CN110941303A - Voltage stabilizing transformer based on magnetically controlled reactor - Google Patents

Voltage stabilizing transformer based on magnetically controlled reactor Download PDF

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Publication number
CN110941303A
CN110941303A CN201911349034.0A CN201911349034A CN110941303A CN 110941303 A CN110941303 A CN 110941303A CN 201911349034 A CN201911349034 A CN 201911349034A CN 110941303 A CN110941303 A CN 110941303A
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transformer
voltage
magnetically controlled
winding
phase
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田庆阳
回嵩杉
王睿
王超
王琨
胡冰蕾
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Dandong De Yuan Electric Appliance Co Ltd
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Dandong De Yuan Electric Appliance Co Ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/40—Structural association with built-in electric component, e.g. fuse
    • H01F27/402—Association of measuring or protective means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/40—Structural association with built-in electric component, e.g. fuse
    • H01F2027/408—Association with diode or rectifier

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention discloses a voltage stabilizing transformer based on a magnetically controlled reactor, which comprises three parts, namely a magnetically controlled reactor, a transformer and an excitation unit, wherein one end of a working winding of the magnetically controlled reactor is connected with one end of a primary winding of the transformer to form a series connection structure, so that a body of the magnetically controlled voltage stabilizing transformer is formed; the other end of the working winding of the magnetic control reactor and the other end of the primary winding of the transformer are used as the voltage input end of the magnetic control voltage stabilizing transformer and are connected with a power supply; the secondary side of the transformer comprises two windings, one of the windings is a load driving winding, and the other winding provides excitation voltage and excitation current for the magnetically controlled reactor through an excitation unit EXC. The voltage drop of the magnetically controlled reactor is adjusted by adjusting the impedance of the magnetically controlled reactor, so that the input voltage of the transformer is stabilized, and the output voltage of the transformer is stabilized at a specified value; the invention can be used as a distribution transformer and a low-voltage alternating current voltage stabilizer.

Description

Voltage stabilizing transformer based on magnetically controlled reactor
Technical Field
The invention relates to a distribution transformer with a voltage stabilizing function, in particular to a voltage stabilizing transformer based on a magnetically controlled reactor.
Background
The power industry of China has been rapidly developed for more than 30 years, and particularly, the power supply capacity and the power supply quality are greatly improved through multiple urban and rural power grid transformation, so that the national development and the improvement of the life of people are promoted. However, because of wide territory and complex power supply environment in China, the phenomena of voltage drop and large voltage fluctuation still exist.
The existing distribution transformer is designed according to rated input voltage, the output voltage can reach the rated value under the rated input voltage, and when the input voltage is seriously lowered, the output voltage drop is obviously lower than the rated value.
In addition, the instant of large-scale load switching can also cause the instant fluctuation and change of voltage. Such voltage drops and frequent changes affect the quality of the power supply and also jeopardize the safety of the operation of the consumer.
Disclosure of Invention
Aiming at the defects of low voltage drop, poor stability, incapability of meeting the power supply quality requirement and the like of a low-voltage side of a distribution transformer in the prior art, the invention aims to solve the problem of providing a voltage stabilizing transformer based on a magnetically controlled reactor, which has the advantages of simple structure, large capacity, wide voltage stabilizing range and high response speed.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention relates to a voltage stabilizing transformer based on a magnetically controlled reactor, which comprises three parts, namely a magnetically controlled reactor, a transformer and an excitation unit, wherein one end of a working winding of the magnetically controlled reactor is connected with one end of a primary winding of the transformer to form a series connection structure, so that a body of the magnetically controlled voltage stabilizing transformer is formed; the other end of the working winding of the magnetic control reactor and the other end of the primary winding of the transformer are used as the voltage input end of the magnetic control voltage stabilizing transformer and are connected with a power supply; the secondary side of the transformer comprises two windings, one of the windings is a load driving winding, and the other winding provides excitation voltage and excitation current for the magnetically controlled reactor through an excitation unit EXC.
The excitation unit comprises an excitation module and a detection protection module, wherein the excitation module comprises a rectifying circuit, a filter capacitor, a central processing unit, a pulse width modulator and an IGBT chopper tube; two output ends of the secondary winding of the transformer are respectively connected with anodes of the first rectifier diode and the second rectifier diode, cathodes of the first rectifier diode and the second rectifier diode are connected in parallel to form a full-wave rectifier circuit, and a center tap of the first secondary winding of the transformer is used as a common end of the excitation circuit;
a filter capacitor is arranged between the cathode common end and the grounding end of the first rectifying diode and the second rectifying diode;
the output end of the three-terminal integrated voltage stabilizer is connected with the working power supply ends of the central processing unit and the pulse width modulator;
the IGBT chopper tube is used as a chopper element, the central processing unit and the pulse width modulator are used as controllers to form a direct current chopper circuit, the output end of the central processing unit is connected with the enabling end of the pulse width modulator, the output end of the pulse width modulator is connected with the grid electrode of the IGBT chopper tube, the emitter electrode of the IGBT chopper tube is connected with one end of the winding of the magnetic control reactor, and the other end of the winding is connected with the common end of the first secondary winding of the transformer.
The detection protection module comprises an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit comprises a current transformer and a central processing unit; the current transformer is arranged on the second secondary winding of the transformer, one output end of the current transformer is connected with the common end of the first winding of the transformer, and the other output end of the current transformer is connected with the current signal input end of the central processing unit; the overvoltage protection circuit comprises a voltage transformer and a central processing unit, wherein the high-voltage input end of the voltage transformer is directly connected in parallel with two ends of the input voltage of the magnetic control voltage stabilizing transformer, one end of the output end of the voltage transformer is connected with the common end of the first secondary winding of the transformer, and the other end of the output end of the voltage transformer is connected with the voltage signal input end of the central processing unit; the pulse width modulation signal output end of the central processing unit is connected with the control end of the pulse width modulator.
The invention has two modes of a single-phase structure and a three-phase structure, wherein the single-phase structure is formed by connecting a single-phase magnetically controlled reactor and a single-phase transformer in series, the three-phase magnetically controlled voltage stabilizing transformer is formed by connecting each phase of the three-phase magnetically controlled reactor and each phase of the three-phase transformer in series correspondingly, and the secondary side of each phase of the transformer provides excitation voltage and excitation current for the corresponding phase of the magnetically controlled reactor through the excitation unit of each phase.
The magnetically controlled reactor, the transformer and the excitation unit are in a common box type structure or a split type structure.
The invention has the following beneficial effects and advantages:
1. the invention relates to a voltage stabilizing transformer (magnetic control voltage stabilizing transformer for short) based on a magnetic control reactor, which utilizes the characteristic that the alternating current impedance of the magnetic control reactor is controllable, adjusts the voltage drop of the magnetic control reactor by adjusting the impedance of the magnetic control reactor, further stabilizes the input voltage of the transformer, and stabilizes the output voltage of the transformer on a specified value.
2. The invention relates to a voltage stabilizing transformer based on a magnetically controlled reactor, which is a distribution transformer with a voltage stabilizing function developed aiming at the power supply characteristics of 10kV and 35kV systems with low voltage or large fluctuation, solves the problem of low voltage or poor stability of a low-voltage side of a line, can also be used as a high-capacity low-voltage alternating current voltage stabilizer with 0.4kV/0.22kV input, and becomes a high-capacity direct current voltage stabilizer if an output end of the magnetically controlled voltage stabilizing transformer is provided with a rectifying and filtering device; when the magnetic control voltage stabilizing transformer is used as a 10kV or 35kV distribution transformer, the increase of the equipment cost is not large.
3. The excitation system adopts a working mode of direct-current chopping, an IGBT element is adopted as a chopping tube, the chopping frequency is increased from hundreds of hertz excited by a thyristor to thousands of hertz, and the dynamic response time of the magnetically controlled voltage stabilizing transformer is shortened from hundreds of milliseconds to within 30 milliseconds; and the voltage stabilization precision of the magnetic control voltage stabilization transformer is improved by adopting an advanced sampling technology and a rapid calculation method (realized by software running on a CPU).
4. Because the voltage stabilizing transformer is a combination of the magnetically controlled reactor and the distribution transformer, the voltage stabilizing transformer has the basic function of the distribution transformer and also has the function of stabilizing output voltage, is suitable for the application occasions where the voltage at the tail end of a line is seriously lowered and is also suitable for the occasions where the line voltage fluctuates frequently and the fluctuation range is large, and is a novel distribution transformer with good voltage stabilizing performance.
Drawings
FIG. 1 is a schematic diagram of a single-phase electrical structure of a voltage stabilizing transformer based on a magnetically controlled reactor according to the present invention;
FIG. 2 is a schematic diagram of a three-phase electrical structure of a voltage stabilizing transformer based on a magnetically controlled reactor according to the present invention;
FIG. 3 is an electrical schematic diagram of an excitation unit according to the present invention;
fig. 4 is an equivalent circuit of the single-phase magnetic control voltage stabilizing transformer of the invention.
Detailed Description
The invention is further elucidated with reference to the accompanying drawings.
As shown in FIG. 1, the voltage stabilizing transformer (abbreviated as magnetically controlled voltage stabilizing transformer) based on the magnetically controlled reactor of the invention comprises a magnetically controlled reactor L, a transformer T and an excitation unit EXC, wherein a working winding N of the magnetically controlled reactor L is providedLOne end of and a primary winding N of the transformer TTOne end of the magnetic control voltage stabilizing transformer is connected to form a series structure to form a body of the magnetic control voltage stabilizing transformer; l working winding N of magnetically controlled reactorLAnd the other end of the transformer T primary winding NTThe other end of the magnetic control voltage stabilizing transformer is used as a voltage input end of the magnetic control voltage stabilizing transformer and a power supply UiConnecting; the secondary side of the transformer T is a load driving side, and meanwhile, excitation voltage and excitation current are provided for the magnetically controlled reactor through the excitation unit EXC.
The equivalent circuit is shown in fig. 4.
As shown in fig. 3, the excitation unit EXC includes an excitation module and a detection protection module, wherein the excitation module includes a rectification circuit, a filter capacitor, a central processing unit CPU, a pulse width modulator PWM and an IGBT chopper V1(ii) a Transformer T secondary side first winding N1Two output terminals of the first and second rectifying diodes D are connected with the first and second rectifying diodes respectively1And D2Is connected with the anode of the first and second rectifying diodes D1And D2The cathodes of the transformers are connected in parallel to form a full-wave rectifying circuit, and a first winding N is arranged on the secondary side of the transformer T1The central tap of the transformer is used as a common end of the excitation circuit;
first and second rectifier diodes D1、D2A filter capacitor C is arranged between the cathode common terminal and the grounding terminal1；
First and second rectifier diodes D1、D2The cathode common terminal of the first and second resistors R1、R2The output end of the three-terminal integrated voltage stabilizer IC is connected with a central processing unit CPU and the power input end of a pulse width modulator PWM;
the output end of the CPU is connected with the enable end of the PWM, and the output end of the PWM is connected with the IGBT chopper tube V1Are connected with each other, IGBT chopper tube V1Emitter of (2) and N of magnetically controlled reactor LKOne end of the winding is connected with NKThe other end of the winding and a first winding N of a T secondary side of the transformer1Are connected.
The detection protection module comprises an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit comprises a current transformer CT and a central processing unit CPU, the current transformer CT is arranged on a secondary side second winding N of the transformer T0At one end of its output and the first winding N of the transformer T1The other end of the common end is connected with a current signal input end (end 1) of a central processing unit CPU; the overvoltage protection circuit comprises a voltage transformer PT and a central processing unit CPU, wherein the high-voltage input end of the voltage transformer PT is directly connected in parallel with the input voltage U of the magnetic control voltage-stabilizing transformeriTwo ends, one end of the PT output end of the voltage transformer and the first winding N of the secondary side of the transformer1The other end of the common end is connected with a voltage signal input end (2 end) of a Central Processing Unit (CPU); the output end of the pulse width modulation signal of the CPU is connected with the control end of the PWM.
The true bookIn the embodiment, the voltage stabilizing transformer based on the magnetically controlled reactor consists of a magnetically controlled reactor L, a transformer T and an excitation unit, wherein the magnetically controlled reactor L is used as a voltage adjusting element and a primary winding N of the transformerTThe (working windings) are connected in series. By adjusting working winding N of magnetic control reactor LLVoltage drop U acrossLPrimary winding N of holding transformer TTVoltage U acrossTStabilizing and further stabilizing the output voltage U of the transformer0. The exciting voltage and exciting current of the magnetically controlled reactor L are taken from the first winding N of the transformer T1The transformer T not only provides electric energy for the load, but also has the function of an exciting transformer. Therefore, the transformer T is a load driving element and also provides excitation voltage and current for the magnetically controlled reactor.
The body of the single-phase magnetically controlled voltage stabilizing transformer is formed by serially connecting a magnetically controlled reactor L and a transformer T. L working winding N of magnetically controlled reactorLOne end of and a primary winding N of the transformer TTOne end of the magnetic control voltage stabilizing transformer is connected to form a series structure to form a body of the magnetic control voltage stabilizing transformer. L working winding N of magnetically controlled reactorLAnd the other end of the transformer T primary winding NTThe other end of the magnetic control voltage stabilizing transformer is used as a voltage input end of the magnetic control voltage stabilizing transformer and a single-phase power supply UiAre connected.
The excitation unit of the single-phase magnetic control voltage-stabilizing transformer comprises an excitation module and a detection protection module, wherein the excitation module comprises a rectifying circuit, a filter capacitor, a Central Processing Unit (CPU), a Pulse Width Modulator (PWM) and an Insulated Gate Bipolar Translator (IGBT) chopper tube V1(ii) a The detection protection module comprises a current transformer CT, a voltage transformer PT, an overcurrent protection circuit and an overvoltage protection circuit.
First winding N of transformer T1Two output terminals of the first and second rectifying diodes D are connected with the first and second rectifying diodes respectively1、D2Is connected with the anode of the first and second rectifying diodes D1、D2The cathodes of the full-wave rectifying circuit are connected in parallel to form a full-wave rectifying circuit; first winding N of transformer T1The center tap of the transformer is a common end of the excitation circuit; filter capacitor C1Connected in parallel to the first and second rectifier diodes D1、D2Between the cathode and the common terminal ⊥, a first resistor R and a second resistor R1、R2A series voltage division circuit is formed and is used as a working power supply of a central processing unit CPU and a pulse width modulator PWM after being stabilized by a three-terminal integrated voltage stabilizer IC; the output end of the CPU is connected with the enable end of the PWM of the pulse width modulator to control the pulse width output by the PWM circuit; PWM output end of pulse width modulator and IGBT chopper tube V1Is an IGBT chopper tube V1Providing a driving control signal; IGBT chopper tube V1Emitter of (2) and N of magnetically controlled reactor LKOne end of the winding is connected to provide excitation voltage and excitation current for the magnetically controlled reactor L, NKThe other end of the winding is connected with the first winding N of the transformer T1Is connected with a common terminal ⊥ to form an excitation system of the magnetically controlled reactor L, and a third diode D3Is a freewheeling element.
The detection protection module of the magnetic control voltage stabilizing transformer mainly comprises an overcurrent protection circuit and an overvoltage protection circuit. Wherein the current transformer CT in the overcurrent protection circuit is arranged on the secondary side second winding N of the transformer T0On the winding, one end of the CT output end of the current transformer and the first winding N of the transformer T1Is connected with the common terminal ⊥, and the other end is connected with the current signal input end 1 of the CPU, the current transformer CT monitors the secondary side second winding N of the transformer T at any time0And transmits the monitoring data to the current signal input terminal 1 of the central processing unit CPU. When the current signal from the current transformer CT exceeds the set value of current protection, the central processing unit CPU narrows or disappears the driving pulse output by the PWM, so that the output current of the IGBT is reduced or disappears, the impedance of the magnetically controlled reactor L is changed, the output voltage of the transformer T is further changed, and the overcurrent protection is implemented on the magnetically controlled voltage stabilizing transformer.
The high-voltage input end of a voltage transformer PT in the overvoltage protection circuit is directly connected in parallel with the input voltage U of the magnetic control voltage-stabilizing transformeriTwo ends, one end of the PT output end of the voltage transformer and a first winding N of a secondary side of the transformer T1Is connected with the common terminal ⊥, and the other end is connected with the voltage signal input terminal 2 of the central processing unit CPU, and the voltage transformer PT constantly monitors the input voltage U of the magnetic control voltage stabilizing transformeriWidth of change ofAnd transmits the monitoring data to a voltage signal input end 2 of the central processing unit CPU. When the voltage signal from the voltage transformer PT exceeds the set value of voltage protection, the central processing unit CPU narrows or disappears the driving pulse output by the PWM, so that the output current of the IGBT is reduced or disappears, the impedance of the magnetic control reactor L is changed, the output voltage of the magnetic control voltage stabilizing transformer is further changed, and overvoltage protection is implemented on the electric equipment.
The invention has two modes of a single-phase structure and a three-phase structure, wherein the single-phase structure is formed by connecting a single-phase magnetically controlled reactor and a single-phase transformer in series, and the three-phase magnetically controlled voltage stabilizing transformer is formed by connecting each phase L of the three-phase magnetically controlled reactor with each phase L of the three-phase magnetically controlled voltage stabilizing transformerA/LB/LCAnd each phase T of three-phase transformerA/TB/TCAre correspondingly connected in series to form a transformer T with each phase secondary side N1a/N1b/N1cAnd providing excitation voltage and excitation current for corresponding phases of the magnetically controlled reactor through the excitation units EXC of the respective phases. As shown in fig. 2, the three-phase magnetic control voltage stabilizing transformer has the following specific connection structure:
1) connection relation of three-phase magnetic control voltage-stabilizing transformer body
The three-phase magnetic control voltage stabilizing transformer body consists of a three-phase magnetic control reactor and a three-phase transformer. 3 working windings of the three-phase magnetically controlled reactor are respectively connected with 3 primary windings of the corresponding three-phase transformer in series, namely an A-phase working winding N of the three-phase magnetically controlled reactorLAA-phase primary winding N of three-phase transformer TTAAre connected in series; b-phase working winding N of three-phase magnetically controlled reactorLBPrimary winding N phase with transformer BTBAre connected in series; c-phase working winding N of magnetically controlled reactorLCPrimary winding N of C phase of transformerTCAre connected in series. Winding NLAAnd NTA、NLBAnd NTB、NLCAnd NTCAfter being respectively connected in series, the three phases are sequentially connected end to form △ connection, and 3 vertexes connected △ are respectively connected with the phase A, the phase B and the phase C of the three-phase power transmission bus to be used as input voltage of the magnetic control voltage stabilizing transformer.
2) Connection relation of excitation system of three-phase magnetic control voltage-stabilizing transformer
Because each phase of the three-phase magnetic control voltage stabilizing transformer is formed by connecting a magnetic control reactor and a transformer in series, the three-phase magnetic control voltage stabilizing transformer is equivalent to the series combination of three single-phase magnetic control voltage stabilizing transformers, and the series combination of each phase has the same working mode, the three-phase magnetic control voltage stabilizing transformer has 3 sets of completely same excitation units. The excitation system of the three-phase magnetic control voltage stabilizing transformer consists of 3 completely identical independent systems, one phase of the excitation system is shown in figure 3, and the other two-phase excitation systems are identical to the phase.
First and second diodes D1、D2And the first winding N1Forming a full-wave rectifying circuit through a capacitor C1After filtering, the filtered signal is used as a direct current working power supply of the excitation unit EXC; first and second resistors R1、R2Dividing the full-wave rectified voltage, and then stabilizing the voltage by a three-terminal integrated voltage stabilizer IC to be used as a working power supply of a central processing unit CPU and a pulse width modulator PWM; to be detected by current transformers CT and potential transformers PT
The current signal and the voltage signal are respectively sent to a pin 1 and a pin 2 of a central processing unit CPU, the output pulse width of the PWM is controlled after the data processing of the central processing unit CPU, and then the IGBT chopper tube V is controlled1The output current controls the impedance and voltage drop of the magnetically controlled reactor L to stabilize the primary voltage U of the transformer TTThe function of (1).
In order to facilitate the connection of the excitation unit with the magnetic control voltage stabilizing transformer body, the output/input ends of each phase of the three-phase excitation system are given the same numbers ① - ⑦ (as shown in fig. 2), and N of the magnetic control voltage stabilizing transformer bodyKNumbers ①, ② are given to both ends of the winding, and the first winding N is provided with1The three ends of the first winding are sequentially provided with numbers ③, ④ and ⑤ from top to bottom, and the second winding N is provided with a first winding and a second winding0 Numbers ⑥ and ⑦ are given to the two ends, so when the three-phase excitation system is connected with the three-phase magnetic control voltage stabilizing transformer body, as long as each phase is connected with the same number, the connection error can not occur.
The working principle and analysis of the voltage stabilizing transformer based on the magnetically controlled reactor are as follows:
as shown in fig. 4, a magnetically controlled voltage-stabilizing transformer, etcThe effective circuit is used for explaining the working principle of the magnetic control voltage stabilizing transformer. In FIG. 4, RLThe equivalent resistance of the magnetically controlled reactor L is represented by a symbol of a variable resistor in order to express the controllable impedance characteristic of the magnetically controlled reactor; rTIs the equivalent resistance of the transformer T; u shapeiThe input voltage is the input voltage of the magnetic control voltage stabilizing transformer (namely 10kV or 35kV system voltage); u shapeRLIs a resistance RLI.e. the voltage drop of the magnetically controlled reactor L; u shapeRTIs a resistance RTThe voltage across it, i.e. the primary voltage of the transformer T.
As can be seen from FIG. 4, the resistance RLAnd RTForm a series voltage-dividing circuit, the primary voltage of the transformer T
Figure BDA0002334203310000061
Voltage drop U of magnetically controlled reactorRL＝iXL. Wherein i is a working winding N of a magnetic control reactor L flowing throughLCurrent of (2), XLIs the alternating current impedance of the magnetically controlled reactor. This formula shows that the voltage drop U of the magnetically controlled reactorRLUnder the condition of a certain current i, the voltage is completely limited by the alternating-current impedance X of the magnetically controlled reactorLChanging the impedance XLThe voltage drop U of the magnetically controlled reactor can be changedRL。
When the system voltage UiWhen the voltage rises, the impedance of the magnetically controlled reactor increases, and the voltage drop U is reducedRLIncrease voltage URLThe increased part is equal to the system voltage UiRaised part, thus primary winding N of transformer TTThe voltage at both ends is maintained constant, and the output voltage U is constant0And keeping stable.
When the system voltage UiWhen the voltage is reduced, the impedance of the magnetic control reactor is reduced, and the voltage drop U is reducedRLAlso reduced, voltage URLThe reduced portion is equal to the system voltage UiReduced portion, then primary winding N of transformer TTThe voltage at both ends is maintained constant, and the output voltage U is constant0And keeping stable.
Therefore, the voltage stabilizing process of the magnetically controlled voltage stabilizing transformer is a result of impedance change of the magnetically controlled reactor, and the magnetically controlled reactor converts the value of the system voltage change into voltage drop of the magnetically controlled reactor by changing the impedance value of the magnetically controlled reactor, so that the voltage at two ends of the primary winding of the transformer is kept unchanged.
From the above analysis, it can be seen that the magnetically controlled voltage stabilizing transformer can only transfer a part of the voltage higher than the designed value to the two ends of the magnetically controlled reactor, and keep the primary voltage of the transformer stable if the system voltage, i.e. the input voltage U of the magnetically controlled voltage stabilizing transformeriWhen the voltage is lower than the designed specified value, the magnetic control voltage stabilizing transformer can not play a role of stabilizing voltage. In order to solve the problem, when designing the magnetic control voltage stabilizing transformer, the lowest value of the system voltage is used as the input voltage U of the magnetic control voltage stabilizing transformeri. For example, the minimum voltage value of 10kV system is 10-10 × 7% ═ 9.3kV, and the minimum voltage value of 35kV system is 35-35 × 5% ═ 33.25 kV. Rated input voltage U of magnetic control voltage-stabilizing transformer of 10kV systemiThe minimum voltage drop of the 9.3 kV-magnetically controlled reactor,
rated input voltage of magnetic control voltage stabilizing transformer of 35kV system is Ui33.25 kV-minimum voltage drop of the magnetically controlled reactor. The "minimum voltage drop" here is determined by the design value of the magnetically controlled reactor.
The magnetic control voltage stabilizing transformer can automatically stabilize output voltage, and is derived from the structural design of the magnetic control voltage stabilizing transformer. The magnetically controlled voltage-stabilizing transformer is formed by combining a magnetically controlled reactor and a transformer in series, and the impedance of the magnetically controlled reactor is adjustable, so that the voltage drop of the magnetically controlled reactor is adjustable, and when the system voltage (namely the input voltage U of the magnetically controlled voltage-stabilizing transformer) is equal to the system voltagei) When the voltage is increased or decreased, the impedance of the magnetically controlled reactor is changed immediately, and the end voltage U of the magnetically controlled reactor is changedLAnd then the voltage is changed, and the variable quantity of the system voltage is transferred to two ends of the magnetically controlled reactor, thereby maintaining the primary side voltage U of the transformerTThe voltage is kept unchanged, so that the input/output voltage of the transformer is stabilized, and the purpose of stabilizing the output voltage is achieved. The combination enables the power transformer to have a voltage stabilizing function, improves the power transmission quality of the transformer and improves the stability of power supply.
The impedance adjusting range and the voltage stabilizing capacity of the magnetically controlled voltage stabilizing transformer are determined by the impedance adjusting characteristic of the magnetically controlled reactor. The impedance of the magnetically controlled reactor can be changed along with the change of the exciting current, and no mechanical factor exists in the impedance adjusting process, so that the impedance of the magnetically controlled reactor can be continuously and quickly and smoothly adjusted, the transition time from the minimum impedance to the maximum impedance or from the maximum impedance to the minimum impedance is not more than 30ms, the excellent adjusting performance of the magnetically controlled voltage stabilizing transformer is shown, and a voltage stabilizing device capable of quickly stabilizing voltage is provided for a power supply line with frequent voltage fluctuation.
The national grid regulation indicates that the voltage fluctuation range of a 10kV system is +/-7 percent, namely 9.3 kV-10.7 kV; the voltage fluctuation range of the 35kV system is +/-5 percent, namely 33.25 kV-36.75 kV; the voltage fluctuation range of the 0.4kV low-voltage system is +/-10, namely 0.36 kV-0.44 kV.
The working voltage of the magnetic control voltage stabilizing transformer is larger than the voltage fluctuation range allowed by the state. For a single-phase low-voltage magnetic control voltage stabilizing transformer, the output voltage can be stabilized at a rated value within the range of 220V +/-20%, namely 176-264V; for a three-phase low-voltage magnetic control voltage stabilizing transformer, the output voltage can be stabilized at a rated value within the range of 380V +/-20%, namely within the range of 304-456V; for a 10kV three-phase magnetic control voltage stabilizing transformer, the output voltage can be stabilized at a rated value within the range of 10kV +/-10%, namely within the range of 9-11 kV; for a 35kV three-phase magnetic control voltage stabilizing transformer, the output voltage can be stabilized at a rated value within the range of 35kV +/-7%, namely within the range of 32.5-37.5 kV.
Working winding N of magnetically controlled reactorLPrimary winding N of the sum transformerTThe two reactance elements are connected in series, namely two reactance elements are connected in series and are in overcurrent protection mutually, and overvoltage and overcurrent impact cannot occur to the transformed input voltage, so that the reliability of the magnetic control voltage stabilizing transformer is improved.
Because of the terminal voltage U of the magnetically controlled reactor LLIs the system voltage UiMaximum value of and rated input voltage U of transformer TTThe difference of (a) is small compared to the system voltage, in comparison with the transformer TWhen the same current flows through the primary winding, the ratio of the capacity of the magnetically controlled reactor L corresponding to each level of voltage from 35kV to 0.22kV to the capacity of the transformer T is respectively as follows:
1) for a 35kV system magnetically controlled voltage stabilizing transformer, the ratio of the capacity of a magnetically controlled reactor L to the capacity of a transformer T is (37.5-32.5), i/32.5i is 0.15, and the ratio is 15%;
2) for a 10kV system magnetically controlled voltage stabilizing transformer, the ratio of the capacity of a magnetically controlled reactor L to the capacity of a transformer T is (11-9), i/9i is 0.22, and the ratio is 22%;
3) for the magnetron voltage stabilizing transformer of a 0.4kV system, the ratio of the capacity of the magnetron reactor L to the capacity of the transformer T is (456-304), i/304i is 0.16i/0.32i is 0.5, and the ratio is 50%;
4) for the magnetron voltage stabilizing transformer of a 0.22kV system, the ratio of the capacity of the magnetron reactor L to the capacity of the transformer T is (264-176), i/176i is 0.5, and the ratio is 50%.
Therefore, in the magnetically controlled voltage stabilizing transformer, the capacity of the magnetically controlled reactor is far smaller than that of the transformer. When the magnetic control voltage stabilizing transformer is used as a 10kV or 35kV distribution transformer, the increase of the equipment cost is not large.
In the invention, an excitation system of the magnetic control voltage-stabilizing transformer adopts a direct current chopping working mode, an IGBT element is adopted as a chopping tube, the chopping frequency is increased from hundreds of hertz excited by a thyristor to thousands of hertz, and the dynamic response time of the magnetic control voltage-stabilizing transformer is shortened from hundreds of milliseconds to within 30 milliseconds; and the voltage stabilizing precision of the magnetic control voltage stabilizing transformer is improved by adopting an advanced sampling technology and a rapid calculation method.

Claims (5)

1. The utility model provides a steady voltage transformer based on magnetically controlled reactor which characterized in that: the magnetic control voltage stabilizing transformer comprises three parts, namely a magnetic control reactor, a transformer and an excitation unit, wherein one end of a working winding of the magnetic control reactor is connected with one end of a primary winding of the transformer to form a series structure, so that a body of the magnetic control voltage stabilizing transformer is formed; the other end of the working winding of the magnetic control reactor and the other end of the primary winding of the transformer are used as the voltage input end of the magnetic control voltage stabilizing transformer and are connected with a power supply; the secondary side of the transformer comprises two windings, one of the windings is a load driving winding, and the other winding provides excitation voltage and excitation current for the magnetically controlled reactor through an excitation unit EXC.
2. The magnetically controlled reactor-based voltage stabilizing transformer of claim 1, characterized in that: the excitation unit comprises an excitation module and a detection protection module, wherein the excitation module comprises a rectifying circuit, a filter capacitor, a central processing unit, a pulse width modulator and an IGBT chopper tube; two output ends of the secondary winding of the transformer are respectively connected with anodes of the first rectifier diode and the second rectifier diode, cathodes of the first rectifier diode and the second rectifier diode are connected in parallel to form a full-wave rectifier circuit, and a center tap of the first secondary winding of the transformer is used as a common end of the excitation circuit; a filter capacitor is arranged between the cathode common end and the grounding end of the first rectifying diode and the second rectifying diode; the output end of the three-terminal integrated voltage stabilizer is connected with the working power supply ends of the central processing unit and the pulse width modulator; the IGBT chopper tube is used as a chopper element, the central processing unit and the pulse width modulator are used as controllers to form a direct current chopper circuit, the output end of the central processing unit is connected with the enabling end of the pulse width modulator, the output end of the pulse width modulator is connected with the grid electrode of the IGBT chopper tube, the emitter electrode of the IGBT chopper tube is connected with one end of the winding of the magnetic control reactor, and the other end of the winding is connected with the common end of the first secondary winding of the transformer.
3. The magnetically controlled reactor-based voltage stabilizing transformer of claim 2, characterized in that: the detection protection module comprises an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit comprises a current transformer and a central processing unit, the current transformer is arranged on a second secondary winding of the transformer, one output end of the current transformer is connected with the common end of a first winding of the transformer, and the other output end of the current transformer is connected with the current signal input end of the central processing unit; the overvoltage protection circuit comprises a voltage transformer and a central processing unit, wherein the high-voltage input end of the voltage transformer is directly connected in parallel with two ends of the input voltage of the magnetic control voltage stabilizing transformer, one end of the output end of the voltage transformer is connected with the common end of the first secondary winding of the transformer, and the other end of the output end of the voltage transformer is connected with the voltage signal input end of the central processing unit; the pulse width modulation signal output end of the central processing unit is connected with the control end of the pulse width modulator.
4. The magnetically controlled reactor-based voltage stabilizing transformer of claim 2, characterized in that: the single-phase structure is formed by connecting a single-phase magnetically controlled reactor and a single-phase transformer in series, the three-phase magnetically controlled voltage stabilizing transformer is formed by connecting each phase of the three-phase magnetically controlled reactor and each phase of the three-phase transformer in series correspondingly, and the secondary side of each phase of the transformer provides excitation voltage and excitation current for the corresponding phase of the magnetically controlled reactor through the excitation unit of each phase.
5. The magnetically controlled reactor-based voltage stabilizing transformer of claim 2, characterized in that: the magnetically controlled reactor, the transformer and the excitation unit are in a common box type structure or a split type structure.
CN201911349034.0A 2019-12-24 2019-12-24 Voltage stabilizing transformer based on magnetically controlled reactor Pending CN110941303A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112419822A (en) * 2020-11-16 2021-02-26 贵州电网有限责任公司 10KV distribution network equivalent test low-voltage simulation system and simulation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112419822A (en) * 2020-11-16 2021-02-26 贵州电网有限责任公司 10KV distribution network equivalent test low-voltage simulation system and simulation method thereof

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