CN203747660U - Sinusoidal wave modulation-based large-scale power transformer low-frequency heating device - Google Patents
Sinusoidal wave modulation-based large-scale power transformer low-frequency heating device Download PDFInfo
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- CN203747660U CN203747660U CN201420124016.9U CN201420124016U CN203747660U CN 203747660 U CN203747660 U CN 203747660U CN 201420124016 U CN201420124016 U CN 201420124016U CN 203747660 U CN203747660 U CN 203747660U
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Abstract
A sinusoidal wave modulation-based large-scale power transformer low-frequency heating device is provided. The sinusoidal wave modulation-based large-scale power transformer low-frequency heating device includes a phase-shifting transformer, an alternating current-alternating current frequency conversion device and a heated transformer which are connected with one another sequentially; a port at one side of the heated transformer is short circuited; the alternating current-alternating current frequency conversion device comprises two three-phase bridge rectifiers which are in reverse parallel connection; and the alternating current-alternating current frequency conversion device further comprises a frequency converter sinusoidal wave control unit, an output signal acquisition module and a frequency conversion power source main loop, wherein the frequency converter sinusoidal wave control unit comprises a sinusoidal wave modulation unit, a feedback control module and a conduction angle triggering controller. According to the sinusoidal wave modulation-based large-scale power transformer low-frequency heating device of the utility model, the two three-phase bridge rectifiers are in reverse parallel connection, and a thyristor natural current commutation mode is adopted to realize frequency conversion. Thus, the sinusoidal wave modulation-based large-scale power transformer low-frequency heating device has the advantages of stable and reliable operation, no direct current link, simple main loop, and high frequency-conversion efficiency.
Description
Technical field
The utility model relates to the test of large-scale power transformer, is a kind of large-scale power transformer low frequency heater based on sine wave modulation specifically.The high-power transformer of mentioning in the utility model refers to that electric pressure is 500kV and above power transformer, comprises converter transformer.
Background technology
Large-scale power transformer volume is large, Heavy Weight, and finished product transport is very difficult.Therefore, in power engineering, tend to adopt fractionation transport, field-installed construction mode.In the process of transformer field assembling, insulating part may make moist because being exposed in air, before therefore putting into operation after installation, need carry out heat treated to transformer, inner moisture is discharged, improve the dry tenacity of insulating part, and then raising electrical strength, ensure safe operation.Transformer, after disintegration overhaul, need carry out heat drying processing equally.The in the situation that of weather conditions severe cold, large-scale power transformer puts into operation, and also needs transformer to be heated at the temperature of regulation and can to put into operation.
The method of existing transformer heat drying processing has: Circulation and Hot Oil Spray or spray, hot air circulation, vacuumize, " short-circuit method " etc.
Circulation and Hot Oil Spray, hot air circulation, boulton process belong to outside heating method, low, the consuming time length of efficiency of heating surface when on-the-spot application, in the situation that ambient temperature is lower, are difficult to reach good heating effect.Carry out transformer dry heating as mentioned in the notification number patent that is CN101692402A with vacuum tank, but the method is only applicable in transformer manufacturing building, is difficult to on-the-spot application.
" short-circuit method " is to make the inner short circuit current flow of Transformer Winding, from the inner heating of device body, can greatly raise the efficiency, and shortens heating time.Utilize short-circuit method from inner heating transformer oil as announced in the patent of notification number CN103151720A.But " short-circuit method " mainly adopts power frequency at present, and power supply not only will be provided for the active power of heating in winding, the idle of transformer consumption also will be provided, the power supply capacity needing is large, the on-the-spot difficulty that uses; If employing capacitance compensation, can make heater huge, inconvenience is mobile, is difficult to on-the-spot application.
Therefore, based on short-circuit method, the new technology that the research transformer efficiency of heating surface is higher, device volume is less, to shorten transformer installation period, improve transformer field heat drying effect, improve transformer insulation state, ensure that transformer safe operation is significant, can bring great economic benefit.
Summary of the invention
Technical problem to be solved in the utility model is to address the above problem, and a kind of large-scale power transformer low frequency heater based on sine wave modulation is provided.
The described large-scale power transformer low frequency heater based on sine wave modulation, it is characterized in that: comprise phase shifting transformer and AC-AC converter plant, the output of described phase shifting transformer connects the input of described AC-AC converter plant, the output of AC-AC converter plant is connected with a side ports of heated transformer, for heated transformer being carried out to low frequency heating in the time being heated the opposite side port short circuit of transformer;
Described AC-AC converter plant comprises the sinusoidal wave control unit of frequency converter, output signal acquisition module and variable frequency power supply major loop, described variable frequency power supply major loop is provided with the three-phase commutation bridge that two reverse parallel connections connect, described three-phase commutation bridge is by semiconductor switch control rectification output signal, and the sinusoidal wave control unit of described frequency converter comprises sine wave modulation unit, feedback control module and angle of flow trigger controller;
The rectifier bridge of described variable frequency power supply major loop is controlled in the output of the sinusoidal wave control unit of described frequency converter, by this rectifier bridge sine wave output voltage to heated transformer, described output signal acquisition module feeds back to the signals collecting of heated transformer the feedback control module of the sinusoidal wave control unit of described frequency converter, described angle of flow trigger controller receives the signal of described sine wave modulation unit and the output signal of feedback control module, controls the rectifier bridge semiconductor switch of variable frequency power supply major loop.
On described heated transformer, be provided with temperature sensor, described sine wave modulation unit is provided with frequency adjustment module, is heated the electric current of transformer according to the feedback signal of temperature sensor by the control of regulating frequency adjustment module.
The sinusoidal wave control unit of described frequency converter is provided with protection control circuit, for described control variable frequency power supply major loop and angle of flow trigger controller are limited and protected.
The utility model utilizes low-frequency current heating, and compared with power frequency heating, while exporting equal heating current, the capacity of required heater can significantly reduce; And low frequency heats without carrying out reactive power compensation.In to transformer heating process, the iron core of transformer is difficult for saturated, and from the inner heating of Transformer Winding, heating is fast, efficiency is high, and device volume little, lightweight, be convenient to movable application.
Low-frequency ac power is made up of " hand over-hand over " translation circuit, adopts two groups of bridge rectifier reverse parallel connections to form.The positive negative direction of two groups of bridge-type all controlled rectifier circuit periodical exchange conducting, realizes the alternation output of voltage.Every group of rectifier bridge forms by 6 thyristors, by the angle of flow of controlling each thyristor, the output voltage of circuit regulated.
The control mode of low-frequency ac power adopts sine wave modulation, and sine wave modulation is by the angle of flow of dynamic each thyristor of control, makes the voltage approaches sinusoidal variations at load two ends.While adopting sine wave modulation, low-frequency ac power output voltage is sinusoidal wave, and electric current is close to sine wave, and thyristor switch frequency is high, inefficiency, power factor average out to 0.6.Control circuit sends control signal, by sinusoidal rule, trigger delay angle α is debugged.In front half period, allow the α of P be reduced to gradually 0 ° by sinusoidal rule by 90 °, then increase to gradually 90 °, can make like this output voltage increase to gradually from zero by sinusoidal rule the highest, then reduce to gradually zero; In rear half period, allow the Trigger Angle of N be reduced to gradually 0 ° by sinusoidal rule by 90 ° equally, then increase to gradually 90 °.Making output voltage be sinusoidal wave changes.
The utility model advantage is compared to existing technology:
(1) the utility model is directly by two rectifier bridge reverse parallel connections, adopts thyristor nature commutation mode to realize frequency conversion, and working stability, reliable does not have DC link, major loop simple, and conversion efficiency is high.And " friendship orthogonal " is though variable frequency power supply technology maturation, but still there is defect for Transformer on Site heating, be mainly manifested in following two aspects: the one, " friendship orthogonal " is made up of rectification circuit, filter capacitor, inverter circuit, and there is DC link in centre, circuit complexity, stability is low; The 2nd, " friendship orthogonal " variable frequency power supply is to avoid the Short-circuit Working Condition that occurs that upper and lower bridge arm is straight-through, can Dead Time be set to switch element, causes conversion efficiency to reduce, and under equal installed capacity, can reduce the transformer field efficiency of heating surface; The 3rd, " friendship orthogonal " variable frequency power supply control and protection is more complicated, and the on-the-spot electromagnetic environment of construction of transformer substation and power quality are comparatively severe, can cause potential safety hazard, once go wrong, just may bring heavy losses.Therefore, the variable frequency power supply of utilizing two groups of direct reverse parallel connections of rectifier bridge the utility model proposes, adds and hankers having more significant advantage in Transformer on Site short circuit.
(2) adopt low frequency heating means, utilize Transformer Winding short circuit current to heat from inside, the efficiency of heating surface is high, drying effect good, consuming time short.Can coordinate traditional method such as Circulation and Hot Oil Spray, vacuumize to use together, further improve the efficiency of heating surface, shorten heating time.
(3) because heating power supply frequency is lower, impedance loop corner connection is bordering on 0 degree, and in power output, idle content is very little.Therefore, export in the situation of equal electric current, the output capacity of low frequency heating power supply significantly reduces compared with power frequency, and the volume weight of heater reduces greatly, on-the-spot easy to use, conveniently moving, has a extensive future.
Brief description of the drawings
Fig. 1 is the loop connection diagram of the utility model heater,
Fig. 2 is control loop schematic diagram of the present utility model.
In figure: 1-three-phase alternating-current supply, 2-phase shifting transformer, 3-AC-AC converter plant; 4-heated transformer; the sinusoidal wave control unit of 5-frequency converter, 6-variable frequency power supply major loop, 7-output signal acquisition module; 8-sine wave modulation unit; 9-feedback control module, 10-angle of flow trigger controller, 11-protection control circuit; 12-P organizes rectifier bridge, and 13-N organizes rectifier bridge.
Embodiment
Below in conjunction with embodiment and accompanying drawing, the utility model is further illustrated: as shown in Fig. 1,2, the described large-scale power transformer low frequency heater based on sine wave modulation, comprise phase shifting transformer 2 and AC-AC converter plant 3, the output of described phase shifting transformer 2 connects the input of described AC-AC converter plant 3, the output of AC-AC converter plant 3 is connected with a side ports of heated transformer 4, for heated transformer being carried out to low frequency heating in the time being heated the opposite side port short circuit of transformer 4.
Described AC-AC converter plant 3 comprises the sinusoidal wave control unit 5 of frequency converter, output signal acquisition module 7 and variable frequency power supply major loop 6, described variable frequency power supply major loop 6 is provided with the three-phase commutation bridge that two reverse parallel connections connect, described three-phase commutation bridge is by semiconductor switch control rectification output signal, and the sinusoidal wave control unit 5 of described frequency converter comprises sine wave modulation unit 8, feedback control module 9 and angle of flow trigger controller 10.
The rectifier bridge of described variable frequency power supply major loop 6 is controlled in the output of the sinusoidal wave control unit 5 of described frequency converter, by this rectifier bridge sine wave output voltage to heated transformer 4, described output signal acquisition module 7 feeds back to the signals collecting of heated transformer 4 feedback control module 9 of the sinusoidal wave control unit 5 of described frequency converter, described angle of flow trigger controller 10 receives the signal of described sine wave modulation unit 8 and the output signal of feedback control module 9, controls the rectifier bridge semiconductor switch of variable frequency power supply major loop 6.
On described heated transformer 4, be provided with temperature sensor, described sine wave modulation unit 8 is provided with frequency adjustment module, to the rated current that is heated transformer, be heated the electric current of transformer by sine wave modulation unit 8 regulation output FREQUENCY CONTROL output currents by the control of regulating frequency adjustment module according to the feedback signal of temperature sensor.
The utility model, on the basis of said apparatus, utilizes low-frequency current heating, and compared with power frequency heating, while exporting equal heating current, the capacity of required heater can significantly reduce; And low frequency heats without carrying out reactive power compensation.Low-frequency ac power is as transformer field heating power supply, and its input is powered by 380V station electricity consumption; In heated Transformer Winding, flow through the heating of low frequency short circuit current, and then heating transformer dielectric, reach the dry effect of tide.Further, change output voltage and the frequency of low-frequency ac power, can regulate the heating power of Transformer Winding; By measuring transformer winding temperature and transformer top-oil temperature, can Real-Time Monitoring the temperature rise of heated transformer.
In the time that tested transformer short-circuit electric current is larger; in the middle of using power supply and low frequency heating power supply input at 380V station, be connected in series a phase shifting transformer; be used for raising on the one hand input voltage; further improve the output voltage of low frequency heating power supply; phase shifting transformer suppresses the effect of harmonic wave in addition on the other hand, and protection electrical network is not subject to the humorous wave interference of variable frequency power supply.
Described low-frequency ac power is made up of " hand over-hand over " translation circuit, adopts two groups of bridge rectifier reverse parallel connections to form.The positive negative direction of two groups of bridge-type all controlled rectifier circuit periodical exchange conducting, realizes the alternation output of voltage.Every group of rectifier bridge forms by 6 thyristors, by the angle of flow of controlling each thyristor, the output voltage of circuit regulated.
The control mode of AC-AC converter plant adopts sine wave modulation, and sine wave modulation is by the angle of flow of dynamic each thyristor of control, makes the voltage approaches sinusoidal variations at load two ends.While adopting sine wave modulation, low-frequency ac power output voltage is sinusoidal wave, and electric current is close to sine wave, and thyristor switch frequency is high, inefficiency, power factor average out to 0.6.
In heating process, reduce gradually frequency, increase the output current of low frequency heating power supply.Utilize current transformer and waveform analyzer to monitor this output current, in the time that output current reaches heated transformer rated short circuit current, holding frequency is constant, and can make outputting current steadily is transformer rated short circuit current.
In heating process, need to monitor winding temperature.When not having in heated transformer when oil-filled, the winding temperature of transformer should not exceed 95 DEG C.In the time having oil in heated transformer, should in heating process, monitor top-oil temperature; For preventing the too high insulation degradation that causes of oil temperature, top-oil temperature should not exceed 85 DEG C.
Winding mean temperature can be determined by through type (4).
In formula (4), R '
1and R '
2d.C. resistance while being respectively 80 DEG C of tested transformer both sides windings.R is under current state, the measured value of DCR of Transformer.
Claims (3)
1. the large-scale power transformer low frequency heater based on sine wave modulation, it is characterized in that: comprise phase shifting transformer (2) and AC-AC converter plant (3), the output of described phase shifting transformer (2) connects the input of described AC-AC converter plant (3), the output of AC-AC converter plant (3) is connected with a side ports of heated transformer (4), for heated transformer being carried out to low frequency heating in the time being heated the opposite side port short circuit of transformer (4);
Described AC-AC converter plant (3) comprises the sinusoidal wave control unit of frequency converter (5), output signal acquisition module (7) and variable frequency power supply major loop (6), described variable frequency power supply major loop (6) is provided with the three-phase commutation bridge that two reverse parallel connections connect, described three-phase commutation bridge is by semiconductor switch control rectification output signal, and the sinusoidal wave control unit of described frequency converter (5) comprises sine wave modulation unit (8), feedback control module (9) and angle of flow trigger controller (10);
The rectifier bridge of described variable frequency power supply major loop (6) is controlled in the output of the sinusoidal wave control unit of described frequency converter (5), by this rectifier bridge sine wave output voltage to heated transformer (4), described output signal acquisition module (7) feeds back to the signals collecting that is heated transformer (4) feedback control module (9) of the sinusoidal wave control unit of described frequency converter (5), described angle of flow trigger controller (10) receives the signal of described sine wave modulation unit (8) and the output signal of feedback control module (9), control the rectifier bridge semiconductor switch of variable frequency power supply major loop (6).
2. the large-scale power transformer low frequency heater based on sine wave modulation according to claim 1, it is characterized in that: on described heated transformer (4), be provided with temperature sensor, described sine wave modulation unit (8) is provided with frequency adjustment module, is heated the electric current of transformer according to the feedback signal of temperature sensor by the control of regulating frequency adjustment module.
3. the large-scale power transformer low frequency heater based on sine wave modulation according to claim 1; it is characterized in that: the sinusoidal wave control unit of described frequency converter (5) is provided with protection control circuit (11), for described control variable frequency power supply major loop (6) and angle of flow trigger controller (10) are limited and protected.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420124016.9U CN203747660U (en) | 2014-03-19 | 2014-03-19 | Sinusoidal wave modulation-based large-scale power transformer low-frequency heating device |
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| CN201420124016.9U CN203747660U (en) | 2014-03-19 | 2014-03-19 | Sinusoidal wave modulation-based large-scale power transformer low-frequency heating device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105071260A (en) * | 2015-08-14 | 2015-11-18 | 中广核工程有限公司 | Insulating property processing method for nuclear power station main transformer after overdue of onsite warehousing |
| CN106841875A (en) * | 2017-03-01 | 2017-06-13 | 国家电网公司 | Three-Phase Distribution Transformers temperature rise test system and method based on alternating low frequency heating |
| CN107167515A (en) * | 2017-07-18 | 2017-09-15 | 中国石油化工股份有限公司 | A kind of control method of quick constant current |
| CN113357901A (en) * | 2021-04-30 | 2021-09-07 | 浙江大唐乌沙山发电有限责任公司 | Automatic drying device and automatic drying method for insulated damp |
-
2014
- 2014-03-19 CN CN201420124016.9U patent/CN203747660U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105071260A (en) * | 2015-08-14 | 2015-11-18 | 中广核工程有限公司 | Insulating property processing method for nuclear power station main transformer after overdue of onsite warehousing |
| CN106841875A (en) * | 2017-03-01 | 2017-06-13 | 国家电网公司 | Three-Phase Distribution Transformers temperature rise test system and method based on alternating low frequency heating |
| CN106841875B (en) * | 2017-03-01 | 2024-05-03 | 国家电网公司 | Three-phase distribution transformer temperature rise test system and method based on alternating-current low-frequency heating |
| CN107167515A (en) * | 2017-07-18 | 2017-09-15 | 中国石油化工股份有限公司 | A kind of control method of quick constant current |
| CN113357901A (en) * | 2021-04-30 | 2021-09-07 | 浙江大唐乌沙山发电有限责任公司 | Automatic drying device and automatic drying method for insulated damp |
| CN113357901B (en) * | 2021-04-30 | 2022-09-23 | 浙江大唐乌沙山发电有限责任公司 | Automatic drying device and automatic drying method for insulated damp |
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Granted publication date: 20140730 |