A magnetic control transformer

Abstract

The application discloses a device, comprising: a magnetic control transformer, comprising: three adjacent core assemblies arranged in a regular triangle; first coils wound on the sides of any two adjacent core assemblies close to each other; each core assembly comprising an upper yoke and a lower yoke, the upper yoke and the lower yoke being wound with second coils respectively; and a bipolar magnetic valve arranged beside each second coil. In the application, the bipolar magnetic valve is used to reduce the harmonic content of the output current of the magnetic control transformer, which is different from the method of external suppression and other methods requiring additional harmonic control devices, and has the advantages of low cost and simple structure.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, and more particularly to a magnetically controlled transformer. Background Technology

[0002] With an increasing proportion of new energy sources being integrated into the power system, the voltage at the power system's terminals becomes unstable and fluctuates. Under light loads, the terminal voltage can easily rise and even exceed the allowable range of the power system. To address this, a magnetic valve-type magnetically controlled transformer was proposed, combining a transformer with a magnetically controlled reactor to compensate for reactive power and maintain voltage stability. However, based on the principle of core magnetic saturation, the magnetic valve-type magnetically controlled transformer inevitably generates high-order harmonics during dynamic adjustment. As the capacity of the magnetically controlled transformer increases, the harmonic content of the output also increases, and excessively high harmonics can harm the power system. Summary of the Invention

[0003] This invention provides a magnetically controlled transformer that solves the technical problem that magnetically controlled transformers inevitably generate high-order harmonics during dynamic adjustment, and that excessively high harmonics can harm the power system.

[0004] The present invention provides a magnetically controlled transformer, comprising: three adjacent iron core assemblies, the three iron core assemblies being arranged in an equilateral triangle;

[0005] The first coil is wound on the side body of any two adjacent iron core assemblies that are close to each other;

[0006] Each of the aforementioned core assemblies includes an upper side yoke and a lower side yoke, and the upper side yoke and the lower side yoke are respectively wound with a second coil;

[0007] A bipolar solenoid valve is provided next to each of the second coils.

[0008] Preferably, each of the said core assemblies further includes two iron cores disposed opposite to each other;

[0009] Each of the aforementioned iron cores includes a first side body and a second side body and a third side body that are perpendicular to the upper and lower sides of the first side body, respectively.

[0010] Preferably, the upper yoke is fixedly disposed on the top of the second side body of the two oppositely disposed iron cores; the lower yoke is fixedly disposed on the top of the third side body of the two oppositely disposed iron cores.

[0011] Preferably, both the upper lateral yoke and the lower lateral yoke include a fourth lateral body and a fifth lateral body and a sixth lateral body that are perpendicular to the left and right sides of the fourth lateral body, respectively.

[0012] The fifth and sixth side bodies of the upper yoke are respectively vertically arranged on the top of the second side bodies of the two oppositely arranged iron cores;

[0013] The fifth and sixth side bodies of the lower yoke are respectively vertically arranged on top of the third side bodies of the two oppositely arranged iron cores.

[0014] Preferably, gaps are left between the second side bodies and the third side bodies of the two oppositely arranged iron cores, and the bipolar solenoid valve is disposed at the gaps.

[0015] Preferably, the bipolar solenoid valve includes a small cross-section section and two medium cross-section sections disposed on both sides of the small cross-section section.

[0016] Preferably, the sum of the lengths of the two intermediate sections is the same as the length of the smaller section;

[0017] The second side body and the third side body have the same first cross-sectional area, the second cross-sectional area of ​​the small cross-section is one-third of the first cross-sectional area, and the third cross-sectional area of ​​the middle cross-section is two-thirds of the first cross-sectional area.

[0018] Preferably, the first coil is an AC coil; the AC coil is wound around the first side of two adjacent iron cores.

[0019] Preferably, the second coil is a DC coil; the DC coil is wound around the fourth side body of each yoke.

[0020] Preferably, both the upper and lower side yokes are U-shaped side yokes; and the iron core is a U-shaped iron core.

[0021] As can be seen from the above technical solutions, the present invention has the following advantages:

[0022] This invention provides a magnetically controlled transformer, comprising: three adjacent core assemblies arranged in an equilateral triangle; a first coil wound around the sides of any two adjacent core assemblies; each core assembly includes an upper yoke and a lower yoke, with a second coil wound around each yoke; and a bipolar solenoid valve disposed next to each second coil. In this invention, a bipolar solenoid valve is used to reduce the harmonic content of the output current of the magnetically controlled transformer. Unlike external suppression methods that require additional harmonic control devices, this method is low-cost and simple in structure, thus solving the technical problem that magnetically controlled transformers inevitably generate high-order harmonics during dynamic adjustment, and that excessively high harmonics can harm the power system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This application provides an overall schematic diagram of a magnetically controlled transformer;

[0025] Figure 2 A schematic diagram of the bipolar solenoid valve provided in this application;

[0026] Figure 3 An equivalent plot of the magnetization characteristics of the bipolar solenoid valve provided in this application in the simulation curve;

[0027] The attached diagram is labeled as follows: iron core 1, upper yoke 2, lower yoke 3, bipolar solenoid valve 4, small cross-section section 41, medium cross-section section 42, first coil 5, and second coil 6. Detailed Implementation

[0028] This invention provides a magnetically controlled transformer to solve the technical problem that magnetically controlled transformers inevitably generate high-order harmonics during dynamic adjustment, and that excessively high harmonics can harm the power system.

[0029] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Please see Figure 1An embodiment of a magnetically controlled transformer provided in this application includes: three adjacent core assemblies arranged in an equilateral triangle; a first coil 5 is wound around the sides of any two adjacent core assemblies that are close to each other; each core assembly includes an upper yoke 2 and a lower yoke 3, and a second coil 6 is wound around the upper yoke 2 and the lower yoke 3 respectively; a bipolar solenoid valve 4 is provided next to each second coil 6.

[0033] In this embodiment, the arrangement of the three core components in an equilateral triangle can reduce the harmonics of the magnetically controlled transformer, and the use of the bipolar magnetic valve 4 can further limit the harmonic content of the magnetically controlled transformer.

[0034] In a preferred embodiment, each core assembly further includes two opposing cores 1; each core 1 includes a first side body and a second side body and a third side body that are perpendicular to the upper and lower sides of the first side body, respectively.

[0035] In a preferred embodiment, the upper yoke 2 is fixedly disposed on the top of the second side body of the two oppositely disposed iron cores 1; the lower yoke 3 is fixedly disposed on the top of the third side body of the two oppositely disposed iron cores 1.

[0036] In a preferred embodiment, both the upper yoke 2 and the lower yoke 3 include a fourth side body and a fifth side body and a sixth side body that are perpendicular to the left and right sides of the fourth side body, respectively; the fifth side body and the sixth side body of the upper yoke 2 are respectively vertically disposed on the top of the second side body of the two oppositely disposed iron cores 1; the fifth side body and the sixth side body of the lower yoke 3 are respectively vertically disposed on the top of the third side body of the two oppositely disposed iron cores 1.

[0037] In a preferred embodiment, gaps are left between the second side bodies and the third side bodies of the two oppositely arranged iron cores 1, and the bipolar solenoid valve 4 is disposed at the gap.

[0038] It is understandable that the bipolar solenoid valve 4 is located within the gap, and the bipolar solenoid valve 4 is fixedly connected to two oppositely arranged iron cores 1.

[0039] In a preferred embodiment, the first coil 5 is an AC coil; the AC coil is wound around the first side body of two adjacent iron cores 1.

[0040] It should be noted that the three first coils 5 wound in the magnetically controlled transformer correspond to the three-phase currents respectively. The high and low voltage AC windings of each phase are wound on the iron core 1, which plays the role of voltage transformation.

[0041] In a preferred embodiment, the second coil 6 is a DC coil; the DC coil is wound around the fourth side body of each yoke.

[0042] A DC excitation coil is wound on the yoke. Since the bipolar solenoid valve 4 is close to the upper yoke 2 or the lower yoke 3, the magnetic flux passing through the bipolar solenoid valve 4 is a superposition of DC magnetic flux and AC magnetic flux. That is, the magnetic fields generated by the AC coil and the DC coil will both pass through the bipolar solenoid valve 4, and the magnetic flux applied to the bipolar solenoid valve 4 will achieve a superposition effect.

[0043] Specifically, within the core assembly, the DC magnetic flux generated by the upper yoke 2 and the lower yoke 3 is in the same direction. Since the current passing through the AC coil alternates between the positive and negative half cycles, the direction of the generated magnetic field also changes accordingly. Therefore, the AC magnetic flux generated by the core 1 will be superimposed on the DC magnetic flux at a certain bipolar solenoid valve 4 within the core assembly, causing the bipolar solenoid valve 4 to saturate. Meanwhile, the AC magnetic flux partially cancels out the DC magnetic flux at another bipolar solenoid valve 4, meaning that the other bipolar solenoid valve 4 is not saturated.

[0044] In other words, when the DC magnetic flux and the AC magnetic flux are in the same direction, the bipolar solenoid valve 4 will reach the magnetic saturation state; when the DC magnetic flux and the AC magnetic flux are in opposite directions, the bipolar solenoid valve 4 will be in the desaturation state. Therefore, when a magnetic flux is applied, each bipolar solenoid valve 4 switches between the magnetic saturation and desaturation states.

[0045] At any given time, there is always one bipolar solenoid valve 4 in the same core assembly that is in a saturated state. At this time, the magnetic permeability of the core assembly is small, the magnetic reluctance is large, and the corresponding inductance is small. This part of the inductance is equivalent to the magnetizing inductance in the magnetically controlled transformer, which can play the role of supplementing reactive power.

[0046] Please see Figure 2 In a preferred embodiment, the bipolar solenoid valve includes a small cross-section section 41 and two medium cross-section sections 42 disposed on both sides of the small cross-section section 41.

[0047] In a preferred embodiment, the sum of the lengths of the two mid-section segments 42 is the same as the length of the small-section segment 41; the first cross-sectional areas of the second side body and the third side body are the same, the second cross-sectional area of ​​the small-section segment 41 is one-third of the first cross-sectional area, and the third cross-sectional area of ​​the mid-section segment 42 is two-thirds of the first cross-sectional area.

[0048] It should be noted that the output current of the magnetically controlled transformer contains certain harmonics, with the third harmonic being the most prevalent. During the operation of the magnetically controlled transformer, the bipolar solenoid valve undergoes bipolar saturation. The small cross-section section 41 and the medium cross-section section 42 contribute differently to the output current, thus suppressing the harmonic current. Bipolar saturation refers to the fact that under rated operating voltage, without any DC magnetic flux, the small cross-section section 41 enters a saturated state and remains saturated throughout the subsequent control process. The larger medium cross-section section 42 is initially unsaturated. As the DC excitation current increases, when the medium cross-section section 42 also enters a saturated state, the medium cross-section section 42 and the small cross-section section 41 will generate harmonics in opposite directions, canceling each other out and reducing the harmonic components in the output current of the magnetically controlled transformer.

[0049] The cross-sectional area of ​​this preferred embodiment is the cross-sectional area of ​​a section obtained perpendicular to the axis of the magnetically controlled transformer;

[0050] Specifically, the first cross-sectional area of ​​the iron core 1 is A1. In the bipolar solenoid valve, the second cross-sectional area of ​​the small cross-section 41 is A2, and the third cross-sectional area of ​​the middle cross-section 42 is A3. The length of the small cross-section 41 is l1, and the sum of the lengths of the two middle cross-sections 42 is l2. To facilitate the analysis of the magnetic field strength of the bipolar solenoid valve, an equivalent magnetic field strength He is introduced. The magnetization characteristics of the bipolar solenoid valve in the simulation curve are set as follows: Figure 3 As shown, according to Ampere's circuital law, we get

[0051] H e (l1+l2)=H1l1+H2l2 (1)

[0052] In the formula, H1 and H2 are the magnetic field strengths in the small cross-section segment 41 and the medium cross-section segment 42, respectively. Analysis shows that He is a piecewise function. By changing the ratio of the cross-sectional area and length of the small cross-section segment 41 and the medium cross-section segment 42, the magnetization characteristics of the bipolar solenoid valve can be changed equivalently. Analysis shows that the harmonic current of the magnetically controlled transformer is equivalent to the superposition of the harmonics generated by the small cross-section segment 41 and the medium cross-section segment 42.

[0053] Let L t1 =l1 / (l1+l2), L t2 = l2 / (l1+l2), where L t1 The proportion of the core of the small cross-section section 41 to the core of the bipolar solenoid valve, L t2 The proportion of the core of the two mid-section sections 42 to the core of the bipolar solenoid valve;

[0054] Combining equation (1), we can obtain the expressions for the fundamental frequency and each harmonic:

[0055]

[0056] In the formula, This is the per-unit value of the fundamental current; Let n be the per-unit value of each harmonic current, n = 1, 2, ...; β1 and β2 are the magnetic saturation of the small cross-section 41 and the two medium cross-sections 42, respectively.

[0057] The inflection points Bs1 and Bs2 of the equivalent magnetization curve of the bipolar solenoid valve are determined by the cross-sectional area relationship between the small cross-section segment 41 and the medium cross-section segment 42. Bs1 and Bs2 are the magnetic induction intensity saturation values ​​corresponding to the small cross-section segment 41 and the medium cross-section segment 42, respectively. In the structural design of the bipolar solenoid valve, when the design satisfies A2 = 1 / 3A1 and A3 = 2 / 3A1, we have Bs1 = (1 / 3)*Bts and Bs2 = (2 / 3)*Bts. Among them, Bts is the magnetic induction intensity saturation value corresponding to the bipolar solenoid valve.

[0058] When the DC excitation flux of the bipolar solenoid valve is increased, the magnetic saturation of the small section 41 and the medium section 42 will automatically satisfy the following relationship: when β1≤π, β2=0; when π<β1≤2π, cos(β1 / 2)=1-cos(β2 / 2). Analysis shows that the phase of the third harmonic generated by the small section 41 is opposite to the phase of the third harmonic generated by the medium section 42, and they cancel each other out.

[0059] Therefore, when the bipolar solenoid valve satisfies A2 = 1 / 3A1, A3 = 2 / 3A1, and l1 = l2, the middle section 42 and the small section 41 will generate third harmonics of basically equal magnitude but opposite direction. The harmonic currents superimpose each other, reducing the third harmonic in the output current of the final magnetically controlled transformer. The bipolar solenoid valve also plays a limiting role for higher harmonics such as the fifth and seventh orders.

[0060] In particular, the cross-sections of the small cross-section 41 and the medium cross-section 42 used in this preferred embodiment are both square. Compared with the circular cross-section, the magnetic flux flowing through the cross-section of the bipolar solenoid valve with the square cross-section is more uniform and does not waste the cross-sectional area, which can reduce the amount of core material used and reduce costs.

[0061] In this preferred embodiment, the bipolar solenoid valve can reduce the output harmonics of the magnetically controlled transformer. At the same time, the rationally designed bipolar solenoid valve structure can also reduce the edge effect when the magnetic saturation is reached and reduce winding losses. The magnetically controlled transformer using the bipolar solenoid valve can reduce the impact of harmonics on the power system and the limitation of rated capacity.

[0062] In a preferred embodiment, both the upper yoke 2 and the lower yoke are U-shaped yokes; the iron core 1 is a U-shaped iron core.

[0063] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetically controlled transformer, characterized in that, include: Three adjacent core assemblies, the three core assemblies being arranged in an equilateral triangle; The first coil is wound on the side body of any two adjacent iron core assemblies that are close to each other; Each of the aforementioned core assemblies includes an upper side yoke and a lower side yoke, and the upper side yoke and the lower side yoke are respectively wound with a second coil; A bipolar solenoid valve is provided next to each of the second coils; The bipolar solenoid valve includes a small cross-section section and two medium cross-section sections disposed on both sides of the small cross-section section.

2. The magnetically controlled transformer according to claim 1, characterized in that, Each of the aforementioned core assemblies further includes two iron cores disposed opposite to each other; Each of the aforementioned iron cores includes a first side body and a second side body and a third side body that are perpendicular to the upper and lower sides of the first side body, respectively.

3. The magnetically controlled transformer according to claim 2, characterized in that, The upper yoke is fixedly disposed on the top of the second side body of the two oppositely disposed iron cores; the lower yoke is fixedly disposed on the top of the third side body of the two oppositely disposed iron cores.

4. The magnetically controlled transformer according to claim 2, characterized in that, Both the upper lateral yoke and the lower lateral yoke include a fourth lateral body and a fifth lateral body and a sixth lateral body that are perpendicular to the left and right sides of the fourth lateral body, respectively. The fifth and sixth side bodies of the upper yoke are respectively vertically arranged on the top of the second side bodies of the two oppositely arranged iron cores; The fifth and sixth side bodies of the lower yoke are respectively vertically arranged on top of the third side bodies of the two oppositely arranged iron cores.

5. The magnetically controlled transformer according to claim 2, characterized in that, There are gaps between the second and third side bodies of the two opposing iron cores, and the bipolar solenoid valve is located at the gaps.

6. The magnetically controlled transformer according to claim 3, characterized in that, The sum of the lengths of the two intermediate sections is the same as the length of the smaller section; The second side body and the third side body have the same first cross-sectional area, the second cross-sectional area of ​​the small cross-section is one-third of the first cross-sectional area, and the third cross-sectional area of ​​the middle cross-section is two-thirds of the first cross-sectional area.

7. The magnetically controlled transformer according to claim 2, characterized in that, The first coil is an AC coil; the AC coil is wound around the first side of two adjacent iron cores.

8. The magnetically controlled transformer according to claim 4, characterized in that, The second coil is a DC coil; the DC coil is wound around the fourth side body of each side yoke.

9. The magnetically controlled transformer according to claim 2, characterized in that, Both the upper and lower side yokes are U-shaped side yokes; the iron core is a U-shaped iron core.

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