltage sensor-based system as claimed in claim 1, is characterized in that: described sensing module comprises the first optical fiber collimator, the second optical fiber collimator, the 3rd optical fiber collimator, the 4th optical fiber collimator, the first beam splitter, the second beam splitter, bubble Ke Ersi element, the first analyzer, the second analyzer, the 3rd analyzer, the one 1/4 wavelength plate, the 2 1/4 wavelength plate, the 3rd beam splitter, the 4th analyzer, the 5th optical fiber collimator;
Isolation incident optical in described isolation optical cable is connected with the input end of described first optical fiber collimator, the output terminal of described first optical fiber collimator transmits light to described first beam splitter, by described first beam splitter, light is divided into two-way, wherein a road light is connected to described bubble Ke Ersi element successively, described second beam splitter, by described second beam splitter, light is divided into two-way, wherein a road light transfers to described 2 1/4 wavelength plate successively, described 3rd analyzer, the input end of described 4th optical fiber collimator, another road light sent from described second beam splitter transfers to described first analyzer successively, the input end of described second optical fiber collimator, another road optical transport sent from described first beam splitter is to described 3rd beam splitter, by described 3rd beam splitter, light is divided into two-way, wherein a road light transfers to described one 1/4 wavelength plate successively, described second analyzer, the input end of described 3rd optical fiber collimator, another road light sent from described 3rd beam splitter transfers to described 4th analyzer successively, the input end of described 5th optical fiber collimator, the output terminal of described second optical fiber collimator, the output terminal of described 3rd optical fiber collimator, the output terminal of described 4th optical fiber collimator, the output terminal of described 5th optical fiber collimator is all by Fiber connection to described isolation optical cable.
5. a kind of optical-fibre voltage sensor-based system as claimed in claim 1, it is characterized in that: described control module comprises light source, phase-modulator, modulation voltage generator, photoelectric commutator, digital to analog converter, signal processor, described light source is connected with the input end of described phase-modulator by the connector C1 of optical fiber, the output terminal of described phase-modulator is connected in described isolation optical cable by the connector C2 of optical fiber, described modulation voltage generator is connected to described phase-modulator, isolation outgoing optical fiber in described isolation optical cable is all connected with described photoelectric commutator, described photoelectric commutator is connected to described signal processor via described digital to analog converter.
6. a kind of optical-fibre voltage sensor-based system as claimed in claim 4, is characterized in that: described first beam splitter, described second beam splitter, described 3rd beam splitter are non-polarizing beamsplitter.
7. a kind of optical-fibre voltage sensor-based system as claimed in claim 5, is characterized in that: described optical fiber is single-mode fiber.
8. obtain the method with voltage dependent phase difference, it is characterized in that: described method needs to provide optical-fibre voltage sensor-based system as claimed in claim 1, and described method specifically comprises the steps:
Step 1, start described control module power supply after, the laser sent by described light source is entered in described phase-modulator by optical fiber, and then enters in the incident optical of described isolation optical cable;
Step 2, described modulation voltage generator is by generation one constant amplitude and have periodic stepwise voltage, is then modulated by the Signal transmissions of this voltage to described phase-modulator, modulated voltage signal is loaded on light wave and forms light modulated;
Step 3, this light modulated transfer in the described sensing module under electric field action by the incident optical in described isolation optical cable, with tested information of voltage in the light path of now described sensing module, then this light modulated is transferred in the outgoing optical fiber of described isolation optical cable, then transfer in described photoelectric commutator;
Step 4, the light intensity signal in described photoelectric commutator is converted to electric signal after, by described modulation voltage generator, sample clock pulse is controlled, then by described digital to analog converter to conversion after electric signal sample;
Step 5, obtain one group of intensity signal by sampling, then by described signal processor, process is carried out to this group intensity signal and calculate, system function, intrinsic function can be calculated, then build intrinsic function group by described intrinsic function;
Step 6, by this intrinsic function group, calculate total phase differential (Θ+θ of described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ;
Step 7, total phase differential (Θ+θ by described optical-fibre voltage sensor-based system
v) and isolation optical fiber equivalent phase difference Θ, calculate the electroluminescent phase differential θ with voltage in proportion
v.
9. a kind ofly as claimed in claim 8 obtain the method for measured value by optical-fibre voltage sensor-based system, it is characterized in that: described step 5 is specific as follows:
Step 51, the light intensity general expression sent by the outgoing optical fiber of described isolation optical cable are:
I(t)＝(1/2)γ(t)I
o(t){2α+cos2(ψ
P-ψ
M)β+sin2(ψ
P-ψ
M)η·cos[θ
M(t)]+sin2(ψ
P-ψ
M)ζ·sin[θ
M(t)]}，
And α={ [cos
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)] cos
2(ψ
s-ψ
v)+[cos
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)] sin
2(ψ
s-ψ
v)] cos
2(ψ
v-ψ
a)+{ [cos
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)] sin
2(ψ
s-ψ
v)+[cos
2(ψ
p-ψ
m) sin
2(ψ
m-ψ
s)+sin
2(ψ
p-ψ
m) cos
2(ψ
m-ψ
s)] cos
2(ψ
s-ψ
v)] sin
2(ψ
v-ψ
a)
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, ψ
pthe light transmission shaft orientation representing the polarizer, ψ
mthe fast axis orientation representing phase modulation component, θ
mt () is the phase differential or phase delay that represent that phase modulation component produces, ψ
sthe fast axis orientation representing isolation optical fiber entrance port, ψ
vthe fast axis orientation representing sensing element, ψ
abe the light transmission shaft orientation representing analyzer, β, η, ζ all represent intrinsic function;
The angle in the light transmission shaft orientation of the polarizer and the fast axis orientation of phase modulation component is set to 45 degree, i.e. (ψ
p-ψ
m)=45 °, then general expression can be changed further and is kept to:
I(t)＝(1/2)γ(t)I
o(t){1+η·cos[θ
M(t)]+ζ·sin[θ
M(t)]}，
Wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mt () is the phase differential or phase delay that represent that phase modulation component produces, η, ζ all represent intrinsic function;
All there are three kinds of modulation conditions each modulation period, are respectively θ
m(t)=+ θ
m, θ
m(t)=0, θ
m(t)=-θ
m, then its one group of intensity signal { I obtained that samples
+, I
0, I
-be respectively:
I
+(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]+ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
I
0(t)=(1/2) γ (t) I
ot () { 1+ η }, wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, η represents intrinsic function;
I
-(t)=(1/2) γ (t) I
o(t) { 1+ η cos [θ
m]-ζ sin [θ
m], wherein, γ (t) is the total effect of the transmissivity of each unit to light, I
ot () is the light intensity that light source sends, θ
mbe the modulation numerical value represented under phase modulation component modulation condition, η, ζ all represent intrinsic function;
Step 52, the light intensity signal { I obtained by sampling
+, I
0, I
-, the system function I calculated
m, intrinsic function ζ and η be respectively:
I
m=[I
+(t)+I
-(t)-2I
0(t) cos (θ
m)]/tan (θ
m/ 2), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition;
ζ=[I
+(t) – I
-(t)]/I
m(t), in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
mt () represents system function;
η={ 2I
0(t)-[I
+(t)+I
-(t)] }/{ I
m(t) tan [θ
m/ 2] }, in formula, I
+t () represents that modulation condition is θ
m(t)=+ θ
munder intensity signal, I
-t () represents that modulation condition is θ
m(t)=-θ
munder intensity signal, I
0t () represents that modulation condition is θ
mintensity signal under (t)=0, θ
mthe modulation numerical value represented under phase modulation component modulation condition, I
mt () represents system function;
Wherein, system function I
mt () is defined by following formula: I
m(t)=γ (t) I
o(t) sin [θ
m];
Intrinsic function ζ and η is having based on during described sensing module:
ζ=ζ
tcos2 (ψ
v-ψ
a)+ζ
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
ζ
t=sin2 (ψ
s2-ψ
v) sin (θ
s), ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
η=η
tcos2 (ψ
v-ψ
a)+η
rsin2 (ψ
v-ψ
a), wherein, have when polarization counts three rank:
η
T＝-sin2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)-cos2(ψ
M-ψ
S1)sin2(ψ
S2-ψ
V)·cos(θ
S)，
η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)
·cos(θ
V)cos(θ
S)+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
athe light transmission shaft orientation representing analyzer, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 53, the angle between the fast axis direction of sensing element and the light transmission shaft direction of analyzer is set to 45 degree, i.e. (ψ
v-ψ
a)=45 °, so intrinsic function ζ and η becomes respectively:
ζ=ζ
r=cos2 (ψ
s2-ψ
v) sin (θ
s) cos (θ
v)+cos (θ
s) sin (θ
v), in formula, ψ
s2the fast axis orientation representing isolation fiber exit mouth, ψ
vthe fast axis orientation representing sensing element, θ
srepresent that isolation optical fiber gross phase postpones, θ
vthe phase differential or phase delay that represent that sensing element produces;
η＝η
R＝+sin 2(ψ
M-ψ
S1)sin 2(ψ
S2-ψ
V)·cos(θ
V)
-cos2(ψ
M-ψ
S1)cos2(ψ
S2-ψ
V)·cos(θ
V)cos(θ
S)
+cos2(ψ
M-ψ
S1)·1·sin(θ
V)sin(θ
S)，
In formula, ψ
vthe fast axis orientation representing sensing element, ψ
mthe fast axis orientation representing phase modulation component, ψ
s1the fast axis orientation representing isolation optical fiber entrance port, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
srepresent that isolation optical fiber gross phase postpones;
Step 54, get ζ
rS=cos2 (ψ
s2-ψ
v) sin (θ
s)=Ksin (Θ) and ζ
r4=cos (θ
s)=Kcos (Θ), so ζ
r=Ksin (Θ+θ
v) and tan (Θ)=ζ
rS/ ζ
r4=cos2 (ψ
s2-ψ
v) tan (θ
s);
Wherein, Θ is that the equivalent phase introduced by isolation optical fiber is poor, and it is by external force, as mechanical vibration or variation of ambient temperature etc. act on the path of isolation optical fiber, is formed, have time-varying characteristics through accumulation; ψ
vthe fast axis orientation representing sensing element, ψ
s2the fast axis orientation representing isolation fiber exit mouth, θ
vthe phase differential or phase delay that represent that sensing element produces, θ
sbe represent that isolation optical fiber gross phase postpones, K is the coefficient of light path;
The structure of the light path of step 55, sensing module is the intrinsic function ζ relative to basic light path
rT=Ksin (Θ+θ
v), another road light path can be built, make the intrinsic function of its light path be ζ
rR=Kcos (Θ+θ
v), there is the intrinsic function group { ζ on following 4 tunnels
rT, ζ
rR, ζ
rS, ζ
r4or { η
rT, η
rR, η
rS, η
r4}:
ζ
rT=Ksin (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rR=Kcos (Θ+θ
v), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor, θ
vthe phase differential or phase delay that represent that sensing element produces;
ζ
rS=Ksin (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
ζ
r4=Kcos (Θ), in formula, K is the coefficient of light path, and Θ is that the equivalent phase introduced by isolation optical fiber is poor;
η
rT=Msin (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rR=Mcos (θ
η+ θ
v), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing, θ
vthe phase differential or phase delay that represent that sensing element produces;
η
rS=Msin (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing;
η
r4=Mcos (θ
η), in formula, M is the coefficient of light path, θ
ηpoor by the equivalent phase of isolation optical fiber introducing.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117930502A (en) * | 2024-03-21 | 2024-04-26 | 上海频准激光科技有限公司 | Amplitude control system based on phase shift |
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