CN106024308A - Construction method for heating ultra-high voltage transformer oil with low-frequency current short circuit method - Google Patents

Abstract

The invention relates to a construction method for heating ultra-high voltage transformer oil with a low-frequency current short circuit method. According to the method, the ultra-high voltage transformer oil is heated by using the low-frequency current short-circuit method, the working voltage of short circuit heating is reduced by reducing the inductive impedance of a transformer winding so as to shorten temperature rise time and drying treatment time, and research achievements are applied to ultrahigh and extra-high voltage transformer fields to reach the effects of heating and drying the transformer oil. The interior of the winding is heated, an insulator of a transformer body is uniformly heated to an appointed temperature internally, and then moisture inside the insulator is taken out through vacuum pumping and hot-oil circulation treatment, so that a drying effect is reached. According to the short circuit method, the winding is heated from the interior of the body, so that the efficiency can be improved, the heating time is shortened, and the drying effect of the body is superior to an ordinary hot-oil circulation effect. Used equipment and wiring are completely the same as those of a transformer load test.

Description

The construction method of low-frequency current short-circuit method heating ultrahigh voltage transformer oil

Technical field

The present invention principally falls into extra-high voltage and builds transformer technology field, and especially a kind of low-frequency current short-circuit method heating is super The construction method of high-tension transformer oil.

Background technology

In extra-high voltage grid construction, transformator is one of most important equipment, is also the core of whole operation of power networks, and Transformer oil in device body has again cooling, insulation and the effect of extinguishing arc, stablizes transformator or even whole power system all There is vital impact.Within 2009, China Electric Power Research Institute successfully develops power current short-circuit heater and becomes When merit is applied to the dried after 750kV AC transformer scene makes moist and ± 800kV converter power transformer in-site installation Heat drying.But power current short-circuit heater running voltage is high, component devices is many, volume weight is big, transports, install, cloth Put complexity, use extremely inconvenient at substation field, reduce short-circuit method heating transformer advantage efficient, quick.

Summary of the invention

In place of it is an object of the invention to overcome the deficiencies in the prior art, it is provided that a kind of simple in construction, convenient to operate, efficient The construction method of safe and stable reliable low-frequency current short-circuit method heating ultrahigh voltage transformer oil.

The present invention solves it and technical problem is that and take techniques below scheme to realize:

A kind of construction method of low-frequency current short-circuit method heating ultrahigh voltage transformer oil, it is characterised in that: concretely comprise the following steps:

(1) preparation of construction, dispatches from the factory the inquiry of data including transformator and field power supply is specifically investigated；

(2) judge whether to reach the computing formula institute that heater producer provides according to the survey result of field power supply The heat protocol of design, selects the mode of connection；It is required for carrying out safety check after selecting any mode of connection；

1. the situation that power supply is unrestricted, jointly chooses safety margin coefficient Q with producer, and the method provided according to producer determines Heating power, determines the mode of connection；

2. the situation of limited power, first determines heating power according to field power supply practical situation, then analyzes possible connecing Linear formula, finally calculates the equivalent circuit of selected wiring patterns；According to field power supply situation, it is individually for heater and lays power supply Cable；

Now the apparent energy of power supply is:

S_{Depending on}=U × I:

Heater efficiency is η, transformator side draw cos φ, heating power P ':

P '=S_{Depending on}× η × cos φ=142

During heating, electrical source power factor is:

$cos\mathrm{\φ}=\frac{1}{\sqrt{1+{\left(am\right)}^2}}$

According to different transformator leakage reactances and the ratio of winding resistance, determine suitable supply frequency, make a × m span exist Between 0.2～0.5；

(3), according to the test data obtained after previous step wiring, calculate voltage, frequency and electric current；

1. the method provided according to producer determines heating power, and the experimental data according to obtaining calculates；

Transformer coil directly hinders: R1, Rm；Ideal transformer, equivalent circuit parameter: R=R1+k²Rm-2kRm；

K is transformer voltage ratio,

Heating power: P=I_d ²×R_eq

Heating voltage: U=R_eq×I

2., after determining heating power wiring according to field power supply practical situation, the experimental data according to obtaining is counted Calculate；

Transformer coil directly hinders: R1, Rm；Equivalent resistance: R=R1+k²Rm-2kRm, K are transformer voltage ratio

Add thermocurrent:

Heating voltage:

(4) thermometric requires temperature to arrival；

(5) judge whether Machine for adding oil on material power meets heat radiation power；

1. meet heat radiation power and then exit heating；2. it is unsatisfactory for heat radiation power, then reduces heating power to arriving；

(6) deep fat follows bad end；

(7) remove device.

And, step (2) in, after completing wiring, use short circuit loss carry out safety check；

When carrying out short circuit loss test, Secondary Winding short circuit, one time winding applies test voltage, when Secondary Winding reaches volume Determine the power consumption of measuring circuit during electric current.Under the identical mode of connection, for making secondary current be less than rated value, it adds hot merit Rate is necessarily less than the short circuit loss under identical connection type.In order to ensure safety, set certain margin of safety.If safety coefficient For Q, take Q=1.3, then under certain margin of safety Q, the maximum heating power P of the various modes of connection is:The most now Secondary current perunit value

And, step (5) judged result is to be unsatisfactory for heat radiation power, first reduce heater power output, make oil Temperature maintains the most interval interior, avoids because coil insulation is caused damage by long-term big electric current heating as far as possible；

During oil temperature steady state, the heat radiation power of transformator is: Q=F α₂(t_Oil-t_Air), wherein F is transformator surface area, α₂For Air Heat Transfer Coefficient；

In order to maintain temperature stabilization, heating power is: P'=Q

P'=P+P_{Machine for adding oil on material}

Because Machine for adding oil on material heating power can according to temperature automatic adjustment, if: P+P_{Machine for adding oil on material max}≥Q。

Advantages of the present invention and good effect be:

1, the short-circuit method that this method uses is that winding heats from device body inside, can be greatly improved efficiency, shorten heat time heating time, The drying effect of device body is better than common Circulation and Hot Oil Spray effect, and its equipment used and wiring test phase with transformer load completely With.

2, heating compared to power frequency short circuit, low frequency heating technology can overcome its limitation significantly.Extra-high voltage is changed Convertor transformer, during frequency as little as below 1Hz, its impedance voltage is less than 1kV, ensures that peace by simple insulation measures Entirely, it is to avoid substantial amounts of safety custody personnel are the most on duty.Increasing apparatus and compensation device can be omitted simultaneously, greatly reduce Occupation area of equipment, decreases work on the spot amount, improves work efficiency.

3, for UHV, during frequency as little as below 1Hz, its impedance voltage is less than 1kV, by simply Insulation measures ensures that safety, it is to avoid substantial amounts of safety custody personnel are the most on duty.Increasing apparatus and compensation dress simultaneously Put and can omit, greatly reduce occupation area of equipment, decrease work on the spot amount, improve work efficiency.

4, when frequency is close to zero, impedance voltage levels off to constant, and this constant is DCR of Transformer and short circuit electricity The product of stream.Reactive capability is directly proportional to frequency.Therefore the most singly reduce impedance voltage by reduction frequency, also reduce idle Capacity, improve the power factor of heating power supply, it is to avoid uses jumbo compensation device.

5, the present invention is in order to the quality ensureing transformer oil meets regulation and can give full play to the effect that dehumidifying is dried, this Research uses low-frequency current short-circuit method heating extra-high voltage transformer oil, by reducing the induction reactance of Transformer Winding, reduces short circuit and adds The running voltage of heat, to shorten temperature rising-time and dried time, and be applied to achievement in research to surpass, extra-high voltage transformer existing , reach the effect of heat drying transformer oil.

Accompanying drawing explanation

Fig. 1 is elevated pressurization, the mode of connection schematic diagram of middle pressure short circuit；

Fig. 2 is that low-frequency current short-circuit method heats extra-high voltage transformer oil flow chart.

Detailed description of the invention

The invention will be further described below in conjunction with the accompanying drawings and by specific embodiment, and following example are descriptive , it not determinate, it is impossible to limit protection scope of the present invention with this.

The construction method of a kind of low-frequency current short-circuit method heating ultrahigh voltage transformer oil, sees mode of connection shown in accompanying drawing 1, The ultimate principle of short-circuit method is by converter power transformer side winding (usually valve side winding) short circuit, from opposite side winding usually Source side winding) apply alternating voltage, make winding internal flow overcurrent (should control less than its rated current), make internal of winding Heat, is uniformly heated to assigned temperature, then processes through evacuation and Circulation and Hot Oil Spray, take out of absolutely from inside by transformer body insulating Moisture in edge, thus reach dry effect.

Concretely comprise the following steps:

(1) preparation of construction, dispatches from the factory the inquiry of data including transformator and field power supply is specifically investigated；

(2) judge whether to reach the computing formula institute that heater producer provides according to the survey result of field power supply The heat protocol of design, selects the mode of connection；It is required for carrying out safety check after selecting any mode of connection；

1. the situation that power supply is unrestricted, jointly chooses safety margin coefficient Q with producer, and the method provided according to producer determines Heating power, determines the mode of connection；

2. the situation of limited power, first determines heating power according to field power supply practical situation, then analyzes possible connecing Linear formula, finally calculates the equivalent circuit of selected wiring patterns；According to field power supply situation, it is individually for heater and lays power supply Cable；

Now the apparent energy of power supply is:

S_{Depending on}=U × I:

Heater efficiency is η, transformator side draw cos φ, heating power P ':

P '=S_{Depending on}× η × cos φ=142

3. safety check, uses short circuit loss to carry out security verification；

When carrying out short circuit loss test, Secondary Winding short circuit, one time winding applies test voltage, when Secondary Winding reaches volume Determine the power consumption of measuring circuit during electric current.Under the identical mode of connection, for making secondary current be less than rated value, it adds hot merit Rate is necessarily less than the short circuit loss under identical connection type.In order to ensure safety, set certain margin of safety.If safety coefficient For Q, under certain margin of safety Q, the maximum heating power P of the various modes of connection is:

The most now secondary current perunit value

(3), according to the test data obtained after previous step wiring, calculate voltage, frequency and electric current；

1. according to producer provide method determine heating power, it is thus achieved that experimental data calculate；

Now transformer oil heating power is calculated as follows (data from transformator dispatch from the factory laboratory report): sets R, jX and is respectively The equivalent resistance seen into by high-pressure side when pressing off road low-voltage short-circuiting in transformator and induction reactance.

Transformer coil directly hinders: R1, Rm；Ideal transformer, equivalent circuit parameter: R=R1+k²Rm-2kRm

K is transformer voltage ratio,

Now heating power is: P=I_d ²×R_eq

Heating voltage: U=R_eq×I

Utilize transformer short-circuit test data calculating transformer parameter, replace being carried out conversion by ideal transformer model and draw Transformer short-circuit equivalent circuit, utilize experimental data calculate short-circuit parameter:

$R=\frac{P_d}{{I_d}^2}$

Wherein: P_dShort circuit loss, I_dFor short-circuit test electric current.

Ideal transformer model calculating short-circuit parameter:

R=R₁+k²R₂

Wherein: R₁Primary winding D.C. resistance, R₂For secondary coil D.C. resistance；

2. after determining heating power wiring according to field power supply practical situation,

Senior middle school's wiring equivalent resistance ibid, R=R1+k²Rm-2kRm

K is transformer voltage ratio:

During heating, electrical source power factor is:

Suitable supply frequency should be determined according to different transformator leakage reactances and the ratio of winding resistance, makes a × m span Between 0.2～0.5；

The now impedance of equivalent circuit is: Z=R+jX', has again P '=I²× R obtains:

Add thermocurrent:

Heating voltage:

(4) thermometric requires temperature to arrival；

(5) judge whether Machine for adding oil on material power meets heat radiation power；

1., for meeting heat radiation power, when temperature reaches requirement, heater can be exited and then exit heating；

2. for being unsatisfactory for heat radiation power, then heating power is reduced to arriving；

Oil temperature has been reached requirement be considered as reduce heater power output, make oil temperature maintain suitable interval In, avoid because coil insulation is caused damage by long-term big electric current heating as far as possible.

During oil temperature steady state, the heat radiation power of transformator is: Q=F α₂(t_Oil-t_Air), wherein F is transformator surface area, α₂For Air Heat Transfer Coefficient；

In order to maintain temperature stabilization, heating power is: P'=Q

P'=P+P_{Machine for adding oil on material}

Because Machine for adding oil on material heating power can be according to temperature automatic adjustment, so now in order to ensure that temperature stabilization is permissible If: P+P_{Machine for adding oil on material max}≥Q；

(6) deep fat follows bad end；

(7) remove device.

Low frequency short-circuit method heating transformer oil, frequency is the lowest, and power factor is the highest, more has from a point use power Profit.Frequency is direct current time as little as extreme, and direct current can cause the problems such as core sataration, under the conditions of meeting power factor command rationally Heating frequency is set.

Under the different modes of connection, transformator has corresponding maximum allowable heating power, and the power of load loss is different, point The power being fitted in different electric pressure is the most different.When using low frequency short circuit auxiliary heating, there is short low pressure, brachymedial pressure etc. multiple The mode of connection, uses short circuit loss to verify the wiring under certain heating power safely.Carry out under meeting secured premise Wiring is compared.

It was verified that the transformator equivalent resistance calculated through this method and purely ideal model transformator equivalent transformation The equivalent resistance of gained differs up to 30%.In actual applications, more conform to the real data at scene, transformator can be made to heat Device better profits from.

By research, grasp the key technology of low-frequency current short-circuit method heating devices heat transformer oil, innovated one Overlap the heat protocol of oneself, and be successfully applied to Mare Tranquillitatis 500kV substation project, in Yi Li 750kV substation project.Carry High efficiency of construction, it is ensured that construction quality, shortens the duration, accelerates construction speed.At Yi Li 750kV substation project In, use low-frequency current short-circuit method heating devices heat transformer oil technology, by arranging applicable voltage, frequency, it is achieved that Temperature of oil in transformer is heated to the time of 70 degree and was reduced to 18 hours by original 28 hours, saves Financial cost 38200 yuan.

Result of the test is verified

This method be Tianjin Electric Power Transmission & Transformation Engineering Corporation be to adapt to extra-high voltage construction, it is considered under winter cold environment, transformer station executes Work and carry out science and technology item research.

By research, grasp the key technology of low-frequency current short-circuit method heating devices heat transformer oil, innovated one Overlap the heat protocol of oneself, and be successfully applied to Mare Tranquillitatis 500kV substation project, in Yi Li 750kV substation project.Improve Efficiency of construction, it is ensured that construction quality, shortens the duration, accelerates construction speed.

Now as a example by Yi Li 750kV substation project:

The in-site installation of Yi Li 750kV transformator is in mid-October, in order to complete in-site installation and commissioning test smoothly, We take short-circuit method heat run, it is thus achieved that data are as follows:

Table 1 transformer parameter

1, the method provided according to producer determines heating power

Add thermocurrent and be less than the 70%～80% of rated current, typically take the 80% of rated current.Now take specified electricity The high-tension coil of stream minimum is heating coil, and adding thermocurrent is 1132*0.8=907A；

(1) according to elevated pressurization, the mode of connection of low-voltage short-circuiting, now low-pressure side electric currentExceed well over low-voltage rated electric current, inadvisable.

(2) according to elevated pressurization, the mode of connection of middle pressure short circuit, now middle pressure short circuit current Meet security requirement.Therefore, choosing elevated pressurization, the mode of connection of middle pressure short circuit (execute by transformator 750kV coil Add thermocurrent, low pressure 66kV open coil, 220kV short circuit).

Now transformer oil heating power is calculated as follows (data from transformator dispatch from the factory laboratory report):

If the equivalent resistance seen into by high-pressure side when pressing off road low-voltage short-circuiting in R, jX respectively transformator and induction reactance.

Transformer coil directly hinders: R1=0.02828 Ω；Rm=0.03451 Ω (dispatch from the factory from transformator and test report by data Accuse)

Ideal transformer, the short circuit of middle pressure 220, when low pressure 66 is opened a way, the equivalent circuit parameter entered in terms of 750 sides:

R=R1+k²Rm-2kRm=0.410 Ω

K is transformer voltage ratio,

Now heating power is: P=I_d ²×R_eq=907²× 0.410=337kW

In low frequency heating test, power factor λ is typically not less than 0.8, and conservative λ=0.8 that takes calculates herein,

I_{Middle pressure}=I × (765 ÷ 242)=1940≤3766A

Heating voltage: U=R_eq× I=907 × 0.41=371v

The heat protocol of the computing formula design provided according to heater producer is provided, and practical situation is major part Job site Power Supplies Condition does not reaches requirement, it is impossible to provide the biggest power.

2, heating power is determined according to field power supply practical situation

Therefore low-frequency current short-circuit method heating transformer oil should first determine heating power, then analyzes possible connection type, Finally calculate the equivalent circuit of selected wiring patterns, calculate electric voltage frequency, magnitude of voltage, current value, finally carry out safety check.

According to field power supply situation, it is individually for heater and lays service cable.Draft now: low-tension current 300A's Under the conditions of, determine and add thermocurrent and voltage to transformator.

Now the apparent energy of power supply is:

Heater efficiency: η >=95% (full load), takes η=80% during underloading

Transformator side draw cos φ=0.9 item heating power P ':

P '=S_{Depending on}× η × cos φ=142kW

Transformer short-circuit test data (is provided by producer)

Optional Select height short circuit, senior middle school's two kinds of modes of connection of short circuit.

Senior middle school's wiring equivalent resistance is ibid.

R=R1+k²Rm-2kRm=0.410 Ω

K is transformer voltage ratio,

Transformator low current impedance:

Transformer equivalent circuit, the short circuit of middle pressure 220, when low pressure 66 is opened a way, the equivalent circuit parameter entered in terms of 750 sides:

R=R1+k²Rm-2kRm=0.410 Ω

X=83.92

U₁=I (R+jX)

It is f in frequency₁Time, the voltage U that winding is short₁For:

$U_1=I_1(R+j(\frac{f_1}{f}\left)X\right)$

If:Then: U₁=I₁×R(1+jam)

From formula, in the case of electric current is constant, supply frequency is the smaller the better, when for DC source, and winding two ends Voltage and required power supply capacity are minimum.But use DC source heating to have that the transformer core degree of depth is saturated, can only heat The shortcomings such as side winding.Further, after frequency is less than a certain ultimate value, the manufacturing cost of variable-frequency power sources will be significantly increased.Therefore, Consider the various factors such as voltage, power supply capacity, manufacturing cost and determine suitable supply frequency.

Can be deduced by formula, during heating, electrical source power factor is:

$cos\mathrm{\φ}=\frac{1}{\sqrt{1+{\left(am\right)}^2}}$

When a × m takes different value,As shown in table 2:

Cos φ during the different a × m value of table 2

As shown in Table 2, as a × m=0.2, power factor is close to 1, it is not necessary to reactive-load compensation.The most again frequency is reduced Half makes a × m=0.1.Supply voltage and apparent capacity the most only decline about 1.45%.Therefore, should be according to different transformator leakage reactances With the ratio of winding resistance, determine suitable supply frequency, make a × m span between 0.2～0.5.

Take a × m=0.2 to have:

f₁=f × 0.2 × m=50 × 0.2 ÷ 83.96 × 0.410=0.049Hz

The now impedance of equivalent circuit is:

Z=R+jX'=0.41+j0.08

There is again P '=I²× R obtains:

Add thermocurrent:

Heating voltage:

Now low-pressure side electric current: I_{Middle pressure}=I × (765 ÷ 242)=1940≤3766A

Meet the requirement of safety.

But find when voltage rises to 250V when practical operation, add thermocurrent and only have 240A to differ very with value of calculation 614A Far, check that wiring is correct, be connected firmly, no abnormality seen.

3. pair producer provides the correction of calculation

Then transformer short-circuit equivalent circuit is analyzed, to the equivalent resistance that application transformator ideal model obtains Accuracy throws doubt upon.Reporting thus according to delivery test, application load loss test data carry out new equivalent resistance and calculate.

Winding	Test voltage (kV)	Test current (A)	Short-circuit impedance (%)	Short circuit loss (kw)
					High-in	77.67	925.53	21.51	943.2

$R=\frac{P_d}{{I_d}^2}=\frac{943200}{{925.53}^2}=1.01\mathrm{\Ω}$

Now calculate a*m=0.2 and obtain f=0.12Hz

Corresponding heating voltage is: 378V

The corresponding thermocurrent that adds is 373A

In now, pressure surveys electric current is 1240 ＜ 3766A, and middle current voltage is not above allowed rated value, i.e. at safe model In enclosing.

On-the-spot heating state shows, the equivalent circuit that the equivalent resistance using short circuit loss to calculate gained is set up more accords with Close practical situation, it is simple to control heating process.

On-the-spot fire data: voltage: 370V；Electric current: 378A；Heating power: 134kW.

Being calculated gained forcing frequency by this scene is 0.12Hz, and heater design frequency output area is 0.1-0.2Hz, Obviously already close to the limiting frequency of heater, select to be analyzed to heating frequency for this.

$cos\mathrm{\φ}=\frac{1}{\sqrt{1+{\left(am\right)}^2}}$

The power factor user more than 0.9 is just rewarded by system, is intended now the power of an on-the-spot heater Factor is limited in more than 0.95, and now corresponding a*m=0.329, heating frequency is 0.197.

As can be seen here, such a is had may to calculate the gained heating frequency tuning range beyond heater, for this This kind of situation is further analyzed.

Calculate the frequency upper frequency limit higher than device.

Calculating frequency is f1, and upper frequency limit is f2, and the upper limiting frequency that now fetching is put is heating frequency, have m2 < m1, am2 < Am1, cos φ₂＞ cos φ₁。

Power factor is not worse than expected value, therefore when calculating frequency higher than upper limiting frequency, takes in frequency-tuning range Optional frequency is that heating frequency can meet requirement.

When calculating frequency less than lower frequency limit, calculating frequency is f1, and lower-frequency limit is f3, the lower limit frequency that now fetching is put Rate is heating frequency, has m3 > m1, am3 > am1, cos φ₃＜ cos φ₁。

Removing the limit frequency is that heating frequency carries out the high-power transformer short circuits such as power factor checking computations UHV Leakage reactance is about 80～150 with the ratio of winding equivalent resistance, according to different transformer capacities, impedance voltage, switch tap position And winding linked vector graph etc. and different, then have:

$0.16<a*m_3=a*\frac{f_3}{f_N}=a*\frac{0.1}{50}=0.002a<0.3$

Now cos φ ＞ 0.957

Needs can be met.

Safety check will be carried out after choosing any mode of connection.Measure with short circuit loss according to low frequency short-circuit method Concordance in the mode of connection, it is considered to use short circuit loss to carry out security verification.

When carrying out short circuit loss test, Secondary Winding short circuit, one time winding applies test voltage, when Secondary Winding reaches volume Determine the power consumption of measuring circuit during electric current.Under the identical mode of connection, for making secondary current be less than rated value, it adds hot merit Rate is necessarily less than the short circuit loss under identical connection type.In order to ensure safety, set certain margin of safety.If safety coefficient For Q, take Q=1.3, then under certain margin of safety Q, the maximum heating power P of the various modes of connection is:

$P=\frac{P_d}{Q}$

The most now secondary current perunit value(data below is dispatched from the factory from transformator to meet safety requirements Report).

Winding (1 tap)	Test voltage (kV)	Test current (A)	Short-circuit impedance (%)	Short circuit loss (kw)
					High-in	77.67	925.53	21.51	943.2
High-low	53.85	289.43	47.69	187.96
					Medium-low	7.239	870.90	21.38	162.81

According to above formula, take margin of safety Q=1.3, the maximum heating power allowed under the various short-circuit condition of calculating transformer.

Winding connection	High-in	High-low	Medium-low
				The maximum heating power (kw) allowed	725	140	124
Corresponding short circuit current (A)	3301	2095	2095

The heating power P=142 (kW) determined according to Yi Li 750kV substation field condition, may determine that in this approach The optional mode of connection only has height-middle one.

Owing to field power supply condition is good, the power supply capacity at scene need not be considered, it is contemplated that use and allow heating power maximum Short circuit mode heat, use maximum heating power, its voltage, frequency, Current calculation are ibid.

More than calculate the heating process just for transformer oil, oil temperature has been reached to requirement and be considered as reducing heater Power output, make oil temperature maintain suitably interval in, avoid because coil insulation is caused by long-term big electric current heating as far as possible Damage.

During oil temperature steady state, the heat radiation power of transformator is: Q=F α₂(t_Oil-t_Air)

Wherein F is transformator surface area, α₂For Air Heat Transfer Coefficient.

In order to maintain temperature stabilization, heating power is: P'=Q

P'=P+P_{Machine for adding oil on material}

Because Machine for adding oil on material heating power can be according to temperature automatic adjustment, so now in order to ensure that temperature stabilization is permissible If: P+P_{Machine for adding oil on material max}≥Q

F α is taken according to field condition₂=2.5kw/ DEG C

Q=2.5* (65+5)=175kW

The maximum heating power of known on-the-spot oil filter is 200kW, therefore when temperature reaches requirement, can exit and add hot charging Put.

By field test data it can be seen that on the premise of transformator has Insulation, short-circuit method heating is greatly shortened The process time of Circulation and Hot Oil Spray, improve oil immersion effect, ensured that the oil temperature of commissioning test, the effect of short-circuit method heating are Ideal.

Although disclosing embodiments of the invention and accompanying drawing for the purpose of illustration, but those skilled in the art can managing Solving: without departing from the present invention and spirit and scope of the appended claims, various replacements, to change and modifications be all possible, Therefore, the scope of the present invention is not limited to embodiment and accompanying drawing disclosure of that.

Claims (3)

1. the construction method of a low-frequency current short-circuit method heating ultrahigh voltage transformer oil, it is characterised in that: concretely comprise the following steps:

(1) preparation of construction, dispatches from the factory the inquiry of data including transformator and field power supply is specifically investigated；

(2) judge whether can reach designed by the computing formula that heater producer provides according to the survey result of field power supply Heat protocol, select the mode of connection；It is required for carrying out safety check after selecting any mode of connection；

1. the situation that power supply is unrestricted, jointly chooses safety margin coefficient Q with producer, and the method provided according to producer determines heating Power, determines the mode of connection；

2. the situation of limited power, first determines heating power according to field power supply practical situation, then analyzes possible wiring shape Formula, finally calculates the equivalent circuit of selected wiring patterns；According to field power supply situation, it is individually for heater and lays power supply electricity Cable；

Now the apparent energy of power supply is:

Heater efficiency is η, transformator side draw cos φ, heating power P ':

P '=S_{Depending on}× η × cos φ=142

During heating, electrical source power factor is:

$cos\mathrm{\&phi;}=\frac{1}{\sqrt{1+{\left(am\right)}^2}}$

According to different transformator leakage reactances and the ratio of winding resistance, determine suitable supply frequency, make a × m span 0.2～ Between 0.5；

(3), according to the test data obtained after previous step wiring, calculate voltage, frequency and electric current；

1. the method provided according to producer determines heating power, and the experimental data according to obtaining calculates；

Transformer coil directly hinders: R1, Rm；Ideal transformer, equivalent circuit parameter: R=R1+k²Rm-2kRm；0.410K is transformation Device no-load voltage ratio,

Heating power: P=I_d ²×R_eq

Heating voltage:

2., after determining heating power wiring according to field power supply practical situation, the experimental data according to obtaining calculates；

Transformer coil directly hinders: R1, Rm；Equivalent resistance: R=R1+k²Rm-2kRm, K are transformer voltage ratio

Add thermocurrent:

Heating voltage:

(4) thermometric requires temperature to arrival；

(5) judge whether Machine for adding oil on material power meets heat radiation power；

1. meet heat radiation power and then exit heating；2. it is unsatisfactory for heat radiation power, then reduces heating power to arriving；

(6) deep fat follows bad end；

(7) remove device.

The construction method of low-frequency current short-circuit method the most according to claim 1 heating ultrahigh voltage transformer oil, its feature exists In: step (2) in, after completing wiring, use short circuit loss to carry out safety check；

When carrying out short circuit loss test, Secondary Winding short circuit, one time winding applies test voltage, when Secondary Winding reaches specified electricity The power consumption of measuring circuit during stream.Under the identical mode of connection, for making secondary current be less than rated value, its heating power must Must be less than the short circuit loss under identical connection type.In order to ensure safety, set certain margin of safety.If safety coefficient is Q, Take Q=1.3, then under certain margin of safety Q, the maximum heating power P of the various modes of connection is:The most now secondary electricity Stream perunit value

The construction method of low-frequency current short-circuit method the most according to claim 1 heating ultrahigh voltage transformer oil, its feature exists In: step (5) judged result is to be unsatisfactory for heat radiation power, first reduce heater power output, make oil temperature maintain suitable When, in interval, avoiding because coil insulation is caused damage by long-term big electric current heating as far as possible；

During oil temperature steady state, the heat radiation power of transformator is: Q=F α₂(t_Oil-t_Air), wherein F is transformator surface area, α₂For Air Heat Transfer Coefficient；

In order to maintain temperature stabilization, heating power is: P'=Q

P'=P+P_{Machine for adding oil on material}

Because Machine for adding oil on material heating power can according to temperature automatic adjustment, if: P+P_{Machine for adding oil on material max}≥Q。