CN101930841A - Temperature rise design method of resin-encapsulated transformer winding - Google Patents

Abstract

The invention relates to a temperature rise design method of a high-voltage and a low-voltage winding of a resin-encapsulated self-cooled transformer based on an actual average temperature rise model, belonging to the technical field of transformers. The invention comprises a manufacturing method of the actual average temperature rise model and a method for designing temperature rise according to the model, which comprises the following steps: taking actually measured temperature rise parameter as a basis, manufacturing the actual average temperature rise model, using the model and the functional relation curve of the actual average temperature rise value delta Q and apparent thermal load q to design temperature rise. The invention can replace the traditional complicated calculation on heat conduction, convection and irradiation, fast design the average temperature rise value basically in line with the actual measurement value, greatly simplify the design procedures, save design time, and improve accuracy of design value and is especially applicable to resin-encapsulated high-voltage winding without airway inside and low-voltage winding with or without an airway inside, at and below 35kV and at and below 6300kVA, the temperature rise test qualification rate reaches 100%.

Description

A kind of resin-encapsulate Transformer Winding Temperature Rise method for designing

Technical field

The present invention relates to a kind of temperature rise design method, belong to the transformer technology field based on actual average temperature rise model with epoxy resin enclosed naturally air-cooled power transformer high and low pressure winding.

Background technology

In the high and low pressure winding of power transformer, exist resistance loss, eddy current loss and lead-in wire loss etc.These losses produce heat in the high and low pressure winding.The rule that the part of these heats is transmitted according to heat, form by conduction, convection current, radiation from the winding internal delivery to the surface, be dispersed into the ambient air medium from the surface and go, another part heat then is stored in the winding of transformer, and winding temperature is raise.The absolute number that its temperature raises than ambient temperature is unit temperature rise with K.

When winding temperature raise, the insulating material temperature in the winding was also along with rising.Insulating material is aging gradually along with the rising of temperature, influences the useful life of insulating material, just influences the safe operation and the useful life of transformer.For useful life of guaranteeing transformer in 20～30 years, must be when satisfying all other electrical technology performances of transformer, temperature rise is designed, make temperature rise be no more than the maximum temperaturerise of insulating material permission (as national Specification, the dry-type transformer of F class F insulation system, hottest spot temperature must not surpass 155 ℃, and its temperature rise must not surpass 100K).Temperature rise is too high, influences life of product, as guaranteeing useful life, then will take forced air cooling to product, or reduces output capacity, and to reduce temperature rise, this comes down to substandard product.Temperature rise is low excessively, increases small product size, increases cost, and both are neither desirable.Therefore, the temperature rise design is the indispensable program of design of transformer, and finally will examine the measured value of temperature rise by type approval test, looks the temperature limit whether it has surpassed the insulating material regulation.

The radiating mode of dry-type power transformer winding, be with heat from winding inside by inside and outside surface and the encapsulating resin of heat conduction to winding, low pressure winding part heat is also drawn copper bar by heat conduction to conducting electricity.Outer surface at the winding pour mass mainly is dispersed in the ambient air medium by the mode of convection current and radiation, and heat conduction can be ignored.When temperature rise is too high, must in winding, add the heat radiation air flue, increase area of dissipation, because the air flue width has size, must influence the effect of convection current and radiation, then will convert air flue during design temperature rise, will consider the influence to hottest spot temperature in heat transfer process of the radial thickness of winding simultaneously, these all must be proofreaied and correct temperature rise when design.

The temperature rise design of dry-type transformer has several different methods in history along with the continuous development and the maturation of this product.Various methods for designing all are the forms according to heat conduction, convection current, radiation, consider the influence of air flue simultaneously to radiation, convection current, calculate its referring factor, and introduced empirical coefficient to a great extent and made design result generation deviation, the computational process that has is comparatively numerous and diverse, particularly to the Transformer Winding of larger capacity, more difficult assurance.

Summary of the invention:

The objective of the invention is in the conduction of following the heat transmission, convection current, radiation three big rules, based on the actual tests data, avoid the complicated calculation process, various empirical coefficients are summed up as a total model coefficient, seek a kind of based on actual average temperature rise model not only accurately but also simple and direct temperature rise design method, can promptly draw the size of average temperature rising design result and control temperature rise more accurately.

The object of the present invention is achieved like this, and it comprises the manufacture method of actual average temperature rise model and according to the method for actual average temperature rise modelling temperature rise:

1), actual average temperature rise model production method:

1., actual loading test, determine actual average temperature rise Δ Q parameter: the resin-encapsulate Transformer Winding of the big low capacity of difference, different radial thickness, difference being sealed thickness is carried out actual temperature rise test; The fictitious load method that test method allow to adopt according to national standard, and each coil temperature rise when coil midstream crossed rated current and iron core and be rated excitation proofreaies and correct, and calculates the actual average temperature rise Δ Q of every kind of coil;

2., arrangement actual average temperature rise Δ Q parameter: by radial thickness of difference and the different windings of sealing thickness, taxonomic revision actual average temperature rise Δ Q data;

3., determine the apparent area parameter: with winding is that a heating is whole, calculates the heat radiation apparent area S (m of every product winding of above-mentioned correspondence ²);

4., computational load loss P _kParameter: the load loss P during reference temperature that every the product winding that calculates above-mentioned correspondence is selected insulation thermal endurance class _k, comprise resistance loss, eddy current loss and lead-in wire loss; These losses are existing design in the design of transformer process;

5., measuring and calculating apparent heat load q parameter: the apparent heat load q that calculates every product winding of above-mentioned correspondence:

$\begin{array}{cc}q=\frac{P_k}{S}& (w/m^2)\end{array}$

This apparent heat load q value is the thermic load value of apparent area correspondence, and it is the apparent thermic load value of the total radiating effect of reaction heat conduction, convection current, radiation three;

6., on rectangular coordinate, mark the quadrantal points of respectively classify winding apparent thermic load value q and corresponding actual average temperature rise value Δ Q;

7., with all quadrants point on the coordinate, press the difference classification of winding, draw out different radial thickness and the different actual average temperature rise curves of sealing thickness;

8., get one section curve commonly used, the actual average temperature rise curve of this section is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q according to the straight line character of this model;

2), according to the method for actual average temperature rise modelling temperature rise:

1., according to the result of epoxy resin enclosed naturally air-cooled power transformer technical performance calculation of parameter, the load loss P when obtaining winding and be the reference temperature of selected insulation thermal endurance class _k(watt), comprise resistance loss, eddy current loss and lead-in wire loss sum;

2., according to the physical dimension of transformer high and low pressure winding, calculate its apparent area S (m ²);

3., measuring and calculating apparent thermic load value q; Q=P _k/ S (W/m ²)

4., according to the linear function relational expression of average temperature rising Δ Q in the actual average temperature rise model and apparent heat load q, calculate the average temperature rising Δ Q of winding; Relatively whether this average temperature rising Δ Q value adheres to specification;

5. or again press apparent heat load q and the corresponding curve of average temperature rising Δ Q in the actual average temperature rise model, look into and be averaged temperature rise Δ Q value, and compare with above-mentioned measuring and calculating value and corresponding class of insulation temperature limit, look above two kinds of average temperature rising Δ Q values and whether adhere to specification;

6., when surpassing the regulation of designing requirement, under the prerequisite of the requirement of satisfying the transformer technology performance parameter, winding is redesigned as if above-mentioned temperature rise value, adjust the wire gauge sectional area and the profile physical dimension of winding, its load loss is reduced, increase area of dissipation, reduce the q value;

7., 1. the parameter of redesign winding is carried out to demonstration 5. again;

8., carry out actual temperature rise test, with the accuracy of checking design;

9., the nargin of temperature rise design: consider that hottest spot temperature is the position of upwards departing from the middle part of winding thickness; And above-mentioned design result is meant the average temperature rising of winding, is not temperature rise at the hottest point, and design must leave certain nargin; Experience shows that temperature rise of hot spot exceeds 2～3k than average temperature rising, and therefore, design margin should be littler by about 2～3% than allowing maximum.

The present invention has adopted following technical measures:

1., based on actual measurement temperature rise parameter, find out its temperature rise curvilinear motion rule corresponding with the apparent heat load, derive measure formula again, the temperature measurement data are promptly arranged earlier, after the temperature rise law curve is arranged, make actual average temperature rise model and launch mode type function according to temperature rise curve again, guaranteed measuring and calculating or the accuracy of searching this curve and function.

2., three big phenomenons of the conduction of heat transmission, convection current, radiation are simplified to comprehensive heat radiation phenomenon equivalence, that contained three big hot transport phenomenons, various empirical coefficients are summed up as a total model coefficient, have avoided the calculating of numerous and diverse conduction, convection current, radiation.

3., area of dissipation is reduced to apparent area, and avoid the conversion of various air flue coefficients.

Adopt the function relation curve of actual average temperature rise model of the present invention and actual average temperature rise value Δ Q and apparent heat load q, the calculating of alternative traditional, numerous and diverse heat conduction, convection current and radiation, can more promptly design the average temperature rising numerical value that conforms to substantially with measured value, simplified widely and designed program, the save design time, improve the accuracy of design value, be specially adapted to 35KV and following, 6300KVA and the following inner no air flue winding of resin-encapsulate high pressure and low pressure inside has, no air flue winding, the temperature rise test qualification rate can reach 100%.

Description of drawings

The typical structure schematic diagram of Fig. 1, epoxy casting Transformer Winding and iron core.

Fig. 2, the inner no air flue winding actual average temperature rise curve of high pressure of the present invention (outward) and model rectilinear.

Fig. 3, low pressure of the present invention (interior) inside have, no air flue winding actual average temperature rise curve and model rectilinear.

Among Fig. 1: core limb 1, the inner air flue 2 of low pressure, low pressure winding 3, high pressure winding 4, encapsulated layer 5, outer surface 6, inner surface 7, air flue 8 between the high and low pressure, outer surface 9, air flue inner surface 10, inner surface 11, encapsulated layer 12.

Embodiment:

The present invention can specifically implement according to the technology in the summary of the invention, the temperature rise of design A, E, B, F, H and C level different insulative system, now be designed to embodiment and further specify, yet scope of the present invention is not limited to following embodiment with the temperature rise of F class F insulation system commonly used.

Embodiment divides two parts to describe: actual average temperature rise model production method and according to the method for actual average temperature rise modelling temperature rise.

One, below in conjunction with reality actual average temperature rise model production method of the present invention is further described:

The actual average temperature rise model production method of embodiment 1-1, inner no gas duct high pressure winding:

1), actual loading test, determine actual average temperature rise Δ Q parameter: the resin-encapsulate Transformer Winding of the big low capacity of difference (as the 30-1250KVA series of products), different radial thickness (20-40mm), difference being sealed thickness (inner surface 2-3mm, outer surface 4-6mm) is carried out actual temperature rise test; The fictitious load method that test method allow to adopt according to national standard, and each coil temperature rise when coil midstream crossed rated current and iron core and be rated excitation proofreaies and correct, and calculates the actual average temperature rise Δ Q of every kind of coil;

2), arrangement actual average temperature rise Δ Q parameter: by radial thickness of difference and the different windings of sealing thickness, taxonomic revision actual average temperature rise Δ Q data;

3), determine the apparent area parameter: with winding is that a heating is whole, calculates the heat radiation apparent area S (m of every product winding of above-mentioned correspondence ²);

4), computational load loss P _kParameter: every product winding reference temperature calculating above-mentioned correspondence is 120 ℃ load loss P _k, comprise resistance loss, eddy current loss and lead-in wire loss; When calculating, the transformer technology performance parameter provided;

5), measuring and calculating apparent heat load q parameter: the apparent heat load q that calculates every product winding of above-mentioned correspondence:

$\begin{array}{cc}q=\frac{P_k}{S}& (w/m^2)\end{array}$

This heat load q value is the thermic load value of apparent area correspondence, and it is the apparent thermic load value of the total radiating effect of reaction heat conduction, convection current, radiation three;

6), on rectangular coordinate, mark the quadrantal points of respectively classify winding apparent thermic load value q and corresponding actual average temperature rise value Δ Q;

7), with all quadrants point on the coordinate, press the difference classification of winding, draw out different radial thickness and the different actual average temperature rise curves of sealing thickness;

8), get 45～100K section curve commonly used, calculate inner surface and seal thickness 2-3mm, outer surface is sealed thickness 4-6mm, layer insulation 0.4-0.6mm, the high pressure of radial size 20-40mm (outward) winding actual average temperature rise curve (seeing accompanying drawing 2), this exponential curve is bent upwards a little as can be seen, index n is slightly larger than 1, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q according to the straight line character of this model:

ΔQ＝0.1q+15(k) (1)

By actual average temperature rise curve and the linear function computing formula derived of equivalence as can be known:

As apparent heat load q=850w/m ²The time, Δ Q=100k, the maximum apparent heat load of expression F class F insulation must not surpass 850W/m ²If surpass, then when design, adjust the q value, promptly increase area of dissipation or reduce load loss, the control temperature rise is no more than 100K;

Embodiment 1-2, inner no air flue appearance are sealed thickness 1-2mm, the actual average temperature rise model production method of radial size 15-35mm low pressure winding:

1), implementation procedure is with embodiment 1-1 the 1st) money～7th) money;

2), the actual average temperature rise curve is seen accompanying drawing 3;

Get 50～100k section curve commonly used, as can be seen, this exponential function curve is bent downwardly a little, index n is slightly less than 1, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q according to the straight line character of this model:

ΔQ＝0.125q+12.5 (k) (2)

By actual average temperature rise curve and the linear function derived as can be known:

As apparent heat load q=700w/m ²The time, Δ Q=100k promptly represents the winding of the inner no air flue of F class F insulation, maximum apparent heat load must not surpass 700w/m ²If surpass, then adjust the q value, promptly increase area of dissipation or reduce load loss, the control temperature rise is no more than 100K.

There is the wide 12-15mm of air flue embodiment 1-3, inside, and appearance is sealed thickness 1-2mm, the actual average temperature rise model production method of air flue both sides radial size 15-30mm low pressure winding:

When the apparent heat load of inner the no air flue of low pressure winding surpasses the temperature limit that insulation allows, when adjusting q value and also missing one's aim, must set up air flue in low pressure winding inside, with the increase area of dissipation, make the thermic load value reduction.

1), implementation procedure is with embodiment 1-1 the 1st) money～7th) money;

2), the actual average temperature rise curve is seen accompanying drawing 3;

Get 50～100k section curve commonly used, as can be seen, this exponential function curve also is bent downwardly a little, index n is slightly less than 1, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q according to the straight line character of this model:

ΔQ＝0.143q+28.5 (k) (3)

By actual average temperature rise curve and the linear function derived as can be known:

As apparent heat load q=500w/m ²The time, Δ Q=100k represents that promptly there is the winding of the wide air flue of 12-15mm F class F insulation inside, maximum apparent heat load must not surpass 500w/m ²If surpass, then adjust the q value, promptly increase area of dissipation or reduce load loss, the control temperature rise is no more than 100K.

Two, below in conjunction with reality the present invention is further described according to the method for actual average temperature rise modelling temperature rise:

Embodiment 2-1: design 1 three-phase, 50 hertz, the temperature rise of 1250KVA ast resin transformer winding F class F insulation, its average temperature rising is no more than 97K.The inner no air flue of high pressure (outward) winding, low pressure (interior) winding is provided with the wide air flue of 12mm.

1, high pressure winding temperature rise design:

1), at first calculates high pressure winding load loss P _K1

Existing design load in the design of transformer process, reference temperature is 120 ℃ resistance loss P _R=5756w;

Eddy current loss P _N1Account for 10.4%, i.e. P _N1=5756 * 10.4%=599W;

The lead-in wire loss is ignored;

Then reference temperature is 120 ℃ load loss P _K1=P _R+ P _N1=5756+599=6355W.

2), according to high pressure winding physical dimension, calculate its single winding apparent area S1=2.825m ²

3), measuring and calculating apparent thermic load value q ₁:

q ₁＝P _k1/S ₁＝6355/2.825×3＝750w/m ²

4), by formula (1) calculates high pressure winding average temperature rising Δ Q ₁:

Δ Q ₁=0.1 * 750+15=90k＜F level 100K limit value

5), check in Δ Q by accompanying drawing 2 actual temperature rise curves ₁=90.5k＜F level 100K limit value, and satisfy nargin.

6), if during the 100K of temperature rise measuring and calculating value overshoot, then need redesign the high pressure winding temperature rise, adjust the wire gauge sectional area and the profile physical dimension of design winding, its load loss is reduced, increase area of dissipation, reduce the q value, but must at first satisfy the requirement of transformer technology performance parameter.

7), through actual temperature rise test, Δ Q ₁=86k＜F level 100K limit value

8), design conclusion: design load and test value are close, meet F stage temperature rise limit value regulation.

2, low pressure winding temperature rise design:

1), calculates low pressure winding load loss P earlier _K2:

Existing design load in the design of transformer process, reference temperature is 120 ℃ resistance loss Pr=3437w,

Eddy current loss P _N2Measuring and calculating: adopt 2 * 920mm foil, 15 circles are through measuring and calculating

P _n2＝26.92％×3437＝925W

Lead-in wire loss measuring and calculating value is P _i=358W

Reference temperature is 120 ℃ load loss P _K2=P _r+ P _N2+ P _i=3437+925+358=4720W

2), according to low pressure winding physical dimension, calculate its single winding apparent area, and deduct and hidden in the air flue

The area of lid is through measuring and calculating apparent area S ₂=3.476m ²

3), measuring and calculating apparent thermic load value q ₂:

q ₂＝P _k2/S ₂＝4720/3.476＝452.6w/m ²

4), by formula (3) calculate low pressure winding average temperature rising Δ Q ₂:

Δ Q ₂The limit value of=0.143 * 452.6+28.5=93.2k＜F level 100K

5), check in Δ Q by accompanying drawing 3 actual temperature rise curves ₂The limit value of=94k＜F level 100K, and satisfy nargin.

6), if during the 100K of temperature rise measuring and calculating value overshoot, then need to redesign the low pressure winding temperature rise, its load loss is reduced, adjust the long-pending and profile physical dimension of cross-sectional area of conductor of design low pressure winding, increase area of dissipation, reduce the q value, but must at first satisfy the requirement of transformer technology performance parameter.

7), through actual tests, Δ Q ₂The limit value of=90k＜F level 100K

8), design conclusion: design load and test value are close, meet F stage temperature rise limit value regulation.

Embodiment 2-2: design 1 three-phase, 50 hertz, the temperature rise of 1250KVA ast resin transformer winding F class F insulation, its winding temperature rise of hot spot limit value is no more than 100K, and average temperature rising is no more than 97K.The inner no air flue of high pressure (outward) winding, low pressure (interior) winding is provided with the wide air flue of 12mm.

One, high pressure winding temperature rise design

(1), Preliminary design:

1), at first calculates high pressure winding load loss P _K1

Existing design load in the design of transformer process, reference temperature is 120 ℃ resistance loss P _R=6689w;

Eddy current loss P _N1Account for 8.4%, i.e. P _N1=6689 * 8.4%=562w;

The lead-in wire loss is ignored;

Then reference temperature is 120 ℃ load loss P _K1=P _R+ P _N1=6689+562=7251w.

2), according to high pressure winding physical dimension, calculate its single winding apparent area S ₁=2.692m ²

3), measuring and calculating apparent thermic load value q ₁:

q ₁＝P _k1/S ₁＝7251/2.692×3＝897.8w/m ²

4), by formula (1) calculates high pressure winding average temperature rising Δ Q ₁:

Δ Q ₁=0.1 * 897.8+15=104.8k＞F level 100K limit value

5), check in Δ Q by accompanying drawing 2 actual temperature rise curves ₁＞F level 100K limit value

6), by the measuring and calculating of above-mentioned average temperature rising with look into and get curve as can be known, the 100K restriction of temperature rise overshoot, and the total load loss together with the low pressure winding exceeds national standard, temperature rise and load loss design are all undesirable, must readjust design, increase the wire gauge sectional area, reduce load loss, increase overall dimension,, reduce the q value to increase area of dissipation.

(2), adjust design:

1), presses above-mentioned adjustment mentality of designing, the process of repetition transformer technology performance parameter design, measuring and calculating high pressure winding load loss P _K1

Adjusting design of transformer process of design value, reference temperature is 120 ℃ a resistance loss

P _R＝5756w；

Eddy current loss P _N1Account for 10.4%, i.e. P _N1=5756 * 10.4%=599W;

The lead-in wire loss is ignored;

Then reference temperature is 120 ℃ load loss P _K1=P _R+ P _N1=5756+599=6355W.

2), according to high pressure winding physical dimension, calculate its single winding apparent area S ₁=2.825m ²

3), measuring and calculating apparent thermic load value q ₁:

q ₁＝P _k1/S ₁＝6355/2.825×3＝750w/m ²

4), by formula (1) calculates high pressure winding average temperature rising Δ Q ₁:

Δ Q ₁=0.1 * 750+15=90k＜F level 100K limit value

5), check in Δ Q by accompanying drawing 2 actual temperature rise curves ₁=90.5k＜F level 100K limit value, and satisfy nargin.

6), through actual temperature rise test, Δ Q ₁=86k＜F level 100K limit value

7), design conclusion: design load and test value are close, meet F stage temperature rise limit value regulation.

Two, low pressure winding temperature rise design

(1), Preliminary design:

1), at first calculates low pressure winding load loss P _K2:

Existing design load in the design of transformer process, reference temperature is 120 ℃ a resistance loss

Pr＝3632w，

Eddy current loss P _N2Measuring and calculating: adopt 2 * 920mm foil, 15 circles are through measuring and calculating

P _n2＝25.47％×3632＝925w

Lead-in wire loss measuring and calculating value is P _i=355w

Reference temperature is 120 ℃ load loss P _K2=P _r+ P _N2+ P _i=3632+925+355=4912w

2), according to low pressure winding physical dimension, calculate its single winding apparent area, and deduct covered area in the air flue, through measuring and calculating apparent area S ₂=3.289m ²

3), measuring and calculating apparent thermic load value q ₂:

q ₂＝P _k2/S ₂＝4912/3.289×3＝497.8w/m ²

4), by formula (3) calculate low pressure winding average temperature rising Δ Q ₂:

Δ Q ₂The limit value of=0.143 * 497.8+28.5=99.7k＜F level 100K

5), check in Δ Q by accompanying drawing 3 actual temperature rise curves ₂The limit value of=99.5k＜F level 100K

6), the measuring and calculating of above-mentioned average temperature rising and look into and get curve as can be known, though temperature rise value surpasses the limit value of the 100K of regulation, press design margin, should be than threshold limit value less than 3%, be 97K, the temperature rise design load still is bigger than normal, and is also undesirable, should readjust design, it is long-pending to increase cross-sectional area of conductor, reduces load loss, increases overall dimension, to increase area of dissipation, reduce the q value.

(2), adjust design:

1), by the above-mentioned thinking of readjusting design, repeat the process of transformer technology performance parameter design, measuring and calculating low pressure winding load loss P _K2:

Adjusting design of transformer process of design value, reference temperature is 120 ℃ resistance loss Pr=3437w,

Eddy current loss P _N2Measuring and calculating: adopt 2 * 920mm foil, 15 circles are through measuring and calculating

P _n2＝26.92％×3437＝925W

Lead-in wire loss measuring and calculating value is P _i=358W

Reference temperature is 120 ℃ load loss P _K2=P _r+ P _N2+ P _i=3437+925+358=4720W

2), according to low pressure winding physical dimension, calculate its single winding apparent area, and deduct covered area in the air flue, through measuring and calculating apparent area S ₂=3.476m ²

3), measuring and calculating apparent thermic load value q ₂:

q ₂＝P _k2/S ₂＝4720/3.476＝452.6w/m ²

4), by formula (3) calculate low pressure winding average temperature rising Δ Q ₂:

Δ Q ₂The limit value of=0.143 * 452.6+28.5=93.2k＜F level 100K

5), check in Δ Q by accompanying drawing 3 actual temperature rise curves ₂The limit value of=94k＜F level 100K, and satisfy nargin.

6), through actual tests, Δ Q ₂The limit value of=90k＜F level 100K

7), design conclusion: design load and test value are close, meet F stage temperature rise limit value regulation.

The creativeness of the present invention and existing method for designing compares:

First kind of method for designing: before the sixties in last century, the power transformer production technology of resin-encapsulate is still at initial period, the design of winding average temperature rising is with reference to the self cooling dry-type transformer temperature rise design method of the non-encapsulate air of the former Soviet Union, earlier iron core, coil are regarded as the heating individuality that is independent of each other, again the area of dissipation in the heat radiation air flue is carried out the coefficient conversion, calculate iron core, inside and outside coil temperature rise Δ Q separately ₀', Δ Q ₁', Δ Q ₂', consider the temperature rise correction amount delta τ that takes place owing to the different thermal radiations that take place of temperature between them then ₀', Δ τ ₁', Δ τ ₂', the former temperature rise calculated value is proofreaied and correct, draw coil average temperature rising value.(see document 1, " dry-type transformer " Shenyang Transformer Research Institute information section 1989.6; Document 2, " air self cooled transformer temperature rise calculating " Shanghai transformer factory 1969.10), the outer winding average temperature rising of its high pressure is designed program as follows:

1., calculate the area of dissipation S of winding outer surface ₁(m ²)

2., calculate the area of dissipation S of winding inner surface ₂(m ²)

3., calculate the referring factor of air flue to inboard radiating surface

In the formula: A is air flue width (mm); H is air flue height (mm)

4., calculate equivalent area of dissipation S=S ₁+ α S ₂(m ²)

5., calculate the mean heat flux of winding

In the formula: P _kShort circuit loss (w) for winding

6., calculate temperature rise Δ Q '=0.36q that winding produces ^0.8(k)

7., carry out temperature rise and proofread and correct Δ τ and calculate: utilize the above-mentioned the 6. money formula, this moment, q was the heat load difference of two radiating surfaces of heat exchange.Difference is timing, and Δ τ is for just; When difference was negative, Δ τ was a negative value.

8., the winding average temperature rising Δ Q=Δ Q ' ± Δ τ (k) after the correction

For example: a three-phase high-voltage winding is arranged, external diameter

Internal diameter

Height 198.5mm, air flue width 10mm, 6 of every phases, short circuit loss 347w then is calculated as follows:

S ₁＝3×202π×198.5×10 ^-6＝0.378(m ²)

S ₂＝3(186π-6×10)×198.5×10 ^-6＝0.312(m ²)

A＝5.5(mm)

$\mathrm{\α}=0.56{\left(\frac{{5.5}^{1.6}}{220}\right)}^{\frac{1}{4}}=0.239$

S＝0.378+0.239×0.312＝0.4685(m ²)

$q=\frac{347}{0.4685}=740(w/m^2)$

ΔQ′＝0.36×740 ^0.8＝71k

Proofread and correct temperature rise Δ τ=0

ΔQ＝71-0＝71k

From first kind of method for designing as can be seen, this condition of using that applies a formula is:

1., be applicable to the self cooling coil of the non-air of sealing;

2., computing formula Δ Q '=0.36q ^0.8In coefficient 0.36 and index 0.8 all are empirical coefficients, and be subjected to test model restriction less than normal at that time, inapplicable to the larger capacity transformer.

Thereby, the winding of this incompatibility resin-encapsulate that applies a formula.Facts have proved that calculate with this formula, its design load is than measured value 15～20K on the low side.Larger capacity product particularly, with the final result of the test of this formula design often temperature rise transfinite, it is qualified that the type approval test of product temperature rise is difficult to.

Second kind of method for designing: the sixties in last century, the German has invented and a kind ofly has been stained with epoxy resin with glass fiber and does the dry-type transformer that twines of insulation, be similar to present resin-encapsulate transformer, its temperature rise design is by convection current and two kinds of forms of radiation based on heat radiation: based on heat loss through convection, exchange with radiation between generation heat balance between interior winding and iron core; Outside on the winding, inboard based on heat loss through convection, the outside is based on heat loss through radiation, and with interior winding generation heat balance exchange carry out temperature rise proofread and correct (see German wound form do become calculate single).Design high pressure (outer winding) program is as follows:

1., calculate the inside and outside surface thermal load q of outer winding (w/m ²)

2., calculate the inboard air flue conversion factor of outer winding

3., calculate the inboard effectively convection coefficient of outer winding

In the formula

For F level α _k=0.76

4., calculate effectively convection coefficient of the outer winding outside

5., calculate the outer winding total equivalent coefficient of heat transfer K in medial and lateral ₁=D ₁₂α ₁+ D ₁₁α ₀+ F ₁F ₀

In the formula: α ₀Be outside convection current allocation proportion 0.58～0.53;

α ₁Be inboard convection current allocation proportion 0.42～0.47

f ₀Be outside radiation distribution ratio 0.37～0.34;

F ₁Be outside radiation coefficient 7～10 (w/m ².k), the F class F insulation is 8.6.

6., proofread and correct preceding temperature rise Δ Q ₀=q/k ₁(k)

7., carry out heat balance and proofread and correct temperature rise: proofread and correct by whenever differing the principle that 3.5k will make the other side improve the 1k temperature rise between inside and outside winding.Do not proofread and correct when not carrying out temperature rise in the high pressure during no air flue.

For example: a 1250KVA high-tension coil, the wide 31mm of air flue between high and low pressure, the wide 24mm of the inner air flue of high pressure, reactance height 544mm.

1., the high pressure winding is inboard calculates:

Surface thermal load q ₁₂=688.99 (w/m ²)

Air flue mean breadth A=(31+24)/2=27.5 (mm)

The air flue conversion factor

Effective convection coefficient

Preceding temperature rise Δ Q is not proofreaied and correct in the inboard ₁₂'=688.99/7.636=90.22 (k)

2., calculate in the high pressure winding outside:

Surface thermal load q ₁₁=995.67 (w/m ²)

The air flue conversion factor

Effective convection coefficient

${\mathrm{<figure-callout\; id="11"\; label="D"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">D</figure-callout>}}_{11}=\frac{9\&times;0.76}{{(540/1000)}^{0.25}}=7.97(w/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">m</figure-callout>}}^2\&CenterDot;k)$

α ₀Be 0.58; α ₁Be 0.42; F ₀Get 0.37; F ₁Get 8.6;

The total equivalent coefficient of heat transfer in the outside

K ₁＝7.47×0.42-7.97×0.58+8.6×0.37＝10.949(w/m ².k)

Temperature rise before does not proofread and correct in the outside: Δ Q ₁₁'=995.67/10.949=90.93 (k)

3., high pressure winding average temperature rising: Δ Q ₁=(90.22+90.93)/2=91 (k)

Second kind of method for designing is in the high pressure inboard insulating cylinder to be arranged, and layer, turn-to-turn insulation material contain the method for using under the situation of the glass fiber more than 60%, thereby also be not suitable for the transformer of resin-cast.

The third method for designing: to the eighties in last century, along with the continuous maturation of resin-encapsulate transformer production technology in the world, the temperature rise design also becomes ripe, according to the introduction of external MICAFIL company profile, it is to estimate a temperature rise value earlier, and calculate at loss and the cooling surface area estimated under the temperature rise, simultaneously the heat radiation air flue is converted, again according to hot transfer theory, respectively by heat conduction, convection current and radiation are carried out than accurate Calculation, when the heat flow of calculating and actual heat flow have discrepancy, again estimate temperature rise value, repeat the aforementioned calculation process, match, just think that estimating value is exactly the temperature rise result that should calculate (see external MICAFIL company profile) until heat flow and the actual heat flow calculated.Its high pressure (outer winding) is designed program as follows:

1., estimate and get temperature rise numerical value Δ Q;

2., calculate winding and estimating the every phase loss value P that gets under the temperature rise _k(watt);

3., calculate winding external surface area S ₁(m ²);

4., calculate winding internal surface area S ₂(m ²);

5., average air flue is wide

In the formula: D ₁, D ₂Diameter for the air flue both side surface

6., calculate air flue convection coefficient α=6.8758910 ¹⁰Δ QA ⁴/ l

In the formula: l is coil height (cm)

7., calculate the hot transmitted power Pc that convection current produces

High pressure inner surface convection heat:

High pressure outer surface convection heat:

P ₁=30.01 β S ₁Δ Q/l (watt)

In the formula: $\mathrm{\&beta;}={[0.825+0.387\&CenterDot;{(1.68854\&times;{10}^{-2}\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">l</figure-callout>}}^3\&CenterDot;\mathrm{\&Delta;Q})}^{1/6}]}^2+0.97\frac{\mathrm{<figure-callout\; id="3"\; label="l\; D"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">l</figure-callout>}}{D_{}}$

D ₃Be overall diameter

8., calculate the hot transmitted power that outer winding thermal radiation causes:

High pressure outer surface radiations heat energy:

P _r=2.664910 ^-8S ₁[(Δ Q+313) ⁴-313 ⁴] (watt)

9., the total amount of heat of convection current and radiation generation: ∑ P=P ₁+ P ₂+ P _r(watt)

10., with the gross power ∑ P and every power P mutually of convection current and radiation _kCompare,, think that then above-mentioned to estimate value be exactly the winding average temperature rising,, then estimate again and get temperature rise value, repeat aforementioned calculation if numerical value relatively differs bigger if very approaching, until the gross power of radiation and convection current with estimate value and be close till.

For example: calculate the outer winding average temperature rising of a 1250KVA high pressure:

The high l=815mm P of coil _k=1485.53 (watt)

Internal surface area S ₂=1.3109 (m ²)

External surface area S ₁=1.4517 (m ²)

Estimate and get temperature rise value Δ Q '=73.1 (k)

Average air flue is wide

The air flue convection coefficient

$\mathrm{\&beta;}={[0.825+0.387\&times;{(1.68854\&CenterDot;{10}^{-2}\&CenterDot;{\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">l</figure-callout>}}^3\&CenterDot;\mathrm{\&Delta;Q})}^{1/6}]}^2+0.97\frac{\mathrm{<figure-callout\; id="3"\; label="l\; D"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">l</figure-callout>}}{D_{}}=151.89033$

${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">P</figure-callout>}}_2=30.01\frac{1.3109\&times;78.2\&times;{10}^{-3}}{0.027433}{[{\left(0.060777\mathrm{\&alpha;}\right)}^{-1.5}+{\left({0.57886\mathrm{\&alpha;}}^{0.25}\right)}^{-1.5}]}^{-2/3}$

P ₁=30.01 * β * S ₁* Δ Q/l=593.52 (watt)

P _R2-3=-60.239 (watt)

P _r=2.664910 ^-8S ₁[(Δ Q+313) ⁴+ 313 ⁴]=488.41 (watt)

∑ P=465.55+593.52-60.239+488.41=1487.24 (watt)

∑ P-P _k=+1.711 (watt)

Comparative result illustrates that to get the heat radiation value and the actual loading loss value that calculate under the temperature rise value approaching estimating, and therefore thinks to estimate that to get temperature rise value 73.1k be exactly winding average temperature rising value.

This shows that though the third method for designing evaluation is comparatively approaching, it designs program very loaded down with trivial details, increased very big workload, in case estimate the temperature rise numerical value and the actual value of getting discrepancy has been arranged, computational process just must be made a new start, and to just can draw rational result of calculation repeatedly for several times.Therefore think that the practicality of this cover method is relatively poor.

The 4th kind of method for designing: last century the nineties, the resin-encapsulate transformer is widely popular in the whole world, and constantly technology transfer China, temperature rise is designed program and also is simplified, practicality is stronger.The theory that it had both transmitted according to heat has constantly been summed up the practical experience coefficient again.Its high pressure (outer winding) is designed program following (seeing that document " the theoretical and calculating of dry-type power transformer " Lu Changbai etc. writes 2003.10):

1., calculate coil cooling surface area S (m ²) and inside and outside surface area S ₂, S ₁(m ²)

2., calculate coil primary insulation equivalent thickness E (mm)

3., calculate every phase coil loss P _k(w)

4., calculate winding when net quantity of heat being conducted the winding surface, the average temperature rising Δ Q that the winding layer insulation produces with heat exchange pattern ₁

$\begin{array}{cc}\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="Q"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}_1=\frac{P_k}{S}\&times;50\&times;E& \left(k\right)\end{array}$

5., calculate the heat W that distribute on the inside and outside surface of winding

W=9.3S ₁+ 4.4S ₂(watt)

In the formula: 4.4 and 9.3 are respectively coefficient of heat transfer (the w/d m on inside and outside surface ²)

6., calculate the average temperature rising Δ Q of winding table in the face of stream ₂, promptly be in order to distribute P _kThe heat that produces, winding temperature rise reaches Δ Q ₂Value

$\begin{array}{cc}\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2={\left(\frac{P_k}{W}\right)}^{0.75}\&times;80& \left(k\right)\end{array}$

7., whole temperature rise Δ Q=Δ Q ₁+ Δ Q ₂(k)

For example: calculate a 250KVA high pressure winding temperature rise.

1., high pressure external surface area S ₁=6060 (mm ²)

High pressure internal surface area S ₂=5111 (mm ²)

2., every phase loss 825w 115 ℃ the time

3., layer insulation equivalent thickness

④、 $\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="Q"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}_1=\frac{825}{6060+5111}\&times;50\&times;4.64=17.1K$

5., the high pressure winding table is in the face of stream heat W=225+564=789 (w)

⑥、 $\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="HSA00000225556200011.png"\; state="\{\{state\}\}">Q</figure-callout>}}_2={\left(\frac{825}{789}\right)}^{0.75}\&times;80=82.7K$

⑦、ΔQ＝82.7+17.1＝99.8K

The 4th kind of method for designing also is to draw under the condition of many supposition, and depends on empirical coefficient to a great extent, and it includes following assumed conditions during design:

1., the temperature of every layer conductor is identical, promptly temperature rise at the hottest point is not proofreaied and correct, and in fact hottest spot temperature increases with the increase of coil thickness.

2., think that the winding surface is a plane, in fact the tap position in 75 °～85 ° left and right sides scopes is arranged approximately is not a plane to the high pressure winding, but the different curved surface of thickness.

3., all heats are to distribute in surrounding air by heat conduction, convection current and radiation, and think that the radiation of air flue is compared with convection current between winding, can think that radiation is little as can to ignore.

4., the coefficient of heat transfer 9.3w/dm of outer surface ²Coefficient of heat transfer 4.4w/dm with inner surface ²It is the empirical coefficient that draws by experiment.

5., above-mentioned formula 6. the index n=0.75 in the average temperature rising computing formula in the money also be empirical coefficient, and depend on technology and used insulating material.

Therefore think that though the 4th kind of method for designing simplified a lot, practicality has strengthened, the condition of hypothesis has reduced the accuracy of calculating.

Combine with described, above-mentioned various method for designing all is the forms according to heat conduction, convection current, radiation, consider the influence of air flue simultaneously to radiation, convection current, calculate its referring factor, and introduced empirical coefficient to a great extent and made design result generation deviation, the computational process that has is comparatively numerous and diverse, particularly to the Transformer Winding of larger capacity, and more difficult assurance.

Claims (4)

1. resin-encapsulate Transformer Winding Temperature Rise method for designing is characterized in that: it comprises the manufacture method of actual average temperature rise model and according to the method for actual average temperature rise modelling temperature rise:

1), actual average temperature rise model production method:

1., actual loading test, determine actual average temperature rise Δ Q parameter: the resin-encapsulate Transformer Winding of the big low capacity of difference, different radial thickness, difference being sealed thickness is carried out actual temperature rise test; The fictitious load method that test method allow to adopt according to national standard, and each coil temperature rise when coil midstream crossed rated current and iron core and be rated excitation proofreaies and correct, and calculates the actual average temperature rise Δ Q of every kind of coil;

2., arrangement actual average temperature rise Δ Q parameter: by radial thickness of difference and the different windings of sealing thickness, taxonomic revision actual average temperature rise Δ Q data;

3., determine the apparent area parameter: with winding is that a heating is whole, calculates the heat radiation apparent area S (m of every product winding of above-mentioned correspondence ²);

4., computational load loss P _kParameter: the load loss P during reference temperature that every the product winding that calculates above-mentioned correspondence is selected insulation thermal endurance class _k, comprise resistance loss, eddy current loss and lead-in wire loss; These losses are existing design in the design of transformer process;

5., measuring and calculating apparent heat load q parameter: the apparent heat load q that calculates every product winding of above-mentioned correspondence:

$\begin{array}{cc}q=\frac{P_k}{S}& (w/m^2)\end{array}$

This apparent heat load q value is the thermic load value of apparent area correspondence, and it is the apparent thermic load value of the total radiating effect of reaction heat conduction, convection current, radiation three;

6., on rectangular coordinate, mark the quadrantal points of respectively classify winding apparent thermic load value q and corresponding actual average temperature rise value Δ Q;

7., with all quadrants point on the coordinate, press the difference classification of winding, draw out different radial thickness and the different actual average temperature rise curves of sealing thickness;

8., get one section curve commonly used, the actual average temperature rise curve of this section is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q according to the straight line character of this model;

2), according to the method for actual average temperature rise modelling temperature rise:

1., according to the result of epoxy resin enclosed naturally air-cooled power transformer technical performance calculation of parameter, obtaining winding is the load loss P of the reference temperature of selected insulation thermal endurance class _k(watt), comprise resistance loss, eddy current loss and lead-in wire loss sum;

2., according to the physical dimension of transformer high and low pressure winding, calculate its apparent area S (m ²);

3., measuring and calculating apparent thermic load value q; Q=P _k/ S (W/m ²)

4., according to the linear function relational expression of average temperature rising Δ Q in the actual average temperature rise model and apparent heat load q, calculate the average temperature rising Δ Q of winding; Relatively whether this average temperature rising Δ Q value adheres to specification;

5. or again press apparent heat load q and the corresponding curve of average temperature rising Δ Q in the actual average temperature rise model, look into and be averaged temperature rise Δ Q value, and compare with above-mentioned measuring and calculating value and corresponding class of insulation temperature limit, look above two kinds of average temperature rising Δ Q values and whether adhere to specification;

6., when surpassing the regulation of designing requirement, under the prerequisite of the requirement of satisfying the transformer technology performance parameter, winding is redesigned as if above-mentioned temperature rise value, adjust the wire gauge sectional area and the profile physical dimension of winding, its load loss is reduced, increase area of dissipation, reduce the q value;

7., 1. the parameter of redesign winding is carried out to demonstration 5. again;

8., carry out actual temperature rise test, with the accuracy of checking design;

9., the nargin of temperature rise design: consider that hottest spot temperature is the position of upwards departing from the middle part of winding thickness, and above-mentioned design is meant the average temperature rising of winding, it is not temperature rise at the hottest point, therefore, design must leave certain nargin, and design margin should be littler by about 2～3% than the maximum that allows.

2. a kind of resin-encapsulate Transformer Winding Temperature Rise method for designing according to claim 1 is characterized in that: the actual average temperature rise model production method that the inside of F class F insulation system does not have the gas duct high pressure winding is:

The measuring and calculating inner surface is sealed thickness 2-3mm, outer surface is sealed thickness 4-6mm, layer insulation 0.4-0.6mm, high pressure (outward) the winding actual average temperature rise parameter of radial size 20～40mm all size, on rectangular coordinate, mark the quadrantal points of apparent thermic load value q and corresponding actual average temperature rise value Δ Q, make the actual average temperature rise curve;

Get 45～100K section curve commonly used, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q: Δ Q=0.1q+15 (k) according to the straight line character of this model.

3. a kind of resin-encapsulate Transformer Winding Temperature Rise method for designing according to claim 1, it is characterized in that: the inside of F class F insulation system does not have air flue, appearance is sealed thickness 1-2mm, the actual average temperature rise model production method of radial size 15～35mm low pressure winding:

Measuring and calculating all size low pressure winding actual average temperature rise parameter on rectangular coordinate, marks the quadrantal points of apparent thermic load value q and corresponding actual average temperature rise value Δ Q, making actual average temperature rise curve;

Get 50～100k section curve commonly used, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q: Δ Q=0.125q+12.5 (k) according to the straight line character of this model.

4. a kind of resin-encapsulate Transformer Winding Temperature Rise method for designing according to claim 1, it is characterized in that: there is the wide 12-15mm of air flue the inside of F class F insulation system, appearance is sealed thickness 1-2mm, the actual average temperature rise model production method of air flue both sides radial size 15～30mm low pressure winding:

Measuring and calculating all size low pressure winding actual average temperature rise parameter on rectangular coordinate, marks the quadrantal points of apparent thermic load value q and corresponding actual average temperature rise value Δ Q, making actual average temperature rise curve;

Get 50～100k section curve commonly used, this section actual average temperature rise curve is considered as straight line, make actual average temperature rise model, obtain the linear function of actual average temperature rise value Δ Q and apparent heat load q: Δ Q=0.143q+28.5 (k) according to the straight line character of this model.

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