CN109599837B - Voltage compensation type transformer excitation inrush current suppression device - Google Patents
Voltage compensation type transformer excitation inrush current suppression device Download PDFInfo
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- CN109599837B CN109599837B CN201910017408.2A CN201910017408A CN109599837B CN 109599837 B CN109599837 B CN 109599837B CN 201910017408 A CN201910017408 A CN 201910017408A CN 109599837 B CN109599837 B CN 109599837B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/045—Differential protection of transformers
- H02H7/0455—Differential protection of transformers taking into account saturation of current transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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Abstract
The invention relates to a voltage compensation type transformer magnetizing inrush current suppression device which is used for suppressing magnetizing inrush current and comprises an alternating current power supply V1, an equivalent direct current compensation voltage source Vc, a first bridge full-wave rectifier B1 and a direct current reactor L1, wherein a first input end of the first bridge full-wave rectifier B1 is connected with the alternating current power supply V1, a second input end of the first bridge full-wave rectifier B1 is connected with a primary side of a main transformer T2, and the equivalent direct current compensation voltage source Vc takes the alternating current power supply V1 as input and is connected in series with the direct current reactor L1 and then connected between a first output end and a second output end of the first bridge full-wave rectifier B1 in parallel. Compared with the prior art, the invention has the advantages of no influence on the system, no need of an additional control detection circuit, voltage loss compensation, simple structure, high reliability and the like.
Description
Technical Field
The invention relates to the field of power systems, in particular to a voltage compensation type transformer magnetizing inrush current suppression device.
Background
The power transformer is used as a key main device for power transmission and transformation, and the reliable and stable operation of the power transformer is very important for the effective transmission of electric energy. When the transformer is in steady-state operation, the exciting current of the transformer is only 1% -2% of the rated current, but when the transformer is put into no-load operation or the voltage of an external fault removal system is recovered, large exciting inrush current is easy to generate, and the peak value of the exciting inrush current can reach several times to dozens of times of the rated current. The large magnetizing inrush current may cause the differential protection malfunction, so that the insulation of the transformer is aged, and the structure of the transformer and the adjacent equipment thereof are greatly impacted, thereby affecting the reliable and stable operation of the transformer.
Because the magnetizing inrush current brings various adverse effects to the operation of the transformer, various methods for reducing the magnetizing inrush current are proposed, and can be divided into two categories in general: an internal control method, namely starting from the excitation principle of a transformer core, and achieving the purpose of reducing the excitation inrush current by changing the internal structure of the transformer; and an external control method, namely a suppression circuit or a control method is adopted outside the transformer to reduce the magnetizing inrush current. At present, the internal control method includes a virtual air gap method and a distribution method for changing primary and secondary windings of a transformer, but the internal structure of the transformer needs to be changed, the design and manufacturing difficulty of the transformer is increased, and the method is not adopted generally. The external control method comprises a method of adding a capacitor on the low-voltage side of the transformer, a switch closing control method, an interpolation resistance method and a series resistance method. The method of adding a capacitor at the low-voltage side, the method of connecting resistors in series and the method of inserting resistors in series all need to add extra switches and control systems in a circuit, and the suppression device can be guaranteed to exit in time after the magnetizing inrush current is suppressed; the switch closing control method needs to add a detection and control circuit, and the control is complex, and the accuracy is difficult to master.
Therefore, there is a need for an inrush current suppression device that does not affect the stable operation of the system, and does not require additional switches and detection control circuits, thereby ensuring stable and reliable operation of the transformer.
Disclosure of Invention
The present invention aims to overcome the defects of the prior art and provide a voltage compensation type transformer magnetizing inrush current suppression device.
The purpose of the invention can be realized by the following technical scheme:
a voltage compensation type transformer magnetizing inrush current suppression device is used for suppressing magnetizing inrush current and comprises an alternating current power supply V1, an equivalent direct current compensation voltage source Vc, a first bridge full-wave rectifier B1 and a direct current reactor L1, wherein a first input end of the first bridge full-wave rectifier B1 is connected with the alternating current power supply V1, a second input end of the first bridge full-wave rectifier B1 is connected with a primary side of a main transformer T2, and the equivalent direct current compensation voltage source Vc takes the alternating current power supply V1 as input and is connected in series with the direct current reactor L1 and then connected between a first output end and a second output end of the first bridge full-wave rectifier B1 in parallel.
The equivalent direct current compensation voltage source Vc is composed of an isolation transformer T1 and a second full-wave bridge rectifier B2, one end of a primary side of the isolation transformer T1 is connected with an alternating current power supply V1, the other end is grounded, a secondary side of the isolation transformer T1 is used as an input of a second full-wave bridge rectifier B2, a first output end of the second full-wave bridge rectifier B2 is connected with a first output end of a first full-wave bridge rectifier B1 through a direct current reactor L1, and a second output end of the second full-wave bridge rectifier B2 is connected with a second output end of the first full-wave bridge rectifier B1.
The first full-wave bridge rectifier B1 is composed of 4 diodes D1, D2, D3 and D4, and the second full-wave bridge rectifier B2 is composed of 4 diodes D5, D6, D7 and D8.
When the transformer is in a no-load input or in a system voltage recovery process after external fault removal, the iron core of the transformer gradually approaches a saturation state, the line current rapidly rises, diodes D1 and D4 in a first bridge type full-wave rectifier B1 are conducted, the line current flows through a direct current reactor L1, the exciting current is restrained, and the running state at the moment is a current-limiting state;
when the magnetizing inrush current is restrained, the direct current reactor L1 starts to release the energy stored in the current limiting state, the voltage of the direct current reactor is reversed, the diodes D1, D2, D3 and D4 are all conducted, the circuit of the restraining device conducts afterflow, the voltage of two ends of the circuit is close to 0 and is in a short circuit state, the main transformer T2 is directly connected with the alternating current power supply V1, and the running state is the afterflow state;
when the energy stored in the direct current reactor L1 is exhausted, the transformer is charged completely, the circuit enters a stable state, the diodes D1, D2, D3 and D4 are always kept on, the suppression device is in a short-circuit state, the main transformer T2 is directly connected with the alternating current power supply V1, and the end voltage and the current of a load are not influenced.
In a steady state, the equivalent dc compensation voltage source Vc is used to compensate the voltage drop caused by the forward conducting voltage of the first bridge full-wave rectifier B1 and the coil resistor R1 of the dc reactor L1, and the value of the transformation ratio N of the isolation transformer T1 depends on the magnitude of the voltage drop.
Compared with the prior art, the invention has the following advantages:
when the transformer is in no-load operation, the suppression device connects the direct current reactor L1 into a system through automatic conduction of the diode to suppress the generation of excitation inrush current, and when the transformer is in steady-state operation, the suppression device is regarded as short circuit and has no influence on the operation of the system.
And secondly, no extra control and detection circuit is required to be added during actual operation.
And thirdly, the direct current compensation voltage source can compensate voltage loss caused by forward conduction voltage of the bridge rectifier diode and coil resistance of the direct current reactor.
Fourthly, the structure is simple, and the reliability is high.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Fig. 2 is an equivalent schematic diagram of the present invention operating in a current limiting state.
Fig. 3 is an equivalent schematic diagram of the present invention operating in a freewheeling state.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in fig. 1, the present invention provides a voltage compensation type transformer magnetizing inrush current suppression device, which specifically comprises:
the device is connected in series between the primary side of a main transformer T2 and an alternating current power supply V1, and consists of a direct current reactor L1, a first bridge type full-wave rectifier B1, an isolation transformer T1 and a second bridge type full-wave rectifier B2, diodes D1, D2, D3 and D4 form a first bridge type full-wave rectifier B1, diodes D5, D6, D7 and D8 form a second bridge type full-wave rectifier B2, the isolation transformer T1 and the second bridge type full-wave rectifier B2 form an equivalent direct current compensation voltage source Vc to generate compensation voltage, and the direct current reactor L1 is connected in series with the equivalent direct current compensation voltage Vc and then connected in parallel with the first bridge type full-wave rectifier B1.
With reference to fig. 1, 2 and 3, the working principle of the present invention is:
when the switch K1 is switched on, the main transformer T2 is put into no-load operation, the transformer core gradually approaches a saturation state, the line current I rapidly rises, the pair of diodes D1 and D4 of the first bridge full-wave rectifier B1 is turned on, the diode D1, the dc reactor L1, the reactor coil resistor R1, the equivalent dc compensation voltage source Vc, and the diode D4 are sequentially connected in series, the line current flows through the dc reactor L1, the excitation current generated by the main transformer T2 is suppressed by the dc reactor L1, this operation state is referred to as a current-limiting state, and the equivalent circuit is shown in fig. 2.
When the magnetizing inrush current is suppressed, the direct current reactor L1 starts to release the energy stored in the current limiting state, at the same time, the diodes D1, D2, D3 and D4 are all conducted at the same time, the inrush current circuit is suppressed from freewheeling, the voltage at two ends of the suppression device is close to zero and can be regarded as a short circuit, the transformer is directly connected with a voltage source, the operation state is called a freewheeling state, and the equivalent circuit is shown in FIG. 3. At this stage, line current I flows through the transformer through the conducting diode, automatically bypassing dc reactor L1, dc reactor L1 discharges the stored energy, and the voltage reverses.
When the stored energy of the L1 is exhausted, the transformer is charged, the circuit enters a stable state, the direct-current compensation voltage source can compensate voltage drop caused by forward conduction voltage of the bridge rectifier diode and coil resistance of the direct-current reactor, the diodes D1-D4 are always kept in a conduction state, and an equivalent circuit diagram is the same as that in a follow current state. The suppression device is considered a short circuit at this stage and the main transformer T2 is connected directly to the power supply. The load side voltage and current waveforms are not affected by the suppression means at steady state.
In a stable state, the direct-current compensation voltage source Vc compensates voltage drop caused by forward conduction voltage of the bridge rectifier diode and coil resistance R1 of the direct-current reactor, and the value of the transformation ratio N of the isolation transformer depends on the amplitude of the voltage drop.
Claims (1)
1. A voltage compensation type transformer magnetizing inrush current suppression device is used for suppressing magnetizing inrush current and is characterized by comprising an alternating current power supply (V1), an equivalent direct current compensation voltage source (Vc), a first bridge full-wave rectifier (B1) and a direct current reactor (L1), wherein a first input end of the first bridge full-wave rectifier (B1) is connected with the alternating current power supply (V1), a second input end of the first bridge full-wave rectifier is connected with a primary side of a main transformer (T2), the equivalent direct current compensation voltage source (Vc) takes the alternating current power supply (V1) as an input, the equivalent direct current compensation voltage source (Vc) is connected in series with the direct current reactor (L1) and then connected between a first output end and a second output end of the first bridge full-wave rectifier (B1), the equivalent direct current compensation voltage source (Vc) is composed of an isolation transformer (T1) and a second full-wave bridge rectifier (B2), one end of the isolation transformer (T1) is connected with the alternating current power supply (V1), the other end of the second full-wave bridge rectifier is grounded, the secondary side of the second full-wave bridge rectifier is used as the input of a second full-wave bridge rectifier (B2), the first output end of the second full-wave bridge rectifier (B2) is connected with the first output end of a first bridge full-wave rectifier (B1) through a direct current reactor (L1), the second output end of the second full-wave bridge rectifier (B2) is connected with the second output end of a first bridge full-wave rectifier (B1), the first bridge full-wave rectifier (B1) is composed of 4 diodes (D1, D2, D3 and D4), and the second bridge full-wave rectifier (B2) is composed of 4 diodes (D5, D6, D7 and D8);
when the transformer is in a no-load input or in a system voltage recovery process after external fault removal, the iron core of the transformer gradually approaches a saturation state, the line current rapidly rises, diodes (D1 and D4) in a first bridge type full-wave rectifier (B1) are conducted, the line current flows through a direct current reactor (L1), the exciting current is restrained, and the running state at the moment is a current limiting state;
when the magnetizing inrush current is restrained, the direct current reactor (L1) starts to release energy stored in a current limiting state, the voltage of the direct current reactor is reversed, the diodes (D1, D2, D3 and D4) are all conducted, the circuit of the restraint device continues current, the voltage of two ends of the circuit of the restraint device is close to 0 and is in a short-circuit state, the main transformer (T2) is directly connected with the alternating current power supply (V1), and the running state at the moment is a current-continuing state;
when the stored energy of the direct current reactor (L1) is exhausted, the transformer is charged completely, the circuit enters a stable state, the diodes (D1, D2, D3 and D4) are always kept on, the suppression device is in a short-circuit state, the main transformer (T2) is directly connected with the alternating current power supply (V1), and the end voltage and the current of a load are not influenced;
in a steady state, the equivalent DC compensation voltage source (Vc) is used for compensating a voltage drop caused by a forward conducting voltage of the first bridge type full-wave rectifier (B1) and a coil resistor (R1) of the DC reactor (L1), and the value of a transformation ratio N of the isolation transformer (T1) depends on the magnitude of the voltage drop.
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| CN201910017408.2A CN109599837B (en) | 2019-01-08 | 2019-01-08 | Voltage compensation type transformer excitation inrush current suppression device |
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| CN112865068B (en) * | 2019-11-27 | 2023-02-28 | 中国船舶重工集团公司第七一九研究所 | Linear attenuation voltage compensation control method for dual-power switching device |
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| CN101034803B (en) * | 2007-01-23 | 2010-05-19 | 南京师范大学 | Failure current limit device based on the rectifying bridge and bidirectional switch switching |
| CN201918719U (en) * | 2011-01-18 | 2011-08-03 | 南京师范大学 | Exciting-surge-inhibiting circuit for three-phase transformers |
| CN201946971U (en) * | 2011-01-18 | 2011-08-24 | 南京师范大学 | Magnetizing inrush current suppression circuit in single-phase transformer |
| CN102412560A (en) * | 2011-12-27 | 2012-04-11 | 保定天威集团有限公司 | Single-phase-transformer-based inrush current research method and device |
| CN102882200B (en) * | 2012-10-31 | 2014-12-17 | 东南大学 | Bridge type fault current limiter with current balancing effect |
| CN104779596A (en) * | 2015-04-20 | 2015-07-15 | 国家电网公司 | Direct-current reactor type magnetizing inrush current suppressor |
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