CN104198067A - Winding temperature measuring method for transformer - Google Patents

Abstract

The invention discloses a winding temperature measuring method for a transformer. The method includes the steps of 1) collecting the rated current corresponding to every scale of the transformer and performing fitting with a linear equation shown by formula (1) for obtaining linear proportionality coefficients a and b according to the rated current corresponding to every scale of the transformer; 2) collecting the top oil temperature, the high voltage side load current and the current operation scale of the transformer; 3) determining the cooling coefficient m and the winding temperature calculating constant A and B of the transformer according to the cooling mode of the transformer; 4) calculating the winding temperature T of the transformer according to the formula (2). According to the winding temperature measuring method for the transformer, the top oil temperature, the high voltage side load current and the current operation scale of the transformer are collected for simulating to calculate the winding temperature of the transformer on the basis of an automated monitoring system of the transformer, the calculation of the winding temperature is accurate and reliable, a field winding temperature meter can be omitted, the winding temperature failure rate can be decreased, and the maintenance workload and difficulty can be reduced.

Description

A kind of winding temperature measuring method for transformer

Technical field

The present invention relates to the safety monitoring technology field of transformer, be specifically related to a kind of winding temperature measuring method for transformer.

Background technology

Winding temperature is the basis of transformer safe operation, therefore in transformer operational process, and winding temperature that must Real-Time Monitoring transformer.The BWR-04 type winding temperature controller using in electric system is now the meter specially that aims at oil-immersed power transformer design.Transformer Winding temperature T 1 is for transformer top-oil temperature T2 and winding are to oily temperature rise △ T sum (being T1=T2+ △ T), wherein, winding is decided by Transformer Winding electric current to oily temperature rise △ T, and Current Transformer Secondary side electric current is proportional to winding current; The principle of work of winding temperature controller is for adopting the winding temperature of the indirect measuring transformer of " thermal simulation " method, its principle of work is to take out by current transformer the Current Transformer Secondary side electric current being directly proportional to load, after current transformer is adjusted, be input to the heating in winding temperature controller flexible member, the heat that heating produces makes flexible member produce an additional displacement, thereby produce one than the temperature indicated value of the high temperature difference △ T of oil temperature, winding temperature controller is exactly the average indicated value that obtains winding temperature with this round-about way.Digital readout temperature controller is arranged on to be controlled in machine room, transmitter in winding temperature controller is converted into temperature signal (4-20) mA current signal, be input to digital readout temperature controller, operator on duty can observe the temperature of Transformer Winding very easily in pulpit, also can need to export the input of following signal as counter supervisory system according to user simultaneously.The winding temperature gage that oil-filled transformer uses belongs to pressure type thermometric instrument, to measure oil temperature by pressure-type thermometer, utilize TA to measure winding current, current signal is carried out on the basis of oil temperature to machinery by well heater and superpose, instrument reading winding temperature export remote transfer signal on the spot.Controller is generally made up of controller, adaptation, secondary instrument, expense is higher, but practical application is less, generally do not access non electrical quantity control loop, and due to the easy corrosion of mechanical part, potentiometer in controller is more fragile, and table is counted complex structure, expensive, maintenance difficulty is large, has a strong impact on instrument reading and the demonstration of supervisory system temperature on the spot.

Summary of the invention

The technical problem to be solved in the present invention is: for the above-mentioned technical matters of prior art, provide a kind of gear that gathers top-oil temperature, high-pressure side load current and the current operation of transformer based on transformer Automatic monitoring systems can analog computation to go out the winding temperature of transformer, winding temperature calculates accurately reliable, can save on-the-spot around temperature table, reduce winding temperature failure rate, reduce the winding temperature measuring method for transformer of maintenance workload and maintenance difficulties.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is:

For a winding temperature measuring method for transformer, implementation step is as follows:

1) gather rated current corresponding under each gear of transformer, use suc as formula the linear function matching shown in (1) and obtain linear scale factor a and b according to rated current corresponding under each gear;

Ie＝aD+b (1)

In formula (1), Ie represents rated current, and D represents gear, and a and b represent respectively linear scale factor;

2) gear of top-oil temperature, high-pressure side load current and the current operation of collection transformer;

3) determine the cooling ratio m of transformer according to the type of cooling of transformer, determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B;

4) according to the winding temperature T of formula (2) calculating transformer;

T＝t+A(I/(aD+b)) ^B (2)

In formula (2), the winding temperature of T indication transformer, the top-oil temperature of t indication transformer, the high-pressure side load current of I indication transformer, the gear of the current operation of D indication transformer, a and b represent respectively linear scale factor, A and B represent that respectively aforesaid winding temperature calculates constant.

Preferably, described step 3) detailed step as follows:

3.1) determine the cooling ratio m of transformer according to the type of cooling of transformer, in the time that the type of cooling of transformer is a kind of in OA, ONAN, FA, ONAF, OFAF, the cooling ratio m value of described transformer is 0.8; In the time that the type of cooling of transformer is ODAF, the cooling ratio m value of described transformer is 1, and wherein OA represents oil cooling, and ONAN represents oil; FA represents air-cooled, and ONAF represents oil; OFAF represents that forced oil-circulation is air-cooled; ODAF represents that forced oil-circulation guiding is air-cooled;

3.2) determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B, if the cooling ratio m value of transformer is 0.8, winding temperature calculates that constant A is 15.04, B is 1.6; If the cooling ratio m value of transformer is 1, winding temperature calculates that constant A is 13.26, B is 2.

The present invention has following advantage for the winding temperature measuring method of transformer: the present invention is by gathering rated current corresponding under each gear of transformer, obtain linear scale factor a and b according to rated current corresponding under each gear with linear function matching, then gather the top-oil temperature of transformer based on transformer Automatic monitoring systems, the gear of high-pressure side load current and current operation, linear scale factor a and b, winding temperature calculating constant A and B just can calculate the winding temperature of transformer fast, winding temperature calculates accurately reliable, can save on-the-spot around temperature table, reduce winding temperature failure rate, reduce maintenance workload and maintenance difficulties.

Brief description of the drawings

Fig. 1 is the basic procedure schematic diagram of the embodiment of the present invention.

Fig. 2 is that the embodiment of the present invention becomes taking the city of protecting of Yueyang electric company the matched curve schematic diagram that 2# main transformer obtains as example.

Fig. 3 is that the embodiment of the present invention is for the winding temperature curve comparison schematic diagram that protects city change 2# main transformer.

Fig. 4 is the embodiment of the present invention becomes 2# main transformer winding temperature curve comparison schematic diagram for strange ridge.

Fig. 5 is the embodiment of the present invention becomes 1# main transformer winding temperature curve comparison schematic diagram for Lip river king.

Embodiment

As shown in Figure 1, the present embodiment is as follows for the implementation step of the winding temperature measuring method of transformer:

1) gather rated current corresponding under each gear of transformer, use suc as formula the linear function matching shown in (1) and obtain linear scale factor a and b according to rated current corresponding under each gear;

Ie＝aD+b (1)

In formula (1), Ie represents rated current, and D represents gear, and a and b represent respectively linear scale factor.

The city of protecting taking Yueyang electric company becomes 2# main transformer as example, and the relation of protecting rated current corresponding under each gear of city change 2# main transformer is as shown in table 1.Table 1: protect corresponding rated current relation table under each gear that city becomes 2# main transformer.

Gear	1	2	3	4	5	6	7	8
									Electric current	269	273	276	280	284	288	293	297
Gear	9	10	11	12	13	14	15	16
									Electric current	301	306	311	315	321	326	331	337

According to table 1, availablely obtain Ie=4.56D+261.84 suc as formula the linear function matching shown in (1), its corresponding gear curve map is as shown in Figure 2.Known according to this fitting result, the value of linear scale factor a is 4.56, and the value of linear scale factor b is 261.84.

Become 2# main transformer taking the Qi of Yueyang electric company ridge as example, under each gear of strange ridge change 2# main transformer, the relation of corresponding rated current is as shown in table 2.Table 2: corresponding rated current relation table under each gear of strange ridge change 2# main transformer.

Gear	1	2	3	4	5	6	7	8
									Electric current	410.76	415.5	420.3	425.5	430.76	435.5	440.8	446.3
Gear	9	10	11	12	13	14	15	16
									Electric current	451.84	457.6	463.4	469.44	475.6	481.9	485.2	488.5

According to table 2, availablely obtain Ie=5.522D+403.25 suc as formula the linear function matching shown in (1).Known according to this fitting result, the value of linear scale factor a is 5.522, and the value of linear scale factor b is 403.25.

Become 1# main transformer as example taking the Lip river king of Yueyang electric company, it is as shown in table 3 that Lip river king becomes the relation of rated current corresponding under each gear of 1# main transformer.Table 3: Lip river king becomes rated current relation table corresponding under each gear of 1# main transformer.

Gear	1	2	3	4	5	6	7	8
									Electric current	411	416	420	425	430	436	441	446
Gear	9	10	11	12	13	14	15	16
									Electric current	452	458	463	469	476	482	488	495

According to table 3, availablely obtain Ie=5.6691D+402.51 suc as formula the linear function matching shown in (1).Known according to this fitting result, the value of linear scale factor a is 5.6691, and the value of linear scale factor b is 402.51.

2) gear of top-oil temperature, high-pressure side load current and the current operation of collection transformer.

3) determine the cooling ratio m of transformer according to the type of cooling of transformer, determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B.

In the present embodiment, step 3) detailed step as follows:

3.1) determine the cooling ratio m of transformer according to the type of cooling of transformer, in the time that the type of cooling of transformer is a kind of in OA, ONAN, FA, ONAF, OFAF, the cooling ratio m value of described transformer is 0.8; In the time that the type of cooling of transformer is ODAF, the cooling ratio m value of described transformer is 1, and wherein OA represents oil cooling, and ONAN represents oil; FA represents air-cooled, and ONAF represents oil; OFAF represents that forced oil-circulation is air-cooled; ODAF represents that forced oil-circulation guiding is air-cooled;

3.2) determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B, if the cooling ratio m value of transformer is 0.8, winding temperature calculates that constant A is 15.04, B is 1.6; If the cooling ratio m value of transformer is 1, winding temperature calculates that constant A is 13.26, B is 2.

4) according to the winding temperature T of formula (2) calculating transformer;

T＝t+A(I/(aD+b)) ^B (2)

In formula (2), the winding temperature of T indication transformer, the top-oil temperature of t indication transformer, the high-pressure side load current of I indication transformer, the gear of the current operation of D indication transformer, a and b represent respectively linear scale factor, A and B represent that respectively aforesaid winding temperature calculates constant.

In the present embodiment, the concrete derivation principle of formula (2) is as follows:

In GB GB/T 10947-2008, provide oil-filled transformer load directive/guide, under corresponding different loading condition, according to Huan border Wen Du ﹑ Ding layer You Wen ﹑ Bian depressor Sun Hao ﹑ Fu carry Xi Shuo ﹑ Leng but the parameter such as Fang Shi ﹑ winding loss set up the OFAF thermal model of hot-spot temperature of transformer; Directly extend in winding according to light transmitting fiber, measure hot(test)-spot temperature, draw the boundary condition of transformer winding model.

For load factor K, its corresponding temperature rise formula suc as formula shown in (3), temperature drop formula is suc as formula shown in (4).

${\mathrm{\θ}}_h\left(t\right)={\mathrm{\θ}}_a+\mathrm{\Δ}{\mathrm{\θ}}_{\mathrm{or}}+\{\mathrm{\Δ}{\mathrm{\θ}}_{\mathrm{or}}\×{\left[\frac{1+R\×K^2}{1+R}\right]}^x-\mathrm{\Δ}{\mathrm{\θ}}_{\mathrm{or}}\}\×f_1\left(t\right)+\mathrm{\Δ}{\mathrm{\θ}}_{h1}+[{\mathrm{Hg}}_r{K}^y-\mathrm{\Δ}{\mathrm{\θ}}_h]\×f_2\left(t\right)---\left(3\right)$

${\mathrm{\θ}}_h\left(t\right)={\mathrm{\θ}}_a+\mathrm{\Δ}{\mathrm{\θ}}_{\mathrm{or}}+{\left[\frac{1+R\×K^2}{1+R}\right]}^x+\{{\mathrm{\θ}}_{\mathrm{or}}-\mathrm{\Δ}{\mathrm{\θ}}_{\mathrm{or}}\×{\left[\frac{1+R\×K^2}{1+R}\right]}^x\}\×f_3\left(t\right)+{\mathrm{Hg}}_r{K}^y---\left(4\right)$

In formula (3) and formula (4), θ _h(t) hot(test)-spot temperature of expression winding, θ _achanging environment temperature when expression, θ _orrepresent the temperature of top-oil temperature to environment temperature in nominal loss lower fuel tank, △ θ _orrepresent the temperature rise of top-oil temperature to environment temperature in nominal loss lower fuel tank, R represents the ratio of load loss and open circuit loss under rated current, and K represents load factor, and H represents focus coefficient, g _rrepresent the gradient of winding medial temperature to oily medial temperature under rated current, △ θ _h1represent to measure the gradient of hot(test)-spot temperature to top-oil temperature while beginning, △ θ _hrepresent the temperature rise of winding, x represents that the exponential depth that total losses rise top-oil temperature is called for short top layer oil index, and y represents the exponential depth (be called for short winding index) of electric current to winding temperature rise; f ₁(t) represent that steady-state value is the relative recruitment of 1 o'clock top-oil temperature liter, its expression formula is suc as formula shown in (5); f ₂(t) represent that steady-state value is 1 o'clock focus relative recruitment to top-oil temperature gradient, its expression formula is suc as formula shown in (6); f ₃(t) represent that total reduction value is 1 o'clock top-oil temperature liter relative reducing amount to environment temperature gradient, its expression formula is suc as formula shown in (7).

$f_1\left(t\right)=(1-e^{(-t)/(k_{11}\×{\mathrm{\τ}}_0)})---\left(5\right)$

$f_2\left(t\right)=k_{21}\×(1-e^{(-t)/(k_{22}\×{\mathrm{\τ}}_w)})-(k_{21}-1)\×(1-e^{(-t)/({\mathrm{\τ}}_0/k_{22})})---\left(6\right)$

$f_3\left(t\right)=e^{(-t)/(k_{11}\×{\mathrm{\τ}}_0)}---\left(7\right)$

In formula (5), formula (6) and formula (7), k ₁₁﹑ k ₂₂﹑ k ₂₁represent thermal model constant, τ ₀represent average oily time constant, t represents time variable, τ _wrepresent winding time constant.

The OFAF thermal model parameters value of recommending in GB/T 10947-2008 is as follows: k ₁₁=0.5 ﹑ k ₂₂=2 ﹑ k ₂₁=2 ﹑ τ _w=7 ﹑ τ ₀=150 ﹑ H=1.3 ﹑ top layer oil index x=1 and winding index y=1.3 ﹑ R can be with reference to transformer nameplate load loss and open circuit loss parameters etc.By above-mentioned parameter value substitution formula (3) and be optimized, can obtain the expression formula shown in formula (8).

${\mathrm{\θ}}_h={\mathrm{\θ}}_0+\left(\frac{1+{\mathrm{RK}}^{2m}}{1+R}\right)+{\mathrm{Hg}}_r{K}^{2m}---\left(8\right)$

In formula (8), θ _hrepresent the hot(test)-spot temperature of winding, θ ₀represent top-oil temperature in fuel tank, R represents the ratio of load loss and open circuit loss under rated current, and K represents load factor, and H represents focus coefficient, g _rrepresent the gradient of winding medial temperature to oily medial temperature under rated current, the cooling ratio of m indication transformer.

The further simplification of expression formula shown in formula (8) can be obtained to formula (9).

${\mathrm{\θ}}_h={\mathrm{\θ}}_0+\frac{1}{1+R}+(\frac{R}{1+R}+{\mathrm{Hg}}_r)K^{2m}---\left(9\right)$

Consult related transformer nameplate data, under rated current, the ratio R of load loss and open circuit loss is approximately 5～6, for simplifying computation process, the ratio R of load loss under rated current and open circuit loss is considered as to infinity, formula (9) can further be reduced to formula (10).

θ _h＝θ ₀+(1+Hg _r)K ^2m (10)

From formula (10), Hg _rbe the temperature rise of focus winding temperature and main transformer top-oil temperature, wherein the gradient g of winding medial temperature to oily medial temperature under rated current _rcalculating can calculate with reference to JB/T8450-2005 " transformer winding temperature gage " heating temperature rise curve (seeing JB/T8450-2005 accompanying drawing 1) and function expression.

Electric current I s, temperature rise Δ T when known transformer normally moves, the temperature rise function curve of drawing up according to computer mould, then carry out 4 order polynomial matchings, temperature rise Δ T can be expressed as formula (11).

ΔT＝4.0276-19.89Is+53.929Is ²-26.124Is ³+6.6766Is ⁴(Is≤1) (11)

In formula (11), Δ T represents temperature rise, electric current when Is indication transformer normally moves.

Formula (11) is got to the highest second power and be at once reduced to Δ T=18.38Is ², with reference to JB/T8450-2005 " transformer winding temperature gage " heating temperature rise curve (seeing JB/T8450-2005 accompanying drawing 1) and function expression, can draw g _r=18.38, i.e. the gradient g of winding medial temperature to oily medial temperature under rated current _rvalue be 18.38.

According to the model of Transformer Winding temperature controller, primary current I is transferred to the heating current Is of heating element, has conversion coefficient 0.73.Therefore formula (10) can be converted to formula (12).

θ _h＝θ ₀+(1+1.3×18.38)K ^2m＝θ ₀+24.89×(0.73*I/Ie) ^2m (12)

For the different types of cooling, the cooling ratio m value of the transformer of recommending in ieee standard is specifically as shown in table 4.

Table 4: the cooling ratio m value table of transformer under the different types of cooling.

In table 4, OA represents oil cooling, and ONAN represents oil; FA represents air-cooled (forced air is cooling), and ONAF represents oil; OFAF represents that forced oil-circulation is air-cooled; ODAF represents that forced oil-circulation guiding is air-cooled.

Therefore, by the hot(test)-spot temperature θ of winding _hbe expressed as T, by top-oil temperature θ in fuel tank ₀be expressed as t, formula (12) can be converted to the form shown in formula (2).In the time that the cooling ratio m of transformer is 0.8, winding temperature calculates that constant A is 15.04, B is 1.6; If the cooling ratio m value of transformer is 1, winding temperature calculates that constant A is 13.26, B is 2.Therefore formula (2) can be embodied as formula (13) and formula (14) according to the cooling ratio m difference of transformer.

T=t+13.26 (I/ (aD+b)) ^2//the cooling ratio m of transformer is 1 o'clock (13)

T=t+15.04 (I/ (aD+b)) ^1.6//the cooling ratio m of transformer is 0.8 o'clock (14)

In order to verify the accuracy of the winding temperature T that the present embodiment calculates, the present embodiment is by carrying out actual detection and carrying out 24 hours relatively with the winding temperature T that the present embodiment calculates to winding temperature T, obtain curve comparison diagram as shown in Figure 3 for protecting city change 2# main transformer, in 7 o'clock～8 o'clock, minimum winding temperature T is that 41.35 degrees Celsius of corresponding curves are the curve of the winding temperature T that calculates, and in 7 o'clock～8 o'clock, minimum winding temperature T is that 40.78 degrees Celsius of corresponding curves are the curve of the winding temperature T that obtains of actual detection.Become 2# main transformer for strange ridge and obtain curve comparison diagram as shown in Figure 4, in 7 o'clock～8 o'clock, minimum winding temperature T is that 41.69 degrees Celsius of corresponding curves are the curve of the winding temperature T that calculates, and in 7 o'clock～8 o'clock, minimum winding temperature T is that 43.29 degrees Celsius of corresponding curves are the curve of the winding temperature T that obtains of actual detection.Become 1# main transformer for Lip river king and obtain curve comparison diagram as shown in Figure 5, in 5 o'clock～6 o'clock, minimum winding temperature T is that 46.16 degrees Celsius of corresponding curves are the curve of the winding temperature T that calculates, and in 5 o'clock～6 o'clock, minimum winding temperature T is that 47.55 degrees Celsius of corresponding curves are the curve of the winding temperature T that obtains of actual detection.In Fig. 3～Fig. 5, x axle represents the time (unit for hour), and y axle represents temperature (unit for degree Celsius).Known in conjunction with Fig. 3, Fig. 4 and Fig. 5, carry out contrast verification by the curve of winding temperature T and the curve of the winding temperature T that actual detection obtains that the present embodiment is calculated, overall accuracy, the validity that can prove the winding temperature T that the present embodiment calculates are better, and there is higher real-time, can react around warm variation moment.

The above is only the preferred embodiment of the present invention, and protection scope of the present invention is also not only confined to above-described embodiment, and all technical schemes belonging under thinking of the present invention all belong to protection scope of the present invention.It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principles of the present invention, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (2)

1. for a winding temperature measuring method for transformer, it is characterized in that implementation step is as follows:

1) gather rated current corresponding under each gear of transformer, use suc as formula the linear function matching shown in (1) and obtain linear scale factor a and b according to rated current corresponding under each gear;

Ie＝aD+b (1)

In formula (1), Ie represents rated current, and D represents gear, and a and b represent respectively linear scale factor;

2) gear of top-oil temperature, high-pressure side load current and the current operation of collection transformer;

3) determine the cooling ratio m of transformer according to the type of cooling of transformer, determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B;

4) according to the winding temperature T of formula (2) calculating transformer;

T＝t+A(I/(aD+b)) ^B (2)

In formula (2), the winding temperature of T indication transformer, the top-oil temperature of t indication transformer, the high-pressure side load current of I indication transformer, the gear of the current operation of D indication transformer, a and b represent respectively linear scale factor, A and B represent that respectively aforesaid winding temperature calculates constant.

2. the winding temperature measuring method for transformer according to claim 1, is characterized in that described step 3) detailed step as follows:

3.1) determine the cooling ratio m of transformer according to the type of cooling of transformer, in the time that the type of cooling of transformer is a kind of in OA, ONAN, FA, ONAF, OFAF, the cooling ratio m value of described transformer is 0.8; In the time that the type of cooling of transformer is ODAF, the cooling ratio m value of described transformer is 1, and wherein OA represents oil cooling, and ONAN represents oil; FA represents air-cooled, and ONAF represents oil; OFAF represents that forced oil-circulation is air-cooled; ODAF represents that forced oil-circulation guiding is air-cooled;

3.2) determine that according to the cooling ratio m of transformer corresponding winding temperature calculates constant A and B, if the cooling ratio m value of transformer is 0.8, winding temperature calculates that constant A is 15.04, B is 1.6; If the cooling ratio m value of transformer is 1, winding temperature calculates that constant A is 13.26, B is 2.