CN105388444A - Harmonic wave measuring and correcting method for capacitor voltage transformer through transformation ratio fitting - Google Patents

Abstract

The invention brings forward a harmonic wave measuring and correcting method for capacitor voltage transformers through transformation ratio fitting. The method includes the steps: establishing a consistent equivalent circuit for capacitor voltage transformers with the same voltage level, conducting fitting according to equivalent circuit component parameters of a preset model, obtaining a transformation ratio amplitude-frequency response curve and a phase frequency response characteristic curve, adjusting the curves through a translation method or the like on the basis of a fitting result for different equivalent circuit component parameters of other models, and finally realizing correction. The wideband characteristics of capacitor voltage transformers are taken as standards for the actual transformation ratio of the capacitor voltage transformers, a measurement result of the capacitor voltage transformers is corrected at the harmonic frequency, and the problem that capacitor voltage transformers cannot be applied to harmonic wave measurement is solved. The harmonic wave measuring and correcting method is simple in calculation, exhibits the real-time performance, and enables the application bandwidth of capacitor voltage transformers to be increased.

Description

Adopt the capacitance type potential transformer harmonic measure bearing calibration of no-load voltage ratio matching

Technical field

The present invention relates to capacitance type potential transformer voltage measurement field, particularly relate to a kind of capacitance type potential transformer harmonic measure bearing calibration adopting no-load voltage ratio matching.

Background technology

Capacitance type potential transformer (CVT) is widely used in the voltage measurement of neutral-point solid ground high-pressure system, is that current voltage levels system harmonics measures topmost secondary singal source.But clear stipulaties " capacitance type potential transformer can not be used for harmonic measure " in standard GB/T/T " quality of power supply utility network harmonic wave ".

Current correlative study focuses mostly in the principle analysis aspect to capacitance type potential transformer (CVT) harmonic measure error.By setting up harmonic wave equivalent electrical circuit, provide the computing method of its corresponding parameter, to the theoretical research of capacitance type potential transformer (CVT) harmonic measure precision; By changing secondary side load and adopting the damper without model to study the measuring accuracy Changing Pattern of capacitance type potential transformer (CVT); From the angle analysis stray capacitance of transport function and coupling capacitance on the impact of capacitance type potential transformer (CVT) measuring error.But existing research is mainly for the qualitative analysis in capacitance type potential transformer (CVT), do not relate to the quantitative analysis method in each error peak point source, do not provide the bearing calibration for capacitance type potential transformer (CVT) these error characteristics yet.

Still not deeply, still Shortcomings in the quantitative analysis affecting CVT harmonic measure error with regard to Different factor, especially lacks the analysis to having different damping device CVT harmonic measure error to the study mechanism that current research produces CVT measuring error under harmonic condition.Also lack and CVT harmonic measure error is corrected.The object of the invention is to the broadband properties utilizing capacitance type potential transformer, obtain amplitude frequency curve and the phase frequency curve of no-load voltage ratio frequency response, realize the Measurement accuracy under capacitance type potential transformer harmonic frequency based on the no-load voltage ratio actual value that curve is corresponding.

Summary of the invention

The present invention proposes the broadband properties of the capacitance type potential transformer (CVT) adopting fast saturation type damper, obtain the no-load voltage ratio distortion value of capacitance type potential transformer under harmonic frequency.Matching is carried out to the amplitude versus frequency characte of this no-load voltage ratio and phase-frequency characteristic curve, realizes the correction of capacitance type potential transformer harmonic measure with the matched curve obtained.

Technical scheme of the present invention provides a kind of capacitance type potential transformer harmonic measure bearing calibration adopting no-load voltage ratio matching, CVT for same electric pressure sets up consistent equivalent electrical circuit, first matching is carried out according to the equivalent-circuit component parameter of preset model, then correct based on fitting result the different equivalent circuit element parameter of other models, described CVT is capacitance type potential transformer;

The described equivalent-circuit component parameter according to preset model carries out matching, comprise and carry out matching according to no-load voltage ratio amplitude-frequency response F (x) of the equivalent-circuit component parameter gained of preset model respectively with phase versus frequency response charac t curve H (x), obtain F _i(x) and H _{i_}(x), wherein, F _ix () is i-th section of no-load voltage ratio amplitude error in F (x), use 20lgK calibration, and unit is decibel (dB), K is the amplitude of no-load voltage ratio; H _{i_}x () is i-th section of no-load voltage ratio phase angle error, unit is degree; X is the logarithm value of frequency, i=1,2,3,4;

Describedly to correct based on fitting result, comprise the following steps,

(1) according to the equivalent-circuit component parameter of target to be corrected, the resonance frequency f of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonance is calculated ₁with compensation reactor internal resonance frequency f ₂; Preset model has two higher than the resonance frequency of power frequency, is designated as f respectively ₁₀and f ₂₀;

(2) the amplitude K of phase strain ratio K _amplitudethe mode of intrinsic standoff ratio is adopted to be expressed as follows,

$K_{Amplitude}=\frac{1}{(1+{\mathrm{j\ωC}}_{T1}+\frac{1}{{\mathrm{j\ωL}}_{Tf}+\frac{1}{{\mathrm{j\ωC}}_f}})\×\[\frac{1}{j\mathrm{\ω}(C_1+C_2)}+\frac{(\frac{R_{Lce}\×{\mathrm{j\ωL}}_{Lce}}{R_{Lce}+{\mathrm{j\ωL}}_{Lce}}+{\mathrm{j\ωL}}_{Lc})\×\frac{1}{{\mathrm{j\ωC}}_{Lc}}}{\frac{R_{Lce}\×{\mathrm{j\ωL}}_{Lce}}{R_{Lce}+{\mathrm{j\ωL}}_{Lce}}+{\mathrm{j\ωL}}_{Lc}+\frac{1}{{\mathrm{j\ωC}}_{Lc}}}\]}+1$

In formula, ω=2 π f, ω are angular frequency, and f is frequency, C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; L _lc, L _lceand R _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and resistance and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground;

To amplitude K _amplitudeadopt the linear calibration of 20lgK, according to the equivalent-circuit component parameter of target to be corrected, by f ₁and f ₂substitute in above formula, and adopt linear calibration obtain corresponding no-load voltage ratio amplitude and be designated as K ₁and K ₂;

(3) f is respectively according to preset model higher than the resonance frequency of power frequency ₁₀and f ₂₀, difference on the frequency c can be obtained ₁=f ₁-f ₁₀, c ₂=f ₂-f ₂₀;

(4) amplitude-frequency response adjustment is carried out as follows,

If i) K ₁>=F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₁if, difference on the frequency c ₁₁=lgf ₁-x ₁₁>=0, then by F ₂x () curve is to right translation c ₁₁individual unit; If c ₁₁<0, then by F ₂x () curve is to left c ₁₁individual unit;

Ii) if K ₁< F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₂if, difference on the frequency c ₁₂=lgf ₁-x ₁₂>=0, then by F ₂x () curve is to right translation c ₁₂individual unit; If c ₁₂<0, then by F ₂x () curve is to left c ₁₂individual unit;

Iii) if K ₂>=F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₁; If difference on the frequency c ₂₁=lgf ₂-x ₂₁>=0, then by F ₄x () curve is to right translation c ₂₁individual unit; If c ₂₁<0, then by F ₄x () curve is to left c ₂₁individual unit;

Iv) if K ₂< F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₂; If difference on the frequency c ₂₂=lgf ₂-x ₂₂>=0, then by F ₄x () curve is to right translation c ₂₂individual unit; If c ₂₂<0, then by F ₄x () curve is to left c ₂₂individual unit;

V) for frequency f ₁< f < f ₂frequency band adopt fitting a straight line, by resonant frequency peak point (lgf ₁, K ₁) and (lgf ₂, K ₂) determine fitting function F ₃(x); Make F ₁(x)=0;

(5) matching carrying out phase-frequency response curve also adopts the method for translation, if P _ifor

If i) f ₁<f ₁₀, then by H ₂x () is to left | c ₁|=| f ₁-f ₁₀| individual unit; If f ₁>f ₁₀, then by H ₂x () is to right translation | c ₁|=| f ₁-f ₁₀| individual unit;

Ii) if f ₂<f ₂₀, then by H ₄x () is to left | c ₂|=| f ₂-f ₂₀| individual unit; If f ₂>f ₂₀, then by H ₄x () is to right translation | c ₂|=| f ₂-f ₂₀| individual unit;

Iii) frequency is in f ₁with f ₂between response curve H ₃x () adopts quadratic function matching, hump ordinate gets real data, two-end-point is got respectively (f ₁, H ₂(f ₁)), (f ₂, H ₄(f ₂)); Make H ₁(x)=0;

(6) according to the measuring error ratio of no-load voltage ratio in no-load voltage ratio amplitude-frequency response F (x), the nominal transformation ratio K of CVT harmonic measure is obtained _nwith the amplitude K of no-load voltage ratio K _amplituderatio, the voltage magnitude measured value of CVT under harmonic frequency is multiplied by this ratio obtain voltage magnitude measured value accurately; The voltage phase angle measured value of CVT under harmonic frequency is deducted H (x), obtains voltage phase angle measured value accurately; Complete the correction to CVT measured value under harmonic frequency.

And, calculate resonance frequency f ₁and f ₂implementation is as follows,

$X_{C1}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;(C_1+C_2)}-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{T1}}$

$X_{L1}=j\&CenterDot;\frac{\mathrm{\&omega;}\&times;(L_{Lc}+L_{Lce})}{1-{\mathrm{\&omega;}}^2\&times;C_{Lc}\&times;(L_{Lc}+L_{Lce})}$

$f_1=1/\left(2\mathrm{\&pi;}\sqrt{X_{L1}{X}_{C1}}\right)$

$X_{C2}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{Lc}}$

X _L2＝j×ω×(L _Lc+L _Lce)

$f_2=1/\left(2\mathrm{\&pi;}\sqrt{X_{L2}{X}_{C2}}\right)$

Wherein, X _c1and X _l1be respectively equivalent capacitive reactance and the induction reactance of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonant circuit; X _c2and X _l2be respectively capacitive reactance and the induction reactance of compensation reactor internal resonance circuit; ω=2 π f, ω are angular frequency, and f is frequency; C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; C _t1for intermediate transformer primary side stray capacitance over the ground; L _lc, L _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground.

The present invention is using the standard of capacitance type potential transformer broadband properties as the actual no-load voltage ratio of measurement capacitance type potential transformer, the measurement result of capacitance type potential transformer under harmonic frequency is corrected, solve capacitance type potential transformer and can not be applied to this problem of harmonic measure, there is based on the harmonic measuring method of algorithm relative to Instantaneous Power Theory and wavelet transformation theory etc. the advantage of the simple and real-time of computing method, avoid in certain hour section and just carry out the problem that data analysis obtains harmonic products after a large amount of collection capacitance type potential transformer measurement result, expand the application bandwidth of capacitance type potential transformer.

Accompanying drawing explanation

Fig. 1 is the capacitance type potential transformer circuit diagram of the employing speed saturation type damper of the embodiment of the present invention;

Fig. 2 is the amplitude frequency curve fitted figure based on fitting of a polynomial of the embodiment of the present invention;

Fig. 3 is the phase frequency curve fitted figure based on fitting of a polynomial and mark matching of the embodiment of the present invention;

Fig. 4 is the no-load voltage ratio amplitude-frequency fitting correction method flow diagram of the embodiment of the present invention.

Fig. 5 is the method application schematic diagram of the embodiment of the present invention.

Embodiment

Below in conjunction with drawings and Examples, technical solution of the present invention is specifically described.

The magnitude of voltage such as grade that the present invention is adopting the capacitance type potential transformer primary side of fast saturation type damper to apply different frequency, the ratio that secondary side measurement result and primary side apply voltage is the actual no-load voltage ratio of capacitance type potential transformer.Fitting of a polynomial and mark matching is utilized to obtain the fitting function of no-load voltage ratio frequency response characteristic.According to capacitance type potential transformer equivalent circuit parameter, obtain each tuning-points frequency, the actual no-load voltage ratio value under utilizing voltage division formulas to obtain resonance frequency.According to resonance frequency and actual no-load voltage ratio value, realize translation and the conversion of fitting function, obtain capacitance type potential transformer fitting function formula accurately.Based on the measurement result of this formula correction capacitance type potential transformer, the voltage measurement making capacitance type potential transformer not only can be applied to power frequency system also can be applicable to the voltage measurement under harmonic frequency.

Capacitance type potential transformer by capacitive divider (by high-voltage capacitance C ₁with middle voltage capacitance C ₂form), electromagnetic unit is (by compensation reactor L _c, intermediate transformer T and damper Z _fform), load is (by measurement winding load Z ₁with protective winding load Z ₂form).In the embodiment of the present invention, first according to adopting the capacitance type potential transformer of Quick saturation damper to set up harmonic wave equivalent electrical circuit.C in Fig. 1 ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; L _lcand R _lc, L _lceand R _lceand C _lcbe respectively the reactance of compensation reactor coil and resistance, the reactance of iron core and resistance and stray capacitance; L _t1and R _t1, L _t2and R _t2and L _tfand R _tfbe respectively leakage reactance and the resistance of intermediate transformer primary side, measurement and protection winding and access damper winding, wherein measure and carried out equivalent merging with protection winding because capacity and output voltage are generally identical; C _t1for intermediate transformer primary side stray capacitance over the ground; L _tmand R _tmbe respectively intermediate transformer excitation reactance and resistance; L _fand R _ffor reactance and the resistance of fast saturation type damper; C _ffor damper stray capacitance over the ground; L _zand R _zfor measuring and the reactance of protective winding equivalent load and resistance; Carrying ground forms loop.Because the intermediate transformer Secondary Winding number of turn is few, in model, have ignored the stray capacitance over the ground of each winding of secondary side; A is supply voltage; N is ground.

Then, consider that the product of each manufacturer production may exist parameter value difference under same electric pressure.The present invention proposes for same electric pressure, first carries out matching according to the equivalent-circuit component parameter of preset model, then to the different equivalent circuit element parameter of other models, is processed by modes such as translation curves.Embodiment is for 400kVCVT process, and the implementation of other electric pressures is identical.Accompanying drawing 2,3 for the embodiment of the present invention for the employing speed saturation type damper capacitance type potential transformer of 400kVCVT based on the no-load voltage ratio amplitude-frequency response of the equivalent-circuit component parameter gained of preset model shown in table 1 and phase versus frequency response charac t curve, and adopt fitting of a polynomial for bent F (x) line of amplitude-frequency response characteristic, adopt fitting of a polynomial and mark matching for phase versus frequency response charac t curve H (x).Fitting result provides as follows, and wherein x is the logarithm value of frequency; F _ix () is i-th section of no-load voltage ratio amplitude error in F (x), use 20lgK calibration, and unit is decibel (dB), K is the amplitude of no-load voltage ratio; H _ix () is i-th section of no-load voltage ratio phase angle error, unit is degree, i=1,2,3,4.

Table 1 preset model equivalent-circuit component parameter

Derided capacitors equivalent capacity C	57.18nF
		Compensation reactor winding resistance R Lc	766Ω
Compensation reactor iron core resistance R Lce	9.288MΩ
		Compensation reactor winding inductance L Lc	24.71H
Compensation reactor iron inductance L Lce	148.9H
		Compensation reactor iron core electric capacity C Lc	61.17pF
Intermediate transformer first side winding resistance R T1	1403Ω
		Intermediate transformer first side winding inductance L T1	1.27H
Measure and protect and use winding resistance R T2	1054Ω
		Measure and protect and use winding inductance L T2	6.95H
Intermediate transformer excitation resistance R Tm	1070Ω
		Intermediate transformer excitation reactance L Tm	53kH
Middle change primary side stray capacitance C over the ground T1	267pF
		Damper winding leakage reactance resistance R Tf	5904Ω
Damper winding leakage reactance inductance L Tf	6.18H
		Damping circuit is stray capacitance C over the ground f	30pF
The coil-block of transformer R of damping circuit f	2725Ω
		Damping circuit Transformer Winding self-induction L f	3002H

Correlation parameter can be see:

H.J.Vermeulen,L.R.Dann,J.vanRooijen.Equivalentcircuitmodelingofacapacitivevoltagetransformerforpowersystemharmonicfrequencies[J].IEEETrans.OnPowerDelivery,1995,10(4):1743-1749.

During concrete enforcement, other value schemes also can be adopted as the equivalent-circuit component parameter of preset model, realize principle identical

Amplitude-frequency response characteristic curve-fitting results:

$\left\{\begin{array}{cc}{F}_1\left(x\right)=3.6029x^2-14.2085x+13.7354& 1.69<x\&le;2.24\\ F_2\left(x\right)=738.4x^4-7237.9x^3+26699.9x^2-43431.8x+26579.1& 2.24<x\&le;2.82\\ F_3\left(x\right)=-119.3534x+350.7125& 2.82<x\&le;3.19\\ F_4\left(x\right)=-113.4x^4+1738.6x^3-9978.4x^2+25403.8x-24228.8& 3.19<x\&le;4\end{array}\right.$

Phase versus frequency response charac t curve-fitting results:

$\left\{\begin{array}{cc}{H}_1\left(x\right)=0& 1.505<x\&le;2.401\\ H_2\left(x\right)=\frac{-0.004992}{x^2-5.756x+8.283}& 2.401<x\&le;2.820\\ \begin{array}{c}{H}_3\left(x\right)=39000x^6-695000x^5+5219000x^4-209115000x^3\\ +47139000x^2-56657000x+28370000\end{array}& 2.820<x\&le;3.187\\ H_4\left(x\right)=\frac{-0.01428}{x^2-6.016x+9.025}& 3.187<x\&le;4\end{array}\right.$

Can be seen by Fig. 2, F ₁x () is approximately equal to zero, so this fitting function directly with 0 equivalence, can make F ₁x ()=0, also can be applicable to the 400kVCVT of other models; F ₃x () is a linear function, obtained by the amplitude point line of 400kVCVT preset model two resonance frequencies, the 400kVCVT for other models can adopt same way to determine straight line by 2, obtains F ₃the fitting function of (x).

Correct based on fitting result, the concrete implementation step of embodiment is as follows:

(1) because harmonic wave equivalent electrical circuit is identical, when adopting the CVT of fast saturation type damper to be target to be corrected for other models of 400kVCVT, according to its equivalent-circuit component parameter, calculate the resonance frequency f of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonance ₁with compensation reactor internal resonance frequency f ₂.Computing method are as follows:

$X_{C1}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;(C_1+C_2)}-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{T1}}$

$X_{L1}=j\&CenterDot;\frac{\mathrm{\&omega;}\&times;(L_{Lc}+L_{Lce})}{1-{\mathrm{\&omega;}}^2\&times;C_{Lc}\&times;(L_{Lc}+L_{Lce})}$

$f_1=1/\left(2\mathrm{\&pi;}\sqrt{X_{L1}{X}_{C1}}\right)$

$X_{C2}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{LC}}$

X _L2＝j×ω×(L _Lc+L _Lce)

$f_2=1/\left(2\mathrm{\&pi;}\sqrt{X_{L2}{X}_{C2}}\right)$

Wherein, X _c1and X _l1be respectively equivalent capacitive reactance and the induction reactance of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonant circuit; X _c2and X _l2be respectively capacitive reactance and the induction reactance of compensation reactor internal resonance circuit.

ω=2 π f, ω are angular frequency, and f is frequency; C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; C _t1for intermediate transformer primary side stray capacitance over the ground; L _lc, L _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground.The equivalent-circuit component parameter of target to be corrected is adopted during calculating.

And the present embodiment preset model used has two higher than the resonance frequency of power frequency, is designated as f respectively ₁₀and f ₂₀.

(2) the amplitude K of no-load voltage ratio K _amplitudethe mode of intrinsic standoff ratio can be adopted to be expressed as:

$K_{Amplitude}=\frac{1}{(1+{\mathrm{j\&omega;C}}_{T1}+\frac{1}{{\mathrm{j\&omega;L}}_{Tf}+\frac{1}{{\mathrm{j\&omega;C}}_f}})\&times;\&lsqb;\frac{1}{j\mathrm{\&omega;}(C_1+C_2)}+\frac{(\frac{R_{Lce}\&times;{\mathrm{j\&omega;L}}_{Lce}}{R_{Lce}+{\mathrm{j\&omega;L}}_{Lce}}+{\mathrm{j\&omega;L}}_{Lc})\&times;\frac{1}{{\mathrm{j\&omega;C}}_{Lc}}}{\frac{R_{Lce}\&times;{\mathrm{j\&omega;L}}_{Lce}}{R_{Lce}+{\mathrm{j\&omega;L}}_{Lce}}+{\mathrm{j\&omega;L}}_{Lc}+\frac{1}{{\mathrm{j\&omega;C}}_{Lc}}}\&rsqb;}+1---\left(1\right)$

In formula, ω=2 π f, ω are angular frequency, and f is frequency.C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; L _lc, L _lceand R _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and resistance and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground.The equivalent-circuit component parameter of target to be corrected is adopted during calculating.

The linear calibration of 20lgK is adopted to it, is converted into the form of oscillogram ordinate in Fig. 2.By f ₁and f ₂in substitution formula (1), and linear calibration is adopted to obtain corresponding no-load voltage ratio amplitude and be designated as K ₁and K ₂.

(3) because preset model is respectively f higher than the resonance frequency of power frequency ₁₀and f ₂₀, difference on the frequency c can be obtained _i.C _i=f _i-f _i0(i=1,2), i.e. c ₁=f ₁-f ₁₀, c ₂=f ₂-f ₂₀.

(4) amplitude-frequency response adjustment:

If i) K ₁>=F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₁.If difference on the frequency c ₁₁=lgf ₁-x ₁₁>=0, then by F ₂x () curve is to right translation c ₁₁individual unit; If c ₁₁<0, then by F ₂x () curve is to left c ₁₁individual unit.

Ii) if K ₁< F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₂.If difference on the frequency c ₁₂=lgf ₁-x ₁₂>=0, then by F ₂x () curve is to right translation c ₁₂individual unit; If c ₁₂<0, then by F ₂x () curve is to left c ₁₂individual unit.

Iii) if K ₂>=F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₁.If difference on the frequency c ₂₁=lgf ₂-x ₂₁>=0, then by F ₄x () curve is to right translation c ₂₁individual unit; If c ₂₁<0, then by F ₄x () curve is to left c ₂₁individual unit.

Iv) if K ₂< F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₂.If difference on the frequency c ₂₂=lgf ₂-x ₂₂>=0, then by F ₄x () curve is to right translation c ₂₂individual unit; If c ₂₂<0, then by F ₄x () curve is to left c ₂₂individual unit.

V) for frequency f ₁< f < f ₂frequency band adopt fitting a straight line, by resonant frequency peak point (lgf ₁, K ₁) and (lgf ₂, K ₂) determine its fitting function, i.e. F ₃x () is (lgf ₁, K ₁) and (lgf ₂, K ₂) line.Make F ₁(x)=0.

(5) adjustment of phase-frequency response curve also mainly adopts the method for translation, realizes as follows,

If i) f ₁<f ₁₀, then by H ₂x () is to left | c ₁|=| f ₁-f ₁₀| individual unit; If f ₁>f ₁₀, then by H ₂x () is to right translation | c ₁|=| f ₁-f ₁₀| individual unit.

Ii) if f ₂<f ₂₀, then by H ₄x () is to left | c ₂|=| f ₂-f ₂₀| individual unit; If f ₂>f ₂₀, then by H ₄x () is to right translation | c ₂|=| f ₂-f ₂₀| individual unit.

Iii) frequency is in f ₁with f ₂between response curve H ₃x () adopts quadratic function matching, hump ordinate gets real data 0.289, two-end-point is got respectively (f ₁, H ₂(f ₁)), (f ₂, H ₄(f ₂)).F in Two coordinate point ₁and f ₂all take the logarithm.Make H ₁(x)=0.

(6) according to Fig. 2 the measuring error of the no-load voltage ratio that curve provides than 10 ^{f (x)}/ 20, the nominal transformation ratio K of CVT harmonic measure can be obtained _nwith actual no-load voltage ratio (the i.e. amplitude K of no-load voltage ratio K _amplitude) ratio.

$\frac{K_N}{K_{Amplitude}}=\frac{1}{1+{10}^{F\left(x\right)}/20}$

In formula, K _nfor the nominal transformation ratio of CVT.

The voltage magnitude measured value of CVT under harmonic frequency is multiplied by this ratio voltage magnitude measured value accurately can be obtained; The voltage phase angle measured value of CVT under harmonic frequency is deducted H (x), voltage phase angle measured value accurately can be obtained.Realize the correction to CVT measured value under harmonic frequency thus.

During concrete enforcement, the no-load voltage ratio amplitude-frequency fitting correction flow process of the embodiment of the present invention can see Fig. 4, and no-load voltage ratio phase frequency fitting correction flow process is similar.As Fig. 4, amplitude-frequency response adjustment can be divided into three phases to carry out:

First, K is judged whether ₁>=F ₂(lgf ₁₀),

If K ₁>=F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₁.And judge whether c ₁₁=lgf ₁-x ₁₁>=0, if difference on the frequency c ₁₁=lgf ₁-x ₁₁>=0, then by F ₂x () curve is to right translation c ₁₁individual unit; If c ₁₁<0, then by F ₂x () curve is to left c ₁₁individual unit.

If K ₁< F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₂.And judge whether c ₁₂=lgf ₁-x ₁₂>=0, if difference on the frequency c ₁₂=lgf ₁-x ₁₂>=0, then by F ₂x () curve is to right translation c ₁₂individual unit; If c ₁₂<0, then by F ₂x () curve is to left c ₁₂individual unit.

Then, K is judged whether ₂>=F ₄(lgf ₂₀),

If K ₂>=F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₁.And judge whether c ₂₁=lgf ₂-x ₂₁>=0, if difference on the frequency c ₂₁=lgf ₂-x ₂₁>=0, then by F ₄x () curve is to right translation c ₂₁individual unit; If c ₂₁<0, then by F ₄x () curve is to left c ₂₁individual unit.

Iv) if K ₂< F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₂.And judge whether c ₂₂=lgf ₂-x ₂₂>=0, if difference on the frequency c ₂₂=lgf ₂-x ₂₂>=0, then by F ₄x () curve is to right translation c ₂₂individual unit; If c ₂₂<0, then by F ₄x () curve is to left c ₂₂individual unit.

Finally, F is made ₁(x)=0, F ₃x () is (lgf ₁, K ₁) and (lgf ₂, K ₂) line.

See Fig. 5, current capacitance type potential transformer generally comprises capacitive divider (by high-voltage capacitance C ₁with middle voltage capacitance C ₂form), electromagnetic unit is (by compensation reactor L _c, intermediate transformer T and damper Z _fform), load is (by measurement winding load Z ₁with protective winding load Z ₂form), when specifically implementing, ratio correction of transformation device, signal generator can also be set for realizing method provided by the present invention.In addition, G is portable protective gaps, L _dfor carrier frequency thread cast-off circle, V is measurement voltage table.Compensation reactor L _cone end is connected to high-voltage capacitance C ₁with middle voltage capacitance C ₂between, the other end connects a winding of intermediate transformer T, damper Z _f, measure winding load Z ₁with protective winding load Z ₂connect the Secondary Winding of intermediate transformer T respectively.The input end of measurement voltage table is connected to measures winding load Z ₁two ends, output terminal connects the first input end of ratio correction of transformation device, and measurement voltage table is from measurement winding load Z ₁the capacitance type potential transformer Output rusults access ratio correction of transformation device that two ends gather, for gathering and the Output rusults of output capacitance formula voltage transformer (VT).Capacitance type potential transformer high-pressure side is labeled as A, and ground is labeled as N, and dividing point is designated as M.The output terminal of signal generator connects the second input end of ratio correction of transformation device, and the harmonic frequency to be measured that signal generator exports is linked into ratio correction of transformation device.Harmonic frequency to be measured is flowed to ratio correction of transformation device by signal generator, when specifically implementing, can generate corresponding harmonic frequency to be measured according to the overtone order signal received.Ratio correction of transformation device receive that signal generator sends after measured frequency, the Output rusults of no-load voltage ratio matched curve to capacitance type potential transformer according to setting up based on capacitance type potential transformer broadband properties corrects, and output calibration result.Ratio correction of transformation device can adopt DSP, realizes based on method provided by the present invention.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendment or supplement or adopt similar mode to substitute to described specific embodiment, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.

Claims (2)

1. one kind adopts the capacitance type potential transformer harmonic measure bearing calibration of no-load voltage ratio matching, it is characterized in that: the CVT for same electric pressure sets up consistent equivalent electrical circuit, first matching is carried out according to the equivalent-circuit component parameter of preset model, then correct based on fitting result the different equivalent circuit element parameter of other models, described CVT is capacitance type potential transformer;

The described equivalent-circuit component parameter according to preset model carries out matching, comprise and carry out matching according to no-load voltage ratio amplitude-frequency response F (x) of the equivalent-circuit component parameter gained of preset model respectively with phase versus frequency response charac t curve H (x), obtain F _i(x) and H _{i_}(x), wherein, F _ix () is i-th section of no-load voltage ratio amplitude error in F (x), use 20lgK calibration, and unit is decibel (dB), K is the amplitude of no-load voltage ratio; H _{i_}x () is i-th section of no-load voltage ratio phase angle error, unit is degree; X is the logarithm value of frequency, i=1,2,3,4;

Describedly to correct based on fitting result, comprise the following steps,

(1) according to the equivalent-circuit component parameter of target to be corrected, the resonance frequency f of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonance is calculated ₁with compensation reactor internal resonance frequency f ₂; Preset model has two higher than the resonance frequency of power frequency, is designated as f respectively ₁₀and f ₂₀;

(2) the amplitude K of phase strain ratio K _amplitudethe mode of intrinsic standoff ratio is adopted to be expressed as follows,

$K_{Amplitude}=\frac{1}{(1+{\mathrm{j\&omega;C}}_{T1}+\frac{1}{{\mathrm{j\&omega;L}}_{Tf}+\frac{1}{{\mathrm{j\&omega;C}}_f}})\&times;\&lsqb;\frac{1}{j\mathrm{\&omega;}(C_1+C_2)}+\frac{(\frac{R_{Lce}\&times;{\mathrm{j\&omega;L}}_{Lce}}{R_{Lce}+{\mathrm{j\&omega;L}}_{Lce}}+{\mathrm{j\&omega;L}}_{Lc})\&times;\frac{1}{{\mathrm{j\&omega;C}}_{Lc}}}{\frac{R_{Lce}\&times;{\mathrm{j\&omega;L}}_{Lce}}{R_{Lce}+{\mathrm{j\&omega;L}}_{Lce}}+{\mathrm{j\&omega;L}}_{Lc}+\frac{1}{{\mathrm{j\&omega;C}}_{Lc}}}\&rsqb;}+1$

In formula, ω=2 π f, ω are angular frequency, and f is frequency, C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; L _lc, L _lceand R _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and resistance and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground;

To amplitude K _amplitudeadopt the linear calibration of 20lgK, according to the equivalent-circuit component parameter of target to be corrected, by f ₁and f ₂substitute in above formula, and adopt linear calibration obtain corresponding no-load voltage ratio amplitude and be designated as K ₁and K ₂;

(3) f is respectively according to preset model higher than the resonance frequency of power frequency ₁₀and f ₂₀, difference on the frequency c can be obtained ₁=f ₁-f ₁₀, c ₂=f ₂-f ₂₀;

(4) amplitude-frequency response adjustment is carried out as follows,

If i) K ₁>=F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₁if, difference on the frequency c ₁₁=lgf ₁-x ₁₁>=0, then by F ₂x () curve is to right translation c ₁₁individual unit; If c ₁₁<0, then by F ₂x () curve is to left c ₁₁individual unit;

Ii) if K ₁< F ₂(lgf ₁₀), make F ₂(x)=K ₁, try to achieve the value x of corresponding x ₁₂if, difference on the frequency c ₁₂=lgf ₁-x ₁₂>=0, then by F ₂x () curve is to right translation c ₁₂individual unit; If c ₁₂<0, then by F ₂x () curve is to left c ₁₂individual unit;

Iii) if K ₂>=F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₁; If difference on the frequency c ₂₁=lgf ₂-x ₂₁>=0, then by F ₄x () curve is to right translation c ₂₁individual unit; If c ₂₁<0, then by F ₄x () curve is to left c ₂₁individual unit;

Iv) if K ₂< F ₄(lgf ₂₀), make F ₄(x)=K ₂, try to achieve the value x of corresponding x ₂₂; If difference on the frequency c ₂₂=lgf ₂-x ₂₂>=0, then by F ₄x () curve is to right translation c ₂₂individual unit; If c ₂₂<0, then by F ₄x () curve is to left c ₂₂individual unit;

V) for frequency f ₁< f < f ₂frequency band adopt fitting a straight line, by resonant frequency peak point (lgf ₁, K ₁) and (lgf ₂, K ₂) determine fitting function F ₃(x); Make F ₁(x)=0;

(5) matching carrying out phase-frequency response curve also adopts the method for translation, if P _ifor

If i) f ₁<f ₁₀, then by H ₂x () is to left | c ₁|=| f ₁-f ₁₀| individual unit; If f ₁>f ₁₀, then by H ₂x () is to right translation | c ₁|=| f ₁-f ₁₀| individual unit;

Ii) if f ₂<f ₂₀, then by H ₄x () is to left | c ₂|=| f ₂-f ₂₀| individual unit; If f ₂>f ₂₀, then by H ₄x () is to right translation | c ₂|=| f ₂-f ₂₀| individual unit;

Iii) frequency is in f ₁with f ₂between response curve H ₃x () adopts quadratic function matching, hump ordinate gets real data, two-end-point is got respectively (f ₁, H ₂(f ₁)), (f ₂, H ₄(f ₂)); Make H ₁(x)=0;

(6) according to the measuring error ratio of no-load voltage ratio in no-load voltage ratio amplitude-frequency response F (x), the nominal transformation ratio K of CVT harmonic measure is obtained _nwith the amplitude K of no-load voltage ratio K _amplituderatio, the voltage magnitude measured value of CVT under harmonic frequency is multiplied by this ratio obtain voltage magnitude measured value accurately; The voltage phase angle measured value of CVT under harmonic frequency is deducted H (x), obtains voltage phase angle measured value accurately; Complete the correction to CVT measured value under harmonic frequency.

2. adopt the capacitance type potential transformer harmonic measure bearing calibration of no-load voltage ratio matching according to claim 1, it is characterized in that: calculate resonance frequency f ₁and f ₂implementation is as follows,

$X_{C1}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;(C_1+C_2)}-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{T1}}$

$X_{L1}=j\&CenterDot;\frac{\mathrm{\&omega;}\&times;(L_{Lc}+L_{Lce})}{1-{\mathrm{\&omega;}}^2\&times;C_{Lc}\&times;(L_{Lc}+L_{Lce})}$

$f_1=1/\left(2\mathrm{\&pi;}\sqrt{X_{L1}{X}_{C1}}\right)$

$X_{C2}=-j\&CenterDot;\frac{1}{\mathrm{\&omega;}\&times;C_{Lc}}$

X _L2＝j×ω×(L _Lc+L _Lce)

$f_2=1/\left(2\mathrm{\&pi;}\sqrt{X_{L2}{X}_{C2}}\right)$

Wherein, X _c1and X _l1be respectively equivalent capacitive reactance and the induction reactance of compensation reactor and voltage-dividing capacitor and intermediate transformer primary side stray capacitance resonant circuit; X _c2and X _l2be respectively capacitive reactance and the induction reactance of compensation reactor internal resonance circuit; ω=2 π f, ω are angular frequency, and f is frequency; C ₁and C ₂be respectively the high and medium voltage electric capacity of capacitive divider; C _t1for intermediate transformer primary side stray capacitance over the ground; L _lc, L _lceand C _lcbe respectively the reactance of compensation reactor coil, the reactance of iron core and stray capacitance; L _tffor the leakage reactance of access damper winding, C _ffor damper stray capacitance over the ground.