CN102236085A

CN102236085A - Method for measuring error of current transformer under 200Hz frequency

Info

Publication number: CN102236085A
Application number: CN2011100959999A
Authority: CN
Inventors: 卢冬宁; 邵蕊; 潘正大; 周康
Original assignee: Baoding Tianwei Group Co Ltd
Current assignee: Baoding Tianwei Group Co Ltd
Priority date: 2010-12-22
Filing date: 2011-04-18
Publication date: 2011-11-09

Abstract

The invention relates to a method for measuring the error of a current transformer under a 200Hz frequency, and belongs to the technical field of transformer detection. The technical scheme comprises the following process steps of: (1) verifying the transformer to acquire a ratio difference and a phase difference of the current transformer under 50Hz; (2) performing a 50Hz test and a 50Hz no-load test on the current transformer to acquire related data of a current vector diagram of the current transformer; (3) performing a 200Hz test on the current transformer to acquire related data of the current vector diagram of the current transformer; and (4) substituting the related data into a mathematical relation acquired according to the current vector diagram of the current transformer to acquire the ratio difference multiple and the phase difference multiple of the current transformer under 200Hz and 50Hz, and multiplying by the ratio difference and the phase difference under 50Hz respectively to acquire a ratio difference and a phase difference of the current transformer under 200Hz. The method has the advantage that: the error of a 50Hz standard current transformer under the 200Hz frequency can be detected.

Description

A kind of error measurement method of current transformer under the 200Hz frequency

Technical field:

The present invention relates to a kind of error measurement method of current transformer under the 200Hz frequency, belong to transformer detection technique field.

Background technology:

Converter power transformer is in actual motion, and its winding current contains certain harmonic wave.In manufacturing plant,, carry out twice loss measurement in order to infer the load loss of converter power transformer under the service condition.Once be to carry out under rated frequency, another time is to carry out being not less than under a certain frequency of 150Hz, generally adopts the 200Hz test frequency.Calculate the load loss of converter power transformer then according to these measurement results.In load loss is measured,, generally need to use and measure current transformer because of test current is bigger.At present, China has only the standard current transformer of 50Hz, just can only examine and determine the error of current transformer under 50Hz, when when the 200Hz frequency is used, because of there not being the standard current transformer of 200Hz, so can not adopt the method for conventional calibrating to obtain the error of current transformer.

Summary of the invention:

The object of the invention provides a kind of error measurement method of current transformer under the 200Hz frequency, realizes the 50Hz standard current transformer, when the 200Hz frequency is used, detects current transformer error, solves the problems referred to above that exist in the background technology.

Technical scheme of the present invention is:

A kind of error measurement method of current transformer under the 200Hz frequency comprises following processing step: the ratio difference and the phase differential that 1. obtain current transformer 50 Hz by the calibrating mutual inductor; 2. current transformer is carried out 50 Hz test, 50 Hz no-load tests, draw current transformer current phasor figure related data; 3. current transformer is carried out the 200Hz test, draw current transformer current phasor figure related data; 4. the relationship that above-mentioned related data substitution draws according to current transformer current phasor figure, draw the phase differential multiple of current transformer under the ratio difference multiple of current transformer under 200 Hz and 50 Hz and 200 Hz and 50 Hz, again with ratio difference, the phase differential of 50Hz multiply each other the respectively ratio difference and the phase differential of current transformer 200Hz can be drawn the time.

The invention has the beneficial effects as follows: realize the 50Hz standard current transformer, when the 200Hz frequency is used, can detect current transformer error.

Description of drawings:

Fig. 1 is current transformer current phasor figure;

Among the figure: ,

Be respectively primary current and the exciting current of converting secondary; ψ is I ₂With E ₂Angle, ψ ₀For

With E ₂Angle.

Embodiment:

The invention will be further described by the following examples.

The principle of the invention:

1, draws the vector plot of current transformer and make suitable boost line, with reference to accompanying drawing 1.

The practice of boost line: be the center, be that radius is made extended line that circular arc hands over OA in the D point with OB with the O point, make the vertical line friendship OD of OD in the C point from B point again.

Because AB with

Parallel, BC is perpendicular to I ₂So, ∠ BAC=(ψ ₀-ψ), and as seen from Figure 1, I ₂With

The difference of size is the length of line segment AD, because δ is very little in the actual current mutual inductor, the difference CD of OC and OD line segment length is very little, can ignore, so can think:

I ₂-

=OA-OB=OA-OD=OA-OC=-AC

As shown in Figure 1: AC=

COS(ψ ₀-ψ); BC=AB * Sin(ψ ₀-ψ)=

Sin(ψ ₀-ψ)

2. calculate the ratio difference and the phase differential of current transformer

The current transformer ratio difference is:

ε（%）=

?COS（ψ ₀-ψ）×100 (1)

The phase differential of current transformer is With I ₂(OA) angle δ (radian).When angle was very little, its radian value was approximately equal to the sine value at this angle, thus δ=Sin δ= =

Sin(ψ ₀-ψ) (2)

As under 200 Hz and 50 Hz, applying same primary current (promptly ₂₀₀=

₅₀), can draw:

The ratio difference multiple of current transformer under 200 Hz and 50 Hz:

K=?

(3)

The phase differential multiple of current transformer under 200 Hz and 50 Hz:

K _δ=

(4)

If our calibrating obtains ratio difference and the phase differential of 50 Hz, measure parameters needed in formula (3) and (4) again, the ratio difference of mutual inductor and phase differential in the time of just can drawing 200 Hz.

Embodiment more specifically:

1, obtains ratio difference and the phase differential of current transformer 50 Hz by the calibrating mutual inductor;

2,50 Hz test

Once add a percentage of rated current, secondary adds nominal load, measures electric current I in its load with 0.5 grade of power analyzer ₂, voltage U ₂, active power P and reactive power Q.

Then can draw the resistance value and the reactance value of mutual inductor actual load by following formula:

R ₁=

X ₁=

Measure the direct current resistance R of secondary winding in current transformer with 0.2 grade of direct-flow double bridge ₀

The leakage reactance X of Secondary Winding ₀Calculating:

Expire in annular when the secondary wire turn is evenly rich, and first and second winding is symmetrical fully, then X ₀=0

In fact first and second winding can not be symmetrical fully, but X ₀Be worth very little in the ordinary course of things.Can choose X by following situation ₀, when rated primary current value≤600A, X ₀≈ 0.05～0.1 Ω; When rated primary current value 〉=600A, X ₀≈ 0.1～0.2 Ω

Can draw thus: Z=

Ψ then ₅₀=tg ^-1

(Ψ ₅₀Be E ₂With I ₂Angle)

3, the unloaded I of 50 Hz ₀Measurement

Need add no-load voltage in zero load is measured, no-load voltage calculates by following formula:

U=I ₂×Z

Give the Current Transformer Secondary making alive with 0.1 grade of alternating-current voltage source, measure the no-load current I of Secondary Winding with 0.5 grade of power analyzer ₀, active power P and reactive power Q.

R then ₂=

X ₂=

Ψ ₀₅₀=tg ^-1(Ψ ₀₅₀Be E ₂With I ₀Angle)

4,200Hz test

Stipulate by standard GB 1208-97 " current transformer ": examine and determine current transformer with inductive load.Therefore, we think that current transformer secondary load is a perception.Frequency is to not influence of resistance value, and is only influential to reactance value.

Because of R _L=2 л fL event R when 200Hz ^ˊ=R ₁+ R ₀

X ^ˊ=

（X ₁+X ₀）=4（X ₁+X ₀）

Z ₂₀₀=

Ψ ₂₀₀=tg ^-1

(Ψ ₂₀₀E during for 200Hz ₂With I ₂Angle)

No-load voltage U during 200Hz ₂₀₀=I ₂* Z ₂₀₀

Give the Current Transformer Secondary making alive with 0.1 grade of alternating-current voltage source, measure the no-load current I of Secondary Winding with 0.5 grade of power analyzer ₀, active power P and reactive power Q

Calculate: R ₂₀₀= X ₂₀₀=

Ψ ₀₂₀₀=tg ^-1

(Ψ ₀₂₀₀E during for 200Hz ₂And I ₀Angle)

5, measure above data after, bring formula ⑶, ⑷ into and calculate K _εAnd K _δ, again with ratio difference, the phase differential of 50Hz multiply each other the respectively ratio difference and the phase differential of current transformer can draw 200Hz the time.

Claims

1. a kind of error measurement method of current transformer under the 200Hz frequency is characterized in that comprising following processing step: the ratio difference and the phase differential that 1. obtain current transformer 50 Hz by the calibrating mutual inductor; 2. current transformer is carried out 50 Hz test, 50 Hz no-load tests, draw current transformer current phasor figure related data; 3. current transformer is carried out the 200Hz test, draw current transformer current phasor figure related data; 4. the relationship that above-mentioned related data substitution draws according to current transformer current phasor figure, draw the phase differential multiple of current transformer under the ratio difference multiple of current transformer under 200 Hz and 50 Hz and 200 Hz and 50 Hz, again with ratio difference, the phase differential of 50Hz multiply each other the respectively ratio difference and the phase differential of current transformer 200Hz can be drawn the time.