CN103245817A - Voltage measuring method and voltage transducer - Google Patents

Abstract

A voltage transducer adopts the structure that light emitted by a light source sequentially passes through a first collimating device, a polarizer, a lambda/4 wave plate, a sensitive optical crystal and an analyzer, wherein the light emitted by the analyzer respectively passes through a second collimating device and a first photoelectric detector; the light emitted by a third collimating device, a second photoelectric detector and the first photoelectric detector and light emitted from the second photoelectric detector respectively are input into a signal processing unit; and the signal processing unit outputs driving signals to the light source. The voltage transducer further comprises a modulation electrode and a ground electrode, which are arranged on the sensitive optical crystal side and connected with the signal processing unit. The invention further provides a voltage measuring method. Due to the adoption of the embodiment of the invention, the measurement accuracy of the DC and AC can be ensured.

Description

A kind of method of measuring voltage and voltage sensor

Technical field

The application relates to the photoelectricity test technical field, more specifically, relates to a kind of method and voltage sensor of measuring voltage.

Background technology

Electric power is traction and the basis of social development, and the safety of electric system is most important to socio-economic development and national security.Electric current and voltage are two basic parameters of electric system, all need electric current, voltage are accurately measured in the every field of generating, power transmission and distribution, electricity consumption.

Voltage sensor can be realized the measurement to voltage; for relay protection, electric energy metrical and power network monitoring provide basic data; be the nucleus equipment of electric power network, its reliability, security, long-time stability are directly related with safety, the stable operation of electric system.

The method of traditional measurement high pressure comprises that electromagnetic potential sensor, resitstance voltage divider, capacitive divider and Hall voltage sensor etc. are multiple, and wherein electromagnetic potential sensor and capacitive divided voltage mutual inductor have obtained widespread use in electric system.

But along with the raising of voltage class of electric power system and the increase of capacity, what measurement and protection required improves constantly, and its weak point becomes increasingly conspicuous, and mainly shows as:

(1), the insulation difficulty big, make the out-of-proportion raising of volume, weight and price of mutual inductor because of insulation.

(2), intrinsic magnetic saturation, the dynamic range of transformer iron core structure is little, frequency band is narrow.

(3), the secondary output signal can not directly and digitizing be measured and the protection equipment interface.

(4), the capacitive divided voltage mutual inductor easily produces ferroresonance.

Novel optical voltage transformer (VT) based on bubble Ke Ersi (Pockels) electrooptical effect has natural photoelectricity isolation " non-intervention type " measurement advantage; series of advantages such as electric insulating quality is good, antijamming capability is strong, response speed is fast, volume is little, in light weight and safe and reliable; and be convenient to and optical fiber communication, computer system networking; form complete monitoring, control and protecting network; very wide application prospect is arranged in electric system, become the technique direction of voltage sensor development.

Existing optical voltage sensor adopts double light path detection technique scheme more, can reduce the error that the light source power instability is brought preferably.Just can calculate voltage by the caused light phase of tested alternating voltage.

Voltage transformer (VT) double light path output intensity is expressed as respectively:

I _o+＝K ₁I _i(1+δ) （1）

I _o-＝K ₂I _i(1-δ) （2）

Wherein, K ₁, K ₂Be respectively the gain of two-way light path, I _iBe the input light intensity, δ is the caused light phase of tested alternating voltage.Be zero to be that δ is zero when tested alternating voltage, DC component is only arranged.The light intensity of DC component is respectively in the two-way light intensity:

$I_{o+}^{\mathrm{dc}}=K_1{I}_i---\left(3\right)$

$I_{o-}^{\mathrm{dc}}=K_2{I}_i---\left(4\right)$

Then got by (1)～(4) formula:

$\mathrm{\δ}=\frac{\frac{I_{o+}}{I_{o+}^{\mathrm{dc}}}-\frac{I_{o-}}{I_{o-}^{\mathrm{dc}}}}{2}---\left(5\right)$

Have following technical matters in the prior art, contain DC component in measured signal, the degree of accuracy of δ is lower, calculates measuring voltage by δ again, then further can't guarantee the accuracy of measuring voltage.

Summary of the invention

The embodiment of the invention proposes a kind of method of measuring voltage, can guarantee the accuracy of voltage measurement.

The embodiment of the invention also proposes a kind of voltage sensor, can guarantee the accuracy of voltage measurement.

The technical scheme of the embodiment of the invention is as follows:

A kind of voltage sensor, emergent light in the light source is in proper order by first collimating apparatus, the polarizer, λ/4 wave plates, responsive optical crystal and analyzer, the emergent light of analyzer is respectively by second collimating apparatus, first photodetector, and the 3rd collimating apparatus, second photodetector, the emergent light of the emergent light of first photodetector and second photodetector is input to signal processing unit respectively, signal processing unit is to the light source output drive signal, described voltage sensor also comprises: modulator electrode and ground electrode

Modulator electrode and ground electrode all place responsive optical crystal side, and modulator electrode connects signal processing unit, and ground electrode connects signal processing unit.

The voltage of described modulator electrode comprises square-wave frequency modulation voltage.

The frequency of described square-wave frequency modulation voltage is at least 10 times of tested electric voltage frequency.

Described modulator electrode comprises first modulator electrode and second modulator electrode, and first modulator electrode and second modulator electrode are positioned at the left and right sides of responsive optical crystal, and ground electrode is positioned at the downside of responsive optical crystal.

Described modulator electrode and described ground electrode all are positioned at the downside of described responsive optical crystal, and described ground electrode is below described modulator electrode.

A kind of method of measuring voltage, described method comprises:

Responsive optical crystal is applied the forward modulation voltage, in first light path, obtain first light intensity, in second light path, obtain the 3rd light intensity;

Responsive optical crystal is applied the negative sense modulation voltage, in first light path, obtain second light intensity, in second light path, obtain the 4th light intensity;

Calculate the phase differential of tested electric field correspondence and tested voltage according to first light intensity, second light intensity, the 3rd light intensity and the 4th light intensity.

Described modulation voltage comprises square-wave frequency modulation voltage.

The frequency of described square-wave frequency modulation voltage is at least 10 times of tested electric voltage frequency.

From technique scheme, as can be seen, in embodiments of the present invention responsive optical crystal is applied the forward modulation voltage, in first light path, obtain first light intensity, in second light path, obtain the 3rd light intensity; Responsive optical crystal is applied the negative sense modulation voltage, in first light path, obtain second light intensity, in second light path, obtain the 4th light intensity; Calculate the phase differential of tested electric field correspondence and measuring voltage according to first light intensity, second light intensity, the 3rd light intensity and the 4th light intensity.Because responsive optical crystal is applied modulation voltage, according to first light intensity that obtains, second light intensity, the 3rd light intensity and the 4th light intensity phase differential in the tested electric field correspondence of calculating, direct current signal in its computation process and the measured signal is irrelevant, therefore can improve the degree of accuracy of light phase, the further accuracy of measuring voltage.

Description of drawings

Fig. 1 is the structural representation of voltage sensor;

Fig. 2 is the method flow synoptic diagram of measuring voltage;

Fig. 3 is the sampling time sequence figure of first detector;

Fig. 4 is the sampling time sequence figure of second detector;

Fig. 5 is modulator electrode position view among the embodiment one;

Fig. 6 is modulator electrode position view among the embodiment two.

Embodiment

For making the purpose, technical solutions and advantages of the present invention express clearlyer, the present invention is further described in more detail below in conjunction with drawings and the specific embodiments.

In embodiments of the present invention, by responsive optical crystal is applied modulation voltage, in the process of calculating phasic difference, be not subjected to whether existing the influence of DC current, thereby guaranteed the degree of accuracy of phasic difference, and then guaranteed the accuracy of tested voltage.

Be the structural representation of voltage sensor referring to accompanying drawing 1, the emergent light in the light source is in proper order by first collimating apparatus, the polarizer, λ/4 wave plates, responsive optical crystal and analyzer, and the emergent light of analyzer is by second collimating apparatus, first photodetector; The emergent light of analyzer is by the 3rd collimating apparatus, second photodetector.

The output twin shaft of analyzer is connected with first photodetector, second photodetector through collimating apparatus, single-mode fiber respectively.Light path via first photodetector is called first light path, is called second light path via the light path of second photodetector.First photodetector after second photodetector carries out opto-electronic conversion, transfers digital signal respectively to after being input to signal processing unit, and signal processing unit is to the size of light source outputting drive voltage value after calculation process.

At responsive optical crystal side modulator electrode and ground electrode are arranged, the voltage between modulator electrode and the ground electrode is applied on the responsive optical crystal and causes phasic difference.Wherein, modulator electrode connects signal processing unit, and ground electrode connects signal processing unit.

Participating in accompanying drawing 2 is method flow synoptic diagram of measuring voltage, specifically may further comprise the steps:

201, responsive optical crystal is applied the forward modulation voltage, in first light path, obtain first light intensity, in second light path, obtain the 3rd light intensity; Responsive optical crystal is applied the negative sense modulation voltage, in first light path, obtain second light intensity, in second light path, obtain the 4th light intensity.

The light intensity that first photodetector and second photodetector detect is respectively:

I _o+＝K ₁I _i(1+δ) （6）

I _o-＝K ₂I _i(1-δ) （7）

Wherein, K ₁, K ₂Be respectively the gain of two-way light path, I _iBe the input light intensity, δ is for applying the caused light phase of voltage.δ is produced by tested electric field and modulated electric fields stack.When the voltage of modulator electrode is square-wave frequency modulation voltage, namely

δ＝δ _E±δ _Ud （8）

δ _EBe the phase differential that tested electric field produces, δ _UdPhase differential for the modulated electric fields generation.Modulation voltage adopts square-wave frequency modulation.Square wave frequency is at least 10 times of tested electric voltage frequency.For example can be taken as 20kHz, square wave generating positive and negative voltage amplitude equates.Certainly, also can adopt sine wave modulation voltage, the cosine wave (CW) modulation voltage is modulated.This moment, δ was produced by tested electric field and modulated electric fields stack, and the relation of the phase differential that δ and modulated electric fields produce not is shown in (8), but need change accordingly according to modulation voltage, and concrete computation process repeats no more.

Under the modulation of square wave electric field, shown in the sampling time sequence accompanying drawing 3 of the first photodetector electric signal, in the recurrence interval of CLK, repeatedly to sample, sampled data averages processing, can effectively reduce optical noise.The sample numerical value of 3 positive square waves of accompanying drawing and losing side ripple is respectively D1, D2, can be expressed as:

${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00003009082900021.png,HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_1=I_{o+}^1=K_1{I}_i(1+{\mathrm{\&delta;}}_E+{\mathrm{\&delta;}}_{\mathrm{Ud}})---\left(9\right)$

${\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_2=I_{o+}^2=K_1{I}_i(1+{\mathrm{\&delta;}}_E-{\mathrm{\&delta;}}_{\mathrm{Ud}})---\left(10\right)$

Under this square wave electric field modulation, shown in the sampling time sequence accompanying drawing 4 of the second photodetector electric signal, then the sample numerical value of positive square wave and losing side ripple is respectively D3, D4, can be expressed as:

$D_3=I_{o-}^1=K_2{I}_i(1-{\mathrm{\&delta;}}_E-{\mathrm{\&delta;}}_{\mathrm{Ud}})---\left(11\right)$

$D_4=I_{o-}^2=K_2{I}_i(1-{\mathrm{\&delta;}}_E+{\mathrm{\&delta;}}_{\mathrm{Ud}})---\left(12\right)$

202, (D1～D4) calculates the phase differential of tested electric field correspondence, and tested voltage according to the sampled value of first light intensity, second light intensity, the 3rd light intensity and the 4th light intensity.

Can be got by formula (9) (10) (11) (12) so:

$D_1-{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_2=I_{o+}^1-I_{o+}^2={2K}_1{I}_i{\mathrm{\&delta;}}_{\mathrm{Ud}}---\left(13\right)$

${\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00003009082900021.png,HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_2=I_{o+}^1+I_{o+}^2={2K}_1{I}_i(1+{\mathrm{\&delta;}}_E)---\left(14\right)$

$D_3-D_4=I_{o-}^1-I_{o-}^2={-2K}_2{I}_i{\mathrm{\&delta;}}_{\mathrm{Ud}}---\left(15\right)$

$D_3+D_4=I_{o-}^1+I_{o-}^2={2K}_2{I}_i(1-{\mathrm{\&delta;}}_E)---\left(16\right)$

Can be got by formula (13) (14) (15) (16):

(D ₁-D ₂)(D ₃+D ₄)＝4K ₁K ₂I _i ²δ _Ud(1-δ _E)＝K(1-δ _E) （17）

(D ₁+D ₂)(D ₃-D ₄)＝-4K ₁K ₂I _i ²δ _Ud(1+δ _E)＝-K(1+δ _E) （18）

So calculate δ _EFor

${\mathrm{\&delta;}}_E=\frac{({\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00003009082900021.png,HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_1+D_2)(D_3-D_4)+(D_1-D_2)(D_3+D_4)}{({\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA00003009082900021.png,HDA00003009082900022.png"\; state="\{\{state\}\}">D</figure-callout>}}_1+D_2)(D_3-D_4)-(D_1-D_2)(D_3+D_4)}=\frac{D_1{D}_3-D_2{D}_4}{D_2{D}_3-D_1{D}_4}---\left(19\right)$

By (19) formula as can be known, with respect to modulating frequency (being generally more than the 20kHz), tested electric field signal (interchange, direct current or higher hamonic wave signal) is low frequency signal, by high frequency modulated demodulation of the present invention, realizes δ _EResult of calculation and its composition irrelevant, measure when therefore can realize alternating current-direct current, guaranteed the accuracy of voltage measurement.

In addition, applying of modulator electrode can vertical tested electric field or parallel tested electric field, two kinds of final electric field modulation effect unanimities that realize of scheme.

Namely apply voltage perpendicular to tested electric field at modulator electrode referring to accompanying drawing 5 for embodiment one, modulator electrode comprises first modulator electrode and second modulator electrode, first modulator electrode and second modulator electrode are arranged at the both sides of responsive optical crystal respectively, and ground electrode is positioned at the downside of responsive optical crystal.First modulator electrode, second modulator electrode and ground electrode are connected with signal processing unit respectively.

Namely apply the voltage that is parallel to tested electric field at modulator electrode referring to accompanying drawing 6 for embodiment two, modulator electrode is positioned at the downside of responsive optical crystal, and ground electrode is positioned at the downside of modulator electrode, separates by the thin insulating plate between modulator electrode and the ground electrode.Modulator electrode is connected with signal processing unit respectively with ground electrode.

The above is preferred embodiment of the present invention only, is not for limiting protection scope of the present invention.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1. voltage sensor, emergent light in the light source is in proper order by first collimating apparatus, the polarizer, λ/4 wave plates, responsive optical crystal and analyzer, the emergent light of analyzer is respectively by second collimating apparatus, first photodetector, and the 3rd collimating apparatus, second photodetector, the emergent light of the emergent light of first photodetector and second photodetector is input to signal processing unit respectively, signal processing unit is to the light source output drive signal, it is characterized in that, described voltage sensor also comprises: modulator electrode and ground electrode

Modulator electrode and ground electrode all place responsive optical crystal side, and modulator electrode connects signal processing unit, and ground electrode connects signal processing unit.

2. according to the described voltage sensor of claim 1, it is characterized in that the voltage of described modulator electrode comprises square-wave frequency modulation voltage.

3. according to the described voltage sensor of claim 2, it is characterized in that the frequency of described square-wave frequency modulation voltage is at least 10 times of tested electric voltage frequency.

4. according to the described voltage sensor of claim 1, it is characterized in that, described modulator electrode comprises first modulator electrode and second modulator electrode, and first modulator electrode and second modulator electrode are positioned at the left and right sides of responsive optical crystal, and ground electrode is positioned at the downside of responsive optical crystal.

5. according to the described voltage sensor of claim 1, it is characterized in that described modulator electrode and described ground electrode all are positioned at the downside of described responsive optical crystal, described ground electrode is below described modulator electrode.

6. the method for a measuring voltage is characterized in that, described method comprises:

Responsive optical crystal is applied the forward modulation voltage, in first light path, obtain first light intensity, in second light path, obtain the 3rd light intensity;

Responsive optical crystal is applied the negative sense modulation voltage, in first light path, obtain second light intensity, in second light path, obtain the 4th light intensity;

Calculate the phase differential of tested electric field correspondence and tested voltage according to first light intensity, second light intensity, the 3rd light intensity and the 4th light intensity.

7. according to the method for the described measuring voltage of claim 6, it is characterized in that described modulation voltage comprises square-wave frequency modulation voltage.

8. according to the method for the described measuring voltage of claim 7, it is characterized in that the frequency of described square-wave frequency modulation voltage is at least 10 times of tested electric voltage frequency.

Images