A voltage stabilizing transformer based on magnetically controlled reactor

Abstract

The present invention discloses a voltage-stabilizing transformer based on a magnetically controlled reactor, comprising a magnetically controlled reactor, a transformer and an excitation unit, wherein one end of the working winding of the magnetically controlled reactor is connected to one end of the primary winding of the transformer to form a series structure, forming the body of the magnetically controlled voltage-stabilizing transformer; the other end of the working winding of the magnetically controlled reactor and the other end of the primary winding of the transformer are connected to the power supply as the voltage input end of the magnetically controlled voltage-stabilizing transformer; the secondary side of the transformer includes two windings, one is a load driving winding, and the other provides an excitation voltage and an excitation current for the magnetically controlled reactor through an excitation unit EXC. The present invention adjusts the voltage drop of the magnetically controlled reactor by adjusting its impedance, thereby stabilizing the input voltage of the transformer and stabilizing its output voltage at a specified value; the present invention can be used as a distribution transformer and can also be used as a low-voltage AC voltage stabilizer.

Description

Technical Field

[0001] 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 Art

[0002] Over the past 30 years, my country's power industry has developed rapidly, especially after multiple urban and rural power grid transformations, power supply capacity and quality have been greatly improved, promoting national development and improving people's lives. However, due to my country's vast territory and complex power supply environment, voltage sag and voltage fluctuations still exist.

[0003] The existing distribution transformers are designed according to the rated input voltage. The output voltage can reach the rated value only under the rated input voltage. When the input voltage drops seriously, the output voltage drops significantly below the rated value.

[0004] In addition, when a large load is switched on and off, the voltage will also fluctuate instantly. This voltage drop and frequent changes will affect the power supply quality and endanger the safe operation of electrical equipment. Summary of the invention

[0005] In view of the shortcomings of the prior art such as low voltage drop on the low-voltage side of the distribution transformer, poor stability, and inability to meet power supply quality requirements in a complex power supply environment, the problem to be solved by the present invention is to provide a voltage stabilizing transformer based on a magnetically controlled inductor with a simple structure, large capacity, wide voltage stabilization range, and fast response speed.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] The present invention discloses a voltage-stabilizing transformer based on a magnetically controlled inductor, comprising three parts: a magnetically controlled inductor, a transformer and an excitation unit, wherein one end of a working winding of the magnetically controlled inductor is connected with one end of a primary winding of the transformer to form a series structure, constituting the body of the magnetically controlled voltage-stabilizing transformer; the other end of the working winding of the magnetically controlled inductor and the other end of the primary winding of the transformer are connected with a power supply as voltage input ends of the magnetically controlled voltage-stabilizing transformer; the secondary side of the transformer comprises two windings, one is a load driving winding, and the other provides an excitation voltage and an excitation current for the magnetically controlled inductor through an excitation unit EXC.

[0008] The excitation unit includes an excitation module and a detection and protection module, wherein the excitation module includes a rectifier circuit, a filter capacitor, a central processing unit, a pulse width modulator and an IGBT chopper tube; the two output ends of the secondary winding of the transformer are respectively connected to the anodes of the first and second rectifier diodes, and the cathodes of the first and second rectifier diodes are connected in parallel to form a full-wave rectifier circuit, and the center tap of the first secondary winding of the transformer is used as the common end of the excitation circuit;

[0009] A filter capacitor is provided between the cathode common terminal of the first and second rectifier diodes and the ground terminal;

[0010] The cathode common end of the first and second rectifier diodes is connected to a three-terminal integrated voltage regulator after voltage division by resistors, and the output end of the three-terminal integrated voltage regulator is connected to the working power supply end of the central processing unit and the pulse width modulator;

[0011] A DC chopper circuit is formed by using an IGBT chopper tube as a chopper element, a central processing unit and a pulse width modulator as controllers, the output end of the central processing unit is connected to the enable end of the pulse width modulator, the output end of the pulse width modulator is connected to the gate of the IGBT chopper tube, the emitter of the IGBT chopper tube is connected to one end of the winding of the magnetically controlled inductor, and the other end of the winding is connected to the common end of the first secondary winding of the transformer.

[0012] The detection and protection module includes an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit includes a current transformer and a central processing unit; the current transformer is arranged on the second secondary winding of the transformer, one end of its output is connected to the common end of the first winding of the transformer, and the other end is connected to the current signal input end of the central processing unit; the overvoltage protection circuit includes a voltage transformer and a central processing unit, the high-voltage input end of the voltage transformer is directly connected in parallel to the input voltage ends of the magnetically controlled voltage-stabilizing transformer, one end of the voltage transformer output end is connected to the common end of the first secondary winding of the transformer, and the other end is connected to the voltage signal input end of the central processing unit; the pulse width modulation signal output end of the central processing unit is connected to the control end of the pulse width modulator.

[0013] The present invention has two structures: a single-phase structure and a three-phase structure. The single-phase structure is composed of a single-phase magnetically controlled inductor and a single-phase transformer connected in series. The three-phase magnetically controlled voltage-stabilizing transformer is composed of each phase of a three-phase magnetically controlled inductor and each phase of a three-phase transformer connected in series. The secondary sides of each phase of the transformer provide excitation voltage and excitation current for the corresponding phase of the magnetically controlled inductor through the excitation unit of each phase.

[0014] The magnetically controlled reactor, transformer and excitation unit are of a common box type or a split type structure.

[0015] The present invention has the following beneficial effects and advantages:

[0016] 1. The voltage-stabilizing transformer based on the magnetically controlled inductor (hereinafter referred to as the magnetically controlled voltage-stabilizing transformer) of the present invention utilizes the controllable AC impedance of the magnetically controlled inductor to adjust its voltage drop by adjusting the impedance of the magnetically controlled inductor, thereby stabilizing the input voltage of the transformer and stabilizing its output voltage at a specified value. The present invention can be used as a distribution transformer or as a low-voltage AC voltage stabilizer. Compared with ordinary voltage-stabilizing transformers, it has the characteristics of simple structure, large capacity, wide voltage stabilization range, good adjustment characteristics, fast response speed, etc.

[0017] 2. The voltage-stabilizing transformer based on the magnetically controlled inductor of the present invention is a distribution transformer with a voltage-stabilizing function developed for the power supply characteristics of 10kV and 35kV systems with low voltage or large fluctuations, so as to solve the problem of low voltage or poor stability on the low-voltage side of the line. It can also be used as a large-capacity low-voltage AC voltage stabilizer with 0.4kV / 0.22kV input. If a rectifier and filter device is provided at the output end of the magnetically controlled voltage-stabilizing transformer, it becomes a large-capacity DC voltage stabilizer. When the magnetically controlled voltage-stabilizing transformer is used as a 10kV or 35kV distribution transformer, the increase in its equipment cost is not large.

[0018] 3. The excitation system of the present invention adopts a DC chopping working mode and uses IGBT elements as chopper tubes. The chopping frequency is increased from hundreds of hertz of thyristor excitation to several thousand hertz, and the dynamic response time of the magnetically controlled voltage-stabilizing transformer is reduced from hundreds of milliseconds to less than 30 milliseconds. In addition, by adopting advanced sampling technology and fast calculation methods (implemented by software running on the CPU), the voltage stabilization accuracy of the magnetically controlled voltage-stabilizing transformer is improved.

[0019] 4. Since the voltage stabilizing transformer is a combination of a magnetically controlled reactor and a distribution transformer, in addition to the basic functions of a distribution transformer, it also has the function of stabilizing the output voltage. This voltage stabilizing transformer is suitable for applications where the voltage at the end of the line is severely low, and is also suitable for applications where the line voltage fluctuates frequently and with large fluctuations. It is a new type of distribution transformer with good voltage stabilization performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the single-phase electrical structure of a voltage stabilizing transformer based on a magnetically controlled reactor according to the present invention;

[0021] Figure 2 A schematic diagram of the three-phase electrical structure of a voltage-stabilizing transformer based on a magnetically controlled reactor according to the present invention;

[0022] Figure 3 It is a schematic diagram of the electrical structure of the excitation unit in the present invention;

[0023] Figure 4 It is the equivalent circuit of the single-phase magnetically controlled voltage-stabilizing transformer of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] like Figure 1 As shown, the present invention is a voltage-stabilizing transformer based on a magnetically controlled inductor (hereinafter referred to as a magnetically controlled voltage-stabilizing transformer), comprising a magnetically controlled inductor L, a transformer T and an excitation unit EXC, wherein the working winding N of the magnetically controlled inductor L L One end of the transformer T primary winding N TOne end of the magnetically controlled reactor L is connected to form a series structure, which constitutes the main body of the magnetically controlled voltage-stabilizing transformer; the working winding N of the magnetically controlled reactor L L The other end is connected to the primary winding N of the transformer T T The other end is used as the voltage input end of the magnetic control voltage stabilizing transformer and connected to the power supply U i The secondary side of the transformer T is the load driving side, and the excitation voltage and excitation current are provided to the magnetically controlled reactor through the excitation unit EXC.

[0026] Its equivalent circuit is Figure 4 shown.

[0027] like Figure 3 As shown, the excitation unit EXC includes an excitation module and a detection and protection module, wherein the excitation module includes a rectifier circuit, a filter capacitor, a central processing unit CPU, a pulse width modulator PWM and an IGBT chopper tube V 1 ; Transformer T secondary first winding N 1 The two output ends are connected to the first and second rectifier diodes D 1 With D 2 The anode of the first and second rectifier diodes D 1 With D 2 The cathode phase is connected in parallel to form a full-wave rectifier circuit. The first winding N of the secondary side of the transformer T 1 The center tap is used as the common end of the excitation circuit;

[0028] First, second rectifier diode D 1 , D 2 A filter capacitor C is provided between the cathode common terminal and the ground terminal. 1 ;

[0029] First, second rectifier diode D 1 , D 2 The cathode common terminal is connected through the first and second resistors R 1 , R 2 After voltage division, it is connected to a three-terminal integrated voltage regulator IC, and the output end of the three-terminal integrated voltage regulator IC is connected to the power input end of the central processing unit CPU and the pulse width modulator PWM;

[0030] The output end of the central processing unit CPU is connected to the enable end of the pulse width modulator PWM, and the output end of the pulse width modulator PWM is connected to the IGBT chopper tube V 1 The gate of the IGBT chopper tube V 1 The emitter of the magnetron reactor L is connected to the N K One end of the winding is connected, N K The other end of the winding is connected to the first winding N of the secondary side of the transformer T 1 The common end is connected to the

[0031] The detection protection module includes an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit includes a current transformer CT and a central processing unit CPU. The current transformer CT is arranged on the secondary side second winding N of the transformer T. 0 One end of its output is connected to the first winding N of the transformer T. 1 The overvoltage protection circuit includes a voltage transformer PT and a central processing unit CPU. The high-voltage input end of the voltage transformer PT is directly connected in parallel to the input voltage U of the magnetically controlled voltage stabilizing transformer. i Two ends, one end of the output end of the voltage transformer PT and the first winding N of the secondary side of the transformer 1 The common end is connected to the common end, and the other end is connected to the voltage signal input end (end 2) of the central processing unit CPU; the pulse width modulation signal output end of the central processing unit CPU is connected to the control end of the pulse width modulator PWM.

[0032] In this embodiment, the voltage-stabilizing transformer based on the magnetically controlled inductor is composed of three parts: the magnetically controlled inductor L, the transformer T and the excitation unit. The magnetically controlled inductor L is used as a voltage adjustment element and connected to the primary winding N of the transformer. T (Working winding) in series. By adjusting the magnetically controlled reactor L working winding N L The voltage drop across the terminals is U L Maintain the primary winding N of transformer T T The voltage across the two ends is U T Stable, thus stabilizing the transformer output voltage U 0 The excitation voltage and excitation current of the magnetically controlled reactor L are taken from the first winding N of the transformer T. 1 , so that the transformer T not only provides electrical energy for the load, but also has the function of an excitation transformer. Therefore, the transformer T is a load driving element and also provides excitation voltage and current for the magnetically controlled reactor.

[0033] The main body of the single-phase magnetically controlled voltage-stabilizing transformer is composed of a magnetically controlled reactor L and a transformer T in series. L One end of the transformer T primary winding N T One end of the magnetically controlled reactor L is connected to form a series structure, which constitutes the main body of the magnetically controlled voltage-stabilized transformer. L The other end is connected to the primary winding N of the transformer T T The other end is used as the voltage input end of the magnetically controlled voltage stabilizing transformer and connected to the single-phase power supply U i connected.

[0034] The excitation unit of the single-phase magnetically controlled voltage-stabilized transformer includes an excitation module and a detection and protection module. The excitation module includes a rectifier circuit, a filter capacitor, a central processing unit CPU, a pulse width modulator PWM, and an IGBT chopper tube V 1The detection and protection module includes a current transformer CT, a voltage transformer PT, and an overcurrent protection circuit and an overvoltage protection circuit.

[0035] Transformer T first winding N 1 The two output ends are connected to the first and second rectifier diodes D 1 , D 2 The anode of the first and second rectifier diodes D 1 , D 2 The cathode phase is connected in parallel to form a full-wave rectifier circuit; the first winding N of the transformer T 1 The center tap is the common end of the excitation circuit; the filter capacitor C 1 Connect the first and second rectifier diodes D in parallel 1 , D 2 Between the cathode and the common terminal ⊥; the first and second resistors R 1 , R 2 The series voltage divider circuit is formed, and after being stabilized by the three-terminal integrated voltage regulator IC, it is used as the working power supply of the central processing unit CPU and the pulse width modulator PWM; the output end of the central processing unit CPU is connected to the enable end of the pulse width modulator PWM to control the pulse width output by the PWM circuit; the output end of the pulse width modulator PWM is connected to the IGBT chopper tube V 1 The gate of the IGBT chopper tube is connected to 1 Provide drive control signal; IGBT chopper tube V 1 The emitter of the magnetron reactor L is connected to the N K One end of the winding is connected to provide excitation voltage and excitation current for the magnetically controlled reactor L, N K The other end of the winding is connected to the first winding N of the transformer T. 1 The common end ⊥ of the third diode D is connected to form the excitation system of the magnetically controlled reactor L. 3 It is the freewheeling element.

[0036] The detection and protection module of the magnetically controlled voltage-stabilized transformer is mainly composed of two parts: the overcurrent protection circuit and the overvoltage protection circuit. The current transformer CT in the overcurrent protection circuit is set on the second winding N of the secondary side of the transformer T. 0 On the winding, one end of the output terminal of the current transformer CT is connected to the first winding N of the transformer T 1 The other end is connected to the current signal input terminal 1 of the central processing unit CPU. The current transformer CT always monitors the secondary winding N of the transformer T. 0The output current of the IGBT is measured and the monitoring data is transmitted 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 the current protection, the central processing unit CPU narrows or eliminates the driving pulse output by the pulse width modulator PWM, reduces or eliminates the output current of the IGBT, changes the impedance of the magnetically controlled reactor L, and then changes the output voltage of the transformer T, thus implementing overcurrent protection for the magnetically controlled voltage-stabilizing transformer.

[0037] The high voltage input terminal of the voltage transformer PT in the overvoltage protection circuit is directly connected in parallel with the input voltage U of the magnetically controlled voltage stabilizing transformer. i Two ends, one end of the output end of the voltage transformer PT and the first winding N of the secondary side of the transformer T 1 The common terminal ⊥ of the voltage transformer is connected to the voltage signal input terminal 2 of the central processing unit CPU. The voltage transformer PT always monitors the input voltage U of the magnetically controlled voltage stabilizing transformer. i The monitoring data is transmitted to the voltage signal input terminal 2 of the central processing unit CPU. When the voltage signal from the voltage transformer PT exceeds the set value of the voltage protection, the central processing unit CPU narrows or eliminates the drive pulse output by the pulse width modulator PWM, reduces or eliminates the IGBT output current, changes the impedance of the magnetically controlled reactor L, and then changes the output voltage of the magnetically controlled voltage-stabilizing transformer, thus implementing overvoltage protection for the electrical equipment.

[0038] The present invention has two modes: single-phase structure and three-phase structure. The single-phase structure is composed of a single-phase magnetically controlled reactor and a single-phase transformer in series, and the three-phase magnetically controlled voltage-stabilizing transformer is composed of a three-phase magnetically controlled reactor and a single-phase transformer in series. A / L B / L C And each phase T of the three-phase transformer A / T B / T C The corresponding series is composed of the secondary side N of each phase of the transformer T 1a / N 1b / N 1c The excitation unit EXC of each phase provides the excitation voltage and excitation current for the corresponding phase of the magnetically controlled reactor. Figure 2 As shown, the specific connection structure is as follows:

[0039] 1) Connection relationship of the three-phase magnetic control voltage stabilizing transformer body

[0040] The three-phase magnetically controlled voltage-stabilizing transformer consists of a three-phase magnetically controlled reactor and a three-phase transformer. The three working windings of the three-phase magnetically controlled reactor are connected in series with the three primary windings of the corresponding three-phase transformer, that is, the A-phase working winding N of the three-phase magnetically controlled reactor is connected in series with the N-phase working winding N of the three-phase magnetically controlled reactor. LA The A-phase primary winding N of the three-phase transformer T TAPhase series connection; three-phase magnetically controlled reactor B phase working winding N LB With the transformer B phase primary winding N TB Phase series connection; magnetically controlled reactor C phase working winding N LC With the transformer C phase primary winding N TC Phase series. Winding N LA With N TA 、N LB With N TB 、N LC With N TC After being connected in series, they are connected end to end in a delta connection, and the three vertices of the delta connection are respectively connected to the A phase, B phase and C phase of the three-phase transmission bus as the input voltage of the magnetically controlled voltage stabilizing transformer.

[0041] 2) Connection relationship of the excitation system of the three-phase magnetically controlled voltage-stabilized transformer

[0042] Since each phase of the three-phase magnetically controlled voltage-stabilized transformer is composed of a magnetically controlled reactor and a transformer in series, which is equivalent to a series combination of three single-phase magnetically controlled voltage-stabilized transformers, and each phase series combination has the same working mode, the three-phase magnetically controlled voltage-stabilized transformer has three identical excitation units. The excitation system of the three-phase magnetically controlled voltage-stabilized transformer consists of three identical independent systems. Figure 3 The excitation system of one phase is shown, and the excitation systems of the other two phases are the same as that of this phase.

[0043] The first and second diodes D 1 , D 2 With the first winding N 1 A full-wave rectifier circuit is formed, and the capacitor C 1 After filtering, it is used as the DC working power supply of the excitation unit EXC; the first and second resistors R 1 , R 2 The full-wave rectified voltage is divided and then stabilized by a three-terminal integrated voltage regulator IC as the working power supply for the central processing unit CPU and the pulse width modulator PWM; the current transformer CT and the voltage transformer PT detect

[0044] The current signal and voltage signal are sent to the "1" and "2" pins of the central processing unit CPU respectively. After the data processing by the central processing unit CPU, the output pulse width of the pulse width modulator PWM is controlled, and then the IGBT chopper tube V is controlled. 1 The output current controls the impedance and voltage drop of the magnetically controlled reactor L, which stabilizes the primary voltage U of the transformer T. T role.

[0045] In order to facilitate the connection between the excitation unit and the magnetically controlled voltage-stabilized transformer body, the same number ① to ⑦ is given to the output / input end of each phase of the three-phase excitation system (such as Figure 2As shown), and in the N K The two ends of the winding are numbered ① and ②. 1 The three ends of the second winding N are numbered ③, ④, and ⑤ from top to bottom. 0 The two ends are numbered ⑥ and ⑦. In this way, when the three-phase excitation system is connected to the three-phase magnetic control voltage-stabilizing transformer body, as long as each phase is connected with the same number, there will be no connection error.

[0046] The working principle and analysis of the voltage stabilizing transformer based on the magnetically controlled reactor of the present invention are as follows:

[0047] like Figure 4 As shown in FIG. 1 , it is an equivalent circuit of a magnetically controlled voltage-stabilizing transformer, and the equivalent circuit is used to illustrate the working principle of the magnetically controlled voltage-stabilizing transformer. Figure 4 In, R L is the equivalent resistance of the magnetically controlled reactor L. In order to express the controllable impedance characteristic of the magnetically controlled reactor, the symbol of the variable resistor is used here to represent it; R T is the equivalent resistance of transformer T; U i is the input voltage of the magnetically controlled voltage-stabilizing transformer (i.e., 10kV or 35kV system voltage); U RL is the resistance R L The voltage drop of the magnetically controlled reactor L; U RT is the resistance R T The voltage across the two ends is the primary voltage of the transformer T.

[0048] Depend on Figure 4 It can be seen that the resistance R L With R T A series voltage divider circuit is formed, and the primary voltage of transformer T Voltage drop U of magnetically controlled reactor RL =iX L Where i is the current flowing through the working winding N of the magnetically controlled reactor L L The current, X L is the AC impedance of the magnetically controlled reactor. This formula shows that the voltage drop U RL Under the condition of constant current i, the voltage is completely subject to the AC impedance X of the magnetically controlled reactor. L , change the impedance X L The voltage drop U of the magnetically controlled reactor can be changed RL .

[0049] When the system voltage U i When it increases, the impedance of the magnetically controlled reactor increases, and the voltage drop U RL Increase, voltage U RL The increased part is equal to the system voltage U i The increased part, so the primary winding N of the transformer TT The voltage at both ends remains unchanged, and its output voltage U 0 Stay steady.

[0050] When the system voltage U i When it decreases, the impedance of the magnetically controlled reactor decreases, and the voltage drop U RL Also decreases, the voltage U RL The reduced part is equal to the system voltage U i The reduced part, so the primary winding N of the transformer T T The voltage at both ends remains unchanged, and its output voltage U 0 Stay steady.

[0051] It can be seen that the voltage stabilization process of the magnetically controlled voltage-stabilized transformer is the result of the impedance change of the magnetically controlled reactor. The magnetically controlled reactor converts the value of the system voltage change into its own voltage drop by changing its impedance value, thereby keeping the voltage across the primary winding of the transformer unchanged.

[0052] From the above analysis, it can be seen that the magnetically controlled voltage-stabilizing transformer can only transfer the voltage that is higher than the design value to both ends of the magnetically controlled reactor, while maintaining the stability of the primary voltage of the transformer. If the system voltage, that is, the input voltage U i When the voltage is lower than the specified value, the magnetically controlled voltage stabilizing transformer cannot play a voltage stabilizing role. In order to solve this problem, when designing the magnetically controlled voltage stabilizing transformer, the lowest value of the system voltage should be used as the input voltage U of the magnetically controlled voltage stabilizing transformer. i For example, the minimum voltage value of a 10kV system is 10-10×7%=9.3kV, and the minimum voltage value of a 35kV system is 35-35×5%=33.25kV. Therefore, the rated input voltage U of the magnetically controlled voltage-stabilizing transformer of a 10kV system is i =9.3kV-minimum voltage drop of magnetically controlled reactor,

[0053] The rated input voltage of the magnetically controlled voltage-stabilizing transformer of the 35kV system is U i =33.25kV-minimum voltage drop of the magnetron reactor. The "minimum voltage drop" here is determined by the design value of the magnetron reactor.

[0054] The reason why the magnetically controlled voltage-stabilizing transformer can stabilize the output voltage by itself is due to the structural design of the magnetically controlled voltage-stabilizing transformer. The magnetically controlled voltage-stabilizing transformer is composed of a magnetically controlled inductor and a transformer in series. Since the impedance of the magnetically controlled inductor is adjustable, the voltage drop of the magnetically controlled inductor is adjustable. When the system voltage (i.e., the input voltage U i ) increases or decreases, the impedance of the magnetically controlled reactor changes accordingly, and the voltage U LThe voltage change of the system is also changed, and the change of the system voltage is transferred to both ends of the magnetically controlled reactor, thereby maintaining the primary voltage U T The voltage of the transformer is kept constant, thus achieving the stability of the input / output voltage of the transformer and achieving the purpose of stabilizing the output voltage. This combination enables the power transformer to have a voltage stabilization function, improves the power transmission quality of the transformer, and improves the stability of the power supply.

[0055] The impedance adjustment range and voltage regulation capability of the magnetically controlled voltage-stabilizing transformer are determined by the impedance adjustment characteristics of the magnetically controlled reactor. The impedance of the magnetically controlled reactor can change with the change of the excitation current, and there are no mechanical factors in the impedance adjustment process, so the impedance of the magnetically controlled reactor can be adjusted continuously, quickly and smoothly. The transition time from the minimum impedance to the maximum impedance or from the maximum impedance to the minimum impedance is no more than 30ms, which shows the superior regulation performance of the magnetically controlled voltage-stabilizing transformer and provides a voltage-stabilizing device that can quickly stabilize the voltage for power supply lines with frequent voltage fluctuations.

[0056] The State Grid Corporation of China stipulates that the voltage fluctuation range of the 10kV system is ±7%, that is, 9.3kV~10.7kV; the voltage fluctuation range of the 35kV system is ±5%, that is, 33.25kV~36.75kV; the voltage fluctuation range of the 0.4kV low voltage system is ±10, that is, 0.36kV~0.44kV.

[0057] The working voltage of magnetic control voltage-stabilizing transformers is greater than the voltage fluctuation range allowed by the country. For single-phase low-voltage magnetic control voltage-stabilizing transformers, the output voltage can be stabilized at the rated value within the input voltage range of 220V±20%, that is, within the range of 176~264V; for three-phase low-voltage magnetic control voltage-stabilizing transformers, the output voltage can be stabilized at the rated value within the input voltage range of 380V±20%, that is, within the range of 304~456V; for 10kV three-phase magnetic control voltage-stabilizing transformers, the output voltage can be stabilized at the rated value within the input voltage range of 10kV±10%, that is, within the range of 9~11kV; for 35kV three-phase magnetic control voltage-stabilizing transformers, the output voltage can be stabilized at the rated value within the input voltage range of 35kV±7%, that is, within the range of 32.5~37.5kV.

[0058] Since the working winding N of the magnetically controlled reactor L and the primary winding N of the transformer T The two phases are connected in series, which is equivalent to two reactance elements being connected in series, and they provide overcurrent protection for each other. The input voltage of the transformer will not be over-voltage or over-current impact, thus improving the reliability of the magnetically controlled voltage-stabilized transformer.

[0059] Because the terminal voltage U of the magnetron reactor L L is the system voltage U iThe maximum value of the transformer T rated input voltage U T The difference is very small compared with the system voltage. When the same current flows through the primary winding of the transformer T, the capacity of the magnetically controlled reactor L corresponding to the voltage of 35kV to 0.22kV and the proportion of the capacity of the transformer T are as follows:

[0060] 1) For the magnetically controlled voltage-stabilizing transformer of the 35 kV system, the ratio of the capacity of the magnetically controlled reactor L to the capacity of the transformer T is (37.5-32.5)i / 32.5i=0.15, accounting for 15%;

[0061] 2) For the magnetically controlled voltage-stabilizing transformer of the 10 kV system, the ratio of the capacity of the magnetically controlled reactor L to the capacity of the transformer T is (11-9)i / 9i=0.22, accounting for 22%;

[0062] 3) For the magnetically controlled voltage-stabilizing transformer of the 0.4 kV system, the ratio of the capacity of the magnetically controlled reactor L to the capacity of the transformer T is (456-304)i / 304i=0.16i / 0.32i=0.5, accounting for 50%;

[0063] 4) For the magnetically controlled voltage-stabilizing transformer of the 0.22 kV system, the ratio of the capacity of the magnetically controlled reactor L to the capacity of the transformer T is (264-176)i / 176i=0.5, accounting for 50%.

[0064] It can be seen that in the magnetically controlled voltage-stabilized transformer, the capacity of the magnetically controlled reactor is much smaller than that of the transformer. When the magnetically controlled voltage-stabilized transformer is used as a 10kV or 35kV distribution transformer, the increase in its equipment cost is not large.

[0065] In the present invention, the excitation system of the magnetically controlled voltage-stabilizing transformer adopts a DC chopping working mode, and an IGBT element is used as a chopper tube. The chopping frequency is increased from several hundred hertz of thyristor excitation to several thousand hertz, and the dynamic response time of the magnetically controlled voltage-stabilizing transformer is reduced from several hundred milliseconds to less than 30 milliseconds. In addition, the voltage stabilization accuracy of the magnetically controlled voltage-stabilizing transformer is improved by adopting advanced sampling technology and a fast calculation method.

Claims

1. A voltage stabilizing transformer based on a magnetically controlled reactor, characterized in that: It includes three parts: a magnetically controlled reactor, a transformer and an excitation unit, wherein one end of the working winding of the magnetically controlled reactor is connected to one end of the primary winding of the transformer to form a series structure, forming the body of the magnetically controlled voltage-stabilizing transformer; the other end of the working winding of the magnetically controlled reactor and the other end of the primary winding of the transformer are connected to the power supply as the voltage input end of the magnetically controlled voltage-stabilizing transformer; the secondary side of the transformer includes two windings, one is a load driving winding, and the other provides excitation voltage and excitation current for the magnetically controlled reactor through the excitation unit EXC; The excitation unit includes an excitation module and a detection and protection module, wherein the excitation module includes a rectifier circuit, a filter capacitor, a central processing unit, a pulse width modulator and an IGBT chopper tube; the two output ends of the first secondary winding of the transformer are respectively connected to the anodes of the first and second rectifier diodes, and the cathodes of the first and second rectifier diodes are connected in parallel to form a full-wave rectifier circuit, and the center tap of the first secondary winding of the transformer is used as the common end of the excitation circuit; a filter capacitor is provided between the cathode common end of the first and second rectifier diodes and the ground terminal; the cathodes of the first and second rectifier diodes are connected to ... The common end is connected to the three-terminal integrated voltage regulator after resistor voltage division, and the output end of the three-terminal integrated voltage regulator is connected to the working power supply end of the central processing unit and the pulse width modulator; an IGBT chopper tube is used as a chopper element, and the central processing unit and the pulse width modulator are used as controllers to form a DC chopper circuit, the output end of the central processing unit is connected to the enable end of the pulse width modulator, the output end of the pulse width modulator is connected to the gate of the IGBT chopper tube, the emitter of the IGBT chopper tube is connected to one end of the winding of the magnetically controlled inductor, and the other end of the winding is connected to the common end of the first secondary winding of the transformer.

2. The voltage-stabilizing transformer based on the magnetically controlled reactor according to claim 1, characterized in that: The detection and protection module includes an overcurrent protection circuit and an overvoltage protection circuit, wherein the overcurrent protection circuit includes a current transformer and a central processing unit, the current transformer is arranged on the second secondary winding of the transformer, one end of its output is connected to the common end of the first winding of the transformer, and the other end is connected to the current signal input end of the central processing unit; the overvoltage protection circuit includes a voltage transformer and a central processing unit, the high-voltage input end of the voltage transformer is directly connected in parallel to the input voltage ends of the magnetically controlled voltage-stabilizing transformer, one end of the voltage transformer output end is connected to the common end of the first secondary winding of the transformer, and the other end is connected to the voltage signal input end of the central processing unit; the pulse width modulation signal output end of the central processing unit is connected to the control end of the pulse width modulator.

3. The voltage-stabilizing transformer based on the magnetically controlled reactor according to claim 1, characterized in that: There are two types of structures: single-phase structure and three-phase structure. The single-phase structure is composed of a single-phase magnetically controlled inductor and a single-phase transformer in series, and the three-phase magnetically controlled voltage-stabilizing transformer is composed of each phase of a three-phase magnetically controlled inductor and each phase of a three-phase transformer in series. The secondary side of each phase of the transformer provides the excitation voltage and excitation current for the corresponding phase of the magnetically controlled inductor through the excitation unit of each phase.

4. The voltage-stabilizing transformer based on a magnetically controlled reactor according to claim 1, characterized in that: The magnetically controlled reactor, transformer and excitation unit are of a common box type or a split type structure.

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