CN201682423U - Resonant-type precharge circuit for high-voltage frequency converter - Google Patents

Resonant-type precharge circuit for high-voltage frequency converter Download PDF

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Publication number
CN201682423U
CN201682423U CN2010201464481U CN201020146448U CN201682423U CN 201682423 U CN201682423 U CN 201682423U CN 2010201464481 U CN2010201464481 U CN 2010201464481U CN 201020146448 U CN201020146448 U CN 201020146448U CN 201682423 U CN201682423 U CN 201682423U
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China
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phase
current
auxiliary winding
tension supply
circuit
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CN2010201464481U
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Chinese (zh)
Inventor
马永健
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北京利德华福电气技术有限公司
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Abstract

The utility model provides a resonant-type precharge circuit for a high-voltage frequency converter, and is characterized in that the precharge circuit comprises an auxiliary winding, a three-phase capacitor group, a current-limiting resistor group, an AC contactor and a three-phase AC low voltage power supply, wherein the auxiliary winding is arranged on a secondary side of a rectifier transformer; three ends of the three-phase capacitor group are connected with the auxiliary winding, and are connected with the three-phase AC low voltage power supply through the current-limiting resistor group; and the AC contactor is arranged between the current-limiting resistor group and the three-phase AC low voltage power supply. By connecting the three-phase capacitor group in parallel between the auxiliary winding and the current-limiting resistor group, the three-phase capacitor group and each phase line winding on the auxiliary winding form an LC oscillating circuit, so that the LC oscillating circuits formed by the three-phase capacitor group and the auxiliary winding generates exciting current on the rectifier transformer. Therefore, the utility model avoids problems such as high circuit consumption, high cost, low efficiency and the like caused by higher power consumption of exciting current on a current-limiting resistor.

Description

A kind of resonant mode high voltage converter pre-charge circuit
Technical field
The utility model relates to a kind of pre-charge circuit that is used for high voltage converter, particularly a kind ofly produce exciting curent by resonant circuit transformer is carried out excitation, thereby avoided exciting curent on current-limiting resistance, to consume more powerful pre-charge circuit, belonged to the high voltage converter technical field.
Background technology
Development along with power electronic technology, frequency converter is as the product of Development of Power Electronic Technology, every field in national economy is widely used as industries such as metallurgy, petrochemical industry, running water, electric power, and bringing into play more and more important effect, particularly, the application of high-voltage high-power frequency transformator is day by day extensive.
In high voltage converter, (claim power model, current transforming unit again by power cell, as shown in Figure 2) high-voltage high-power frequency transformator (as shown in Figure 1) that constitutes of series connection is as the frequency converter that is fit to China's actual conditions, excellent performance, is subjected to numerous frequency converter production firm, scientific research institutions, engineers and technicians, user's favor.
High-voltage high-power frequency transformator has various topological structures, and length is limit, and this specification is only narrated at many level of the units in series type high voltage converter that is most widely used on market.When the described technology of this patent was applied to the high voltage converter of other topological structures, the narration of its operation principle, topological structure, control method and this specification was identical.
This high voltage converter structure is open in Chinese utility model patent ZL97100477.3.This high voltage converter has a rectifier transformer in grid side, and this rectifier transformer has a plurality of secondary windings, and in order to suppress the harmonic wave to electrical network, these secondary windings usually adopt tortuous winding, reach the effect of phase shift, powers to the power cell of each series connection respectively.Each power cell be 3 mutually the input, single-phase output the voltage-source type frequency converter.
On circuit theory, this rectifier transformer has played the effect of isolating, and each power cell is isolated at input side each other, and like this, because the inverter bridge of power cell is connected mutually at outlet side, the whole current potential (electromotive force) of power cell will improve step by step.
Usually, this rectifier transformer has an auxiliary winding, is the cooling blower power supply of frequency converter.
At present, when high voltage converter powers at high pressure, adopt the method for directly impacting usually, promptly directly closure is the primary cut-out of its power supply.When high pressure powers on, can produce 7 to 10 times to the impulse current of rated current in this way, influence safety, the stable operation of electrical network high-voltage fence.Simultaneously, can produce very big impulse current, influence its useful life dc capacitor in the power cell and rectifying device.
A kind of solution is at the high pressure input side of frequency converter exiting pour current to be installed to suppress circuit.This circuit is made up of current-limiting resistance and high-voltage switch gear (high-pressure vacuum breaker or high-pressure vacuum contactor) in parallel with it.This circuit is connected between the input of high voltage source and high voltage converter.Before high pressure powered on, high-voltage switch gear was in off-state, by current-limiting resistance high voltage converter was charged, after charging is finished, and the closed high switch, charging process finishes.Because this circuit belongs to high-tension circuit, used device is a high tension apparatus, thus cost far above the described circuit of this patent, volume is also much larger than the described circuit of this patent.
Another kind of solution be by low-tension supply and current-limiting resistance to the auxiliary winding power supply of rectifier transformer, on the secondary winding, produce induced voltage by transformer, the dc capacitor of power cell is charged.Along with the carrying out of charging process, bypass the part current-limiting resistance with A.C. contactor gradually, after charging is finished, disconnect charging circuit, the closed high circuit breaker.Though this method can realize with the charging of low-tension supply to frequency converter, but exist some problems: first, because the rated capacity of rectifier transformer complete machine is much larger than the rated capacity of its auxiliary winding, when therefore passing through to assist winding excitatory, the stable state exciting curent is very big, excessive exciting curent can produce excessive voltage drop on current-limiting resistance, if select less A.C. contactor, the resistance of each bypass is bigger, the voltage of then each bypass impact on auxiliary winding is higher, thereby can produce very big impulse current to low-tension supply during at every turn with the A.C. contactor bypass resistance, simultaneously also the direct current in the power cell is had certain impact, if select more A.C. contactor, then cost is higher; The second, if in order to save cost, save the afterbody A.C. contactor, all current-limiting resistances of bypass not before disconnecting charging circuit are then considered ohmically voltage drop, and precharge is inadequate, still has impulse current when high pressure powers on; The 3rd, because excessive exciting curent seriously generates heat resistance, thereby this circuit need adopt high-power resistance, and volume is big, the cost height, and efficient is low.
The utility model content
Main purpose of the present utility model is to solve problems of the prior art, provide a kind of and produce exciting curent carries out excitation to transformer pre-charge circuit by resonant circuit, avoided the transformer excitation electric current to precharge influence, reduced circuit loss to greatest extent, improved system effectiveness, reduced system cost, reduced the impact of power up electrical network and power cell.
Utility model purpose of the present utility model is achieved by following technical proposals:
A kind of resonant mode high voltage converter pre-charge circuit is characterized in that, comprising: auxiliary winding, three-phase condenser bank, current-limiting resistance group, A.C. contactor and three-phase alternating current low-tension supply;
Described auxiliary winding is arranged on the secondary side of rectifier transformer; Three ends of described three-phase condenser bank link to each other with auxiliary winding on the one hand, link to each other with described three-phase alternating current low-tension supply by described current-limiting resistance group on the other hand; Between current-limiting resistance group and three-phase alternating current low-tension supply, be provided with A.C. contactor;
Described three-phase condenser bank is made of a three-phase capacitor or constitutes by a plurality of three-phase capacitors are parallel with one another; Described each three-phase capacitor is interconnected to constitute according to wye connection or triangular form connection by three groups of single-phase electricity containers; Described every group of single-phase electricity container is made of one or more single-phase electricity container parallel connection.
Described three-phase alternating current low-tension supply generally adopts the user scene for the 380V control power supply that high voltage converter provides, and under the situation of conditions permit, selects the identical low-tension supply of high voltage source phase place that inserts with high voltage converter as far as possible.
The induction reactance of the capacitive reactance of described three-phase condenser bank and auxiliary winding self-induction is complementary.
Described current-limiting resistance group can replace with inductive bank.
Between described auxiliary winding and three-phase condenser bank, can also be provided with second A.C. contactor.
The beneficial effects of the utility model are: this resonant type pre-charging circuit is by being parallel with three-phase condenser bank between auxiliary winding and current-limiting resistance group, make each the phase line winding on this three-phase condenser bank and the auxiliary winding form the LC oscillation circuit, thereby rectifier transformer is produced exciting curent by three-phase condenser bank and the formed LC oscillation circuit of auxiliary winding, avoided that to consume the more high-power circuitry consumes that causes on current-limiting resistance big because of exciting curent, the cost height, problem such as efficient is low.
Description of drawings
Fig. 1 is the structure of cell series multi-level converter;
Fig. 2 is typical power cell structure;
Fig. 3 is the circuit diagram of resonant mode high voltage converter pre-charge circuit.
Embodiment
Below in conjunction with drawings and Examples the utility model is further described.
Fig. 3 is the circuit diagram of resonant mode high voltage converter pre-charge circuit.As shown in the figure, the rectifier transformer 1 of high voltage converter includes former limit winding 2 and secondary winding 3.Described resonant mode high voltage converter pre-charge circuit is arranged on the secondary side of rectifier transformer 1, comprising: auxiliary winding 4, three-phase condenser bank 5, current-limiting resistance group 6, A.C. contactor 7 and three-phase alternating current low-tension supply 8.
Described auxiliary winding 4 is arranged on the secondary side of rectifier transformer, and is corresponding with this former limit winding 2.Described three-phase condenser bank 5 is made of a three-phase capacitor or constitutes by a plurality of three-phase capacitors are parallel with one another.Wherein each three-phase capacitor is interconnected to constitute according to wye connection or triangular form connection by three groups of single-phase electricity containers.Every group of single-phase electricity container is made of one or more single-phase electricity container parallel connection.Three ends of described three-phase condenser bank 5 are corresponding with the triple line of auxiliary winding 4 respectively, link to each other with auxiliary winding 4 on the one hand, then link to each other with three-phase alternating current low-tension supply 8 by current-limiting resistance group 6 on the other hand.Described current-limiting resistance group 6 is made of three current-limiting resistances, respectively three phase lines of corresponding auxiliary winding 4.Between current-limiting resistance group 6 and three-phase alternating current low-tension supply 8, be provided with A.C. contactor 7, with disconnection or the closure of controlling this circuit.
Resonant type pre-charging circuit as above-mentioned structure is to be parallel with three-phase condenser bank 5 between auxiliary winding 4 and current-limiting resistance group 6 compared to its main feature of pre-charge circuit that has high voltage converter now, makes that each the phase line winding on this three-phase condenser bank 5 and the auxiliary winding 4 forms LC oscillation circuit.Like this, when high voltage converter carries out precharge, be by current-limiting resistance rectifier transformer to be produced exciting curent no longer just, but rectifier transformer produced exciting curent by three-phase condenser bank 5 and auxiliary winding 4 formed LC oscillation circuits by the three-phase alternating current low-tension supply.Therefore, the resonant type pre-charging circuit designed by the utility model carries out in the charging process rectifier transformer, and the flow through exciting curent of current-limiting resistance of its essence is very little, has so just avoided big to the resistor power requirement in the said prior art in front, the cost height, problem such as efficient is low.
The described three-phase alternating current low-tension supply 8 general 380V control power supplys that adopt the user scene to provide for high voltage converter.This three-phase alternating current low-tension supply 8 both can have been selected the identical low-tension supply of high voltage source phase place that inserts with high voltage converter for use, also can select the different low-tension supply of high voltage source phase place that inserts with high voltage converter for use.But, when this three-phase alternating current low-tension supply 8 is selected the different low-tension supply of the high voltage source phase place that inserts with high voltage converter for use, because there is exiting pour current in transformer, under this situation when high pressure powers on, still may produce impulse current to high-voltage fence, the amplitude of impulse current is disconnected the difference decision of low-voltage three-phase AC low-tension supply voltage-phase constantly by A.C. contactor in the high-voltage fence voltage-phase of high pressure closing moment and the pre-charge circuit.Therefore, in order to reduce the shock effect of impulse current as far as possible, under situation with good conditionsi, should select for use the low-tension supply identical as the three-phase alternating current low-tension supply with the high voltage source phase place of high voltage converter access to high-voltage fence as far as possible.
In addition, in the resonant type pre-charging circuit of the designed structure of the utility model, the exciting curent size of the current-limiting resistance of flowing through is to be determined by the single-phase self-induction of the auxiliary winding single-phase capacitance matching relationship with three-phase condenser bank.
If the single-phase self-induction of star-like equivalence of the auxiliary winding of rectifier transformer is L, the rated frequency of electrical network is f, and then its power frequency induction reactance is
X L=2πfL
If the single-phase appearance value of the star-like equivalence of capacitor is C, then its power frequency capacitive reactance is:
X C = 1 2 πfC
In order to satisfy the parallel resonance condition, induction reactance is got identical numerical value with capacitive reactance.According to the circuitry principle, at this moment, the resultant admittance of inductance, electric capacity parallel branch is:
Y = 1 j X L + 1 - j X C = 0 , (in the formula, j is an imaginary unit)
Total impedance Be infinity, promptly the electric current that flows into from the three-phase alternating current low-tension supply during stable state is zero.
In the dynamic process of charging, because the total impedance of parallel resonance branch road and added independent from voltage on it, constant is infinitely great, so the three-phase alternating current low-tension supply only provides the active current of charging usefulness and the active current that frequency converter no-load loss is used, and need not to provide the exciting curent of transformer.Therefore, according to the designed resonant type pre-charging circuit structure of the utility model, as long as three-phase condenser bank and auxiliary Winding Design coupling are suitable, are not have exciting curent to flow through the current-limiting resistance group in theory, this also is a main purpose of design of the present utility model.
Certainly, in actual device, three-phase condenser bank and auxiliary winding might not mate fully, and there is certain no-load loss in frequency converter, and after therefore charging is finished, the three-phase alternating current low-tension supply will provide a spot of active current.
Therefore, designed current-limiting resistance group 6 main purposes are to provide the electric current restriction for three-phase alternating current low-tension supply 8 in the utility model.The selection principle of current-limiting resistance resistance is in this pre-charge circuit: resistance is not less than the ratio of the pre-charge current that three-phase alternating current low-tension supply phase voltage and its design bear, to guarantee that in pre-charge process the three-phase alternating current low-tension supply overcurrent can not take place from start to finish.
Further reduce the power consumption of charging process if desired, increase under certain condition of cost, can adopt described current-limiting resistance group 6 is replaced to three single-phase inductance, the perhaps mode of a three pole reactor in permission.Under this performance,, therefore can not be reduced to the performance of above-mentioned pre-charge circuit because this current-limiting inductance can not have influence on the resonance relation between the auxiliary winding self-induction of resonant capacitance and transformer.
In addition, in actual use,, disconnect three-phase condenser bank when inserting three-phase condenser bank or electrification in high voltage all the time in the time that electrification in high voltage can being chosen in according to the difference of auxiliary winding rated capacity.The former directly links to each other with three-phase condenser bank by auxiliary winding, is used for the auxiliary bigger situation of coil volume, and this will help further to improve the power factor of frequency converter, and can save an A.C. contactor.The latter is connected with an A.C. contactor 9 between auxiliary winding 4 and three-phase condenser bank 5; it is less to be used for auxiliary coil volume; be not enough to bear for a long time the situation of stable state exciting curent; be connected to the contactor while of three-phase alternating current low-tension supply in disconnection; also disconnect this A.C. contactor 9; change the exciting curent that transformer is provided by the high-pressure side, thereby protection should auxiliary winding 4.
In sum, resonant mode high voltage converter pre-charge circuit that the utility model is designed and control method thereof are by be parallel with three-phase condenser bank between auxiliary winding and current-limiting resistance group, make each the phase line winding on this three-phase condenser bank and the auxiliary winding form the LC oscillation circuit, thereby rectifier transformer is produced exciting curent by three-phase condenser bank and the formed LC oscillation circuit of auxiliary winding, avoided that to consume the more high-power circuitry consumes that causes on current-limiting resistance big because of exciting curent, the cost height, problem such as efficient is low.Any not creative transformation that persons skilled in the art are done based on above-mentioned design philosophy all should be considered as within protection range of the present utility model.

Claims (5)

1. a resonant mode high voltage converter pre-charge circuit is characterized in that, comprising: auxiliary winding, three-phase condenser bank, current-limiting resistance group, A.C. contactor and three-phase alternating current low-tension supply;
Described auxiliary winding is arranged on the secondary side of rectifier transformer; Three ends of described three-phase condenser bank link to each other with auxiliary winding on the one hand, link to each other with described three-phase alternating current low-tension supply by described current-limiting resistance group on the other hand; Between current-limiting resistance group and three-phase alternating current low-tension supply, be provided with A.C. contactor;
Described three-phase condenser bank is made of a three-phase capacitor or constitutes by a plurality of three-phase capacitors are parallel with one another; Described each three-phase capacitor is interconnected to constitute according to wye connection or triangular form connection by three groups of single-phase electricity containers; Described every group of single-phase electricity container is made of one or more single-phase electricity container parallel connection.
2. resonant type pre-charging circuit as claimed in claim 1 is characterized in that: described three-phase alternating current low-tension supply is the identical low-tension supply of high voltage source phase place that inserts with high voltage converter.
3. resonant type pre-charging circuit as claimed in claim 1 is characterized in that: the induction reactance of the capacitive reactance of described three-phase condenser bank and auxiliary winding self-induction is complementary.
4. as claim 1 or 2 or 3 described resonant type pre-charging circuits, it is characterized in that: described current-limiting resistance group replaces with inductive bank.
5. as claim 1 or 2 or 3 described resonant type pre-charging circuits, it is characterized in that: between described auxiliary winding and three-phase condenser bank, also be provided with second A.C. contactor.
CN2010201464481U 2010-03-29 2010-03-29 Resonant-type precharge circuit for high-voltage frequency converter CN201682423U (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101860232A (en) * 2010-03-29 2010-10-13 北京利德华福电气技术有限公司 Resonant type pre-charging circuit for high-voltage frequency converter and control method thereof
CN103078474A (en) * 2012-12-31 2013-05-01 国家电网公司 Soft charging device for high-voltage frequency converter and control method thereof
CN107257200A (en) * 2017-07-25 2017-10-17 顺特电气设备有限公司 The many pulse wave resin-cast phase-shifting commutation transformation systems of Large Copacity

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101860232A (en) * 2010-03-29 2010-10-13 北京利德华福电气技术有限公司 Resonant type pre-charging circuit for high-voltage frequency converter and control method thereof
CN101860232B (en) * 2010-03-29 2012-08-08 北京利德华福电气技术有限公司 Resonant type pre-charging circuit for high-voltage frequency converter and control method thereof
CN103078474A (en) * 2012-12-31 2013-05-01 国家电网公司 Soft charging device for high-voltage frequency converter and control method thereof
CN107257200A (en) * 2017-07-25 2017-10-17 顺特电气设备有限公司 The many pulse wave resin-cast phase-shifting commutation transformation systems of Large Copacity

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AV01 Patent right actively abandoned

Granted publication date: 20101222

Effective date of abandoning: 20120808