Voltage regulation method for high voltage side of autotransformer, body structure and autotransformer

Abstract

The present invention discloses a method for regulating the high-voltage side of an autotransformer, comprising: winding a low-voltage winding, a tap winding, and a common winding on a common constant-flux core leg; winding an excitation winding and a series winding on a common variable-flux core leg; connecting the series winding in series with the common winding, connecting the excitation winding and the tap winding in series, and then connecting them in parallel with the low-voltage winding; adjusting the number of turns of the tap winding to change the voltage of the excitation winding on the variable-flux core leg, thereby causing the voltage of the series winding on the same variable-flux core leg to change accordingly, thereby regulating the high-voltage side of the autotransformer. Also provided are an autotransformer body structure and an autotransformer. This method uses a low-voltage tap changer to regulate the voltage of the high-voltage side winding, thereby reducing the manufacturing difficulty of the tap changer and the cost of the transformer.

Description

Technical Field

[0001] The present invention belongs to the technical field of transformers, and in particular relates to a voltage regulation method for a high-voltage side of an autotransformer, a body structure and an autotransformer. Background Art

[0002] Autotransformers are widely used in power systems due to their cost-effectiveness and energy efficiency. Autotransformers typically connect the high-voltage and medium-voltage windings in an autocoupled manner. The corresponding high-voltage side coil is generally referred to as the series winding, while the corresponding medium-voltage side coil is referred to as the common winding. To accommodate voltage fluctuations on the high-voltage side of the grid, a tap winding is typically connected in series with the series or common winding. Voltage regulation is achieved by adjusting the number of turns in the tap winding.

[0003] The current voltage regulation technology of autotransformers often adopts the following solutions:

[0004] (1) The variable flux voltage regulation method that regulates voltage at the neutral point (i.e., with a tapped winding at the end of the common winding) has a relatively large voltage regulation capacity and a large step capacity of the voltage regulator, making it difficult to select the voltage regulator and resulting in high switch procurement costs. In addition, this variable flux voltage regulation method can cause large voltage fluctuations in the low-voltage winding. If the transformer's low-voltage winding is equipped with a reactive compensation device or is loaded, additional compensation coils are required to stabilize the voltage of the low-voltage winding, further increasing manufacturing costs and difficulty.

[0005] (2) Voltage regulation at the end of the series coil: A tap coil is connected to the end of the series coil, and the high-voltage side voltage is adjusted by adjusting the number of turns of the tap coil. The disadvantages of this voltage regulation method are: the tap coil and tap changer are at extremely high voltage, the insulation structure is extremely complex, the tap changer needs to be specially customized, and the overall safety margin is low. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a voltage regulation method for the high-voltage side of an autotransformer, a body structure, and an autotransformer. By using a low-voltage tap changer for voltage regulation, the manufacturing difficulty of the tap changer can be reduced, thereby reducing the cost of the transformer.

[0007] To achieve the above objectives, in a first aspect, an embodiment of the present invention provides a method for regulating voltage on the high-voltage side of an autotransformer, the method comprising the following steps:

[0008] The low-voltage winding, the tap winding and the common winding are respectively wound on the same constant flux iron core leg; the excitation winding and the series winding are respectively wound on the same variable flux iron core leg; the series winding is connected in series with the common winding, and the excitation winding and the tap winding are connected in series and then in parallel with the low-voltage winding; the number of turns of the tap winding is adjusted to change the voltage of the excitation winding on the variable flux iron core leg, so that the voltage of the series winding on the same variable flux iron core leg is changed accordingly, thereby achieving voltage regulation on the high-voltage side of the autotransformer.

[0009] Preferably, the excitation winding and the series winding are wound on the variable flux core column in sequence from inside to outside.

[0010] Preferably, the number of the constant flux core columns is identical, the winding order of the low voltage winding, the tap winding and the common winding on each constant flux core column is the same, and the number of the variable flux core column is one.

[0011] Preferably, the connection method of each low-voltage winding on each constant magnetic flux core column is: connect each low-voltage winding in series in sequence; or, connect each low-voltage winding in parallel in sequence, and make the number of turns of each low-voltage winding the same; the connection method of each tap winding on each constant magnetic flux core column is: connect each tap winding in series in sequence; or, connect each tap winding in parallel in sequence, and make the number of turns of each tap winding the same; the connection method of each common winding on each constant magnetic flux core column is: connect each common winding in series in sequence; or, connect each common winding in parallel in sequence, and make the number of turns of each common winding the same.

[0012] In a second aspect, an embodiment of the present invention provides a body structure of an autotransformer, comprising an iron core and a winding unit, wherein the iron core comprises a variable magnetic flux iron core column and a constant magnetic flux iron core column, and the winding unit comprises a series winding, a common winding, a low-voltage winding, a tap winding and an excitation winding, wherein the excitation winding and the series winding are respectively wound on the same said variable magnetic flux iron core column, and the low-voltage winding, the tap winding and the common winding are respectively wound on the same said constant magnetic flux iron core column, wherein the series winding is connected in series with the common winding, the excitation winding is connected in series with the tap winding, and the series structure formed by the excitation winding and the tap winding is connected in parallel with the low-voltage winding.

[0013] Preferably, the excitation winding and the series winding are wound on the variable flux core column in sequence from inside to outside.

[0014] Preferably, the number of the constant magnetic flux core columns is exactly the same, the winding order of the low-voltage winding, tap winding and common winding on each constant magnetic flux core column is the same, the number of the variable magnetic flux core columns is one, and on each constant magnetic flux core column, each low-voltage winding is connected in series in sequence, or each low-voltage winding is connected in parallel in sequence, and the number of turns of each low-voltage winding is the same; or each tap winding is connected in series in sequence, or each tap winding is connected in parallel in sequence, and the number of turns of each tap winding is the same; or each common winding is connected in series in sequence, or each common winding is connected in parallel in sequence, and the number of turns of each common winding is the same.

[0015] Preferably, the series winding adopts a parallel structure with a middle input line and upper and lower output lines; the common winding adopts a parallel structure with a middle input line and upper and lower output lines.

[0016] Preferably, the iron core adopts a four-column iron core, which includes two main columns, two side columns, and an upper iron yoke and a lower iron yoke, the two main columns are respectively a constant magnetic flux iron core column and a variable magnetic flux iron core column, and the two side columns are respectively arranged on the outside of the two main columns, or the iron core adopts a five-column iron core, which includes three main columns, two side columns, and an upper iron yoke and a lower iron yoke, the three main columns are respectively a variable magnetic flux iron core column and two constant magnetic flux iron core columns, and the two side columns are respectively arranged on the outside of the three main columns.

[0017] In a third aspect, an embodiment of the present invention provides an autotransformer, comprising the autotransformer body structure described in the second aspect.

[0018] In the voltage regulation method for the high-voltage side of an autotransformer provided in an embodiment of the present invention, the excitation winding and the tap winding are connected in series and then connected in parallel with the low-voltage winding. Since the voltage of the low-voltage winding is constant, the voltage of the excitation winding on the variable flux core leg is changed by adjusting the number of turns of the tap winding, so that the voltage of the series winding on the same variable flux core leg changes accordingly, thereby achieving voltage regulation on the high-voltage side of the autotransformer. Since the series structure formed by the excitation winding and the tap winding is connected in parallel with the low-voltage winding, the voltage borne by the tap winding is close to the voltage level of the low-voltage winding. Therefore, a low-voltage tap changer can be used for voltage regulation, reducing the manufacturing difficulty of the tap changer, improving the safety of the switch operation, and reducing the cost of the transformer. In addition, the body structure and autotransformer provided in an embodiment of the present invention integrate the constant flux core leg and the variable flux core leg on the same core, reducing the internal geometric dimensions of the transformer oil tank, saving the amount of transformer oil and steel parts, and further reducing the cost of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : A wiring schematic diagram of a voltage regulation method for the high-voltage side of an autotransformer according to embodiment 1 of the present invention;

[0020] Figure 2 : A schematic diagram of the body structure of an autotransformer according to embodiment 2 of the present invention;

[0021] Figure 3 : An autotransformer body structure (using a single-phase four-pillar core) according to Example 2 of the present invention;

[0022] Figure 4 : The body structure of an autotransformer according to embodiment 2 of the present invention (using a single-phase five-column iron core).

[0023] In the figure: 1-series winding; 2-excitation winding; 3-tap winding; 4-low voltage winding; 5-common winding; 6-side column; 7-constant magnetic flux core column; 8-variable magnetic flux core column. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1:

[0026] This embodiment provides a voltage regulation method for the high-voltage side of an autotransformer, which is applied to an autotransformer, such as Figure 1 The figure shows the wiring principle diagram of the autotransformer. The voltage regulation method includes the following steps:

[0027] Step 101: Wind the low voltage winding 4, the tap winding 3 and the common winding 5 on the same constant magnetic flux core leg.

[0028] The order in which the low-voltage winding 4 , the tap winding 3 and the common winding 5 are wound on the same constant magnetic flux core leg can be determined according to user requirements.

[0029] Step 102: Wind the excitation winding 2 and the series winding 1 on the same variable flux core column.

[0030] Step 103 , connecting the series winding 1 and the common winding 5 in series, connecting the excitation winding 2 and the tap winding 3 in series, and then connecting them in parallel with the low-voltage winding 4 .

[0031] The series winding 1 and the common winding 5 are connected in series to form the high voltage side of the autotransformer.

[0032] Step 104 , by adjusting the number of turns of the tap winding 3 , the voltage of the excitation winding on the variable flux core leg is changed, so that the voltage of the series winding 1 on the same variable flux core leg is changed accordingly, thereby achieving voltage regulation on the high voltage side of the autotransformer.

[0033] In this embodiment, the tap winding 3 is connected to the tap changer such that one end of the tap changer is connected to the excitation winding 2, the other end of the tap changer is connected to the low-voltage winding 4, and the other end of the excitation winding 2 is connected to the other end of the low-voltage winding 4. It should be noted that, viewed from the beginning and end terminals of the low-voltage winding 4, a structure is formed in which the excitation winding 2 is connected in series with the tap winding 3 and then in parallel with the low-voltage winding 4. Alternatively, a structure is also formed in which the low-voltage winding 4 is connected in series with the tap winding 3 and then in parallel with the excitation winding 2. Both situations essentially have the same circuit structure, differing only in the description method.

[0034] Since the voltage value of the excitation winding 2 and the tap winding 3 connected in series is the same as the voltage of the low-voltage winding 4, and the voltage output by the low-voltage winding 4 is constant, by adjusting the number of turns connected in the tap winding 3 (that is, changing the contact position of the tap changer), the voltage difference between the head and end of the excitation winding 2 connected in series with the tap winding 3 will change. Due to the principle of electromagnetic induction, it can be known that the voltage of the series winding 1 on the same variable flux core leg as the excitation winding 2 will also change accordingly. This change is the voltage regulation range of the series winding 1, which is generally between plus and minus 15%.

[0035] Optionally, the excitation winding 2 and the series winding 1 are wound on the variable flux core column in sequence from inside to outside.

[0036] Optionally, the number of constant flux core legs is identical, the low-voltage winding, tap winding, and common winding on each constant flux core leg are wound in the same order, and the number of variable flux core legs is one. When the number of constant flux core legs is identical, parameters such as size, material, and cross-sectional area of ​​the constant flux core legs are identical, and the winding order on each constant flux core leg is identical. Selecting an identical number of constant flux core legs and winding them in the same order helps expand the capacity of the transformer.

[0037] Optionally, the connection method of each low-voltage winding on each constant magnetic flux core column is: connect each low-voltage winding in series in sequence; or, connect each low-voltage winding in parallel in sequence, and make the number of turns of each low-voltage winding the same; the connection method of each tap winding on each constant magnetic flux core column is: connect each tap winding in series in sequence; or, connect each tap winding in parallel in sequence, and make the number of turns of each tap winding the same; the connection method of each common winding on each constant magnetic flux core column is: connect each common winding in series in sequence; or, connect each common winding in parallel in sequence, and make the number of turns of each common winding the same.

[0038] In this embodiment, when the number of constant magnetic flux core legs is exactly the same, the winding order of the low-voltage winding, the tap winding, and the common winding on each constant magnetic flux core leg is the same, and different connections between the same windings can be performed according to the requirements of the design parameters. For example, the low-voltage windings on the two constant magnetic flux core legs can be connected in series, wherein the two low-voltage windings have the same number of turns, and the tap windings on the two constant magnetic flux core legs can be connected in series, wherein the two tap windings have the same number of turns, and then the common windings on the two constant magnetic flux core legs can be connected in parallel, wherein the two common windings have the same number of turns.

[0039] Example 2:

[0040] like Figure 2 As shown, this embodiment provides a body structure of an autotransformer, which is mainly applicable to single-phase autotransformers. The body structure includes an iron core and a winding unit. The iron core includes a variable magnetic flux iron core column 8 and a constant magnetic flux iron core column 7. The winding unit includes a series winding 1, a common winding 5, a low-voltage winding 4, a tap winding 3 and an excitation winding 2. The excitation winding 2 and the series winding 1 are respectively wound on the same variable magnetic flux iron core column 8, and the low-voltage winding 4, the tap winding 3 and the common winding 5 are respectively wound on the same constant magnetic flux iron core column 7. Among them, the series winding 1 is connected in series with the common winding 5, the excitation winding 2 is connected in series with the tap winding 3, and the series structure formed by the excitation winding 2 and the tap winding 3 is connected in parallel with the low-voltage winding 4.

[0041] In this embodiment, the tapped winding 3 is connected to the tap changer. Since the voltage value of the excitation winding 2 connected in series with the tapped winding 3 should be the same as the voltage of the low-voltage winding 4, and the voltage output by the low-voltage winding 4 is constant, by adjusting the number of turns of the tapped winding 3 (i.e., changing the contact position of the tap changer), the voltage difference between the head and end of the excitation winding 2 connected in series with the tapped winding 3 will change. Due to the principle of electromagnetic induction, the voltage of the series winding 1 on the same variable flux core leg as the excitation winding 2 will also change accordingly. This change is the voltage regulation range of the series winding, thereby achieving voltage regulation on the high-voltage side of the autotransformer with this device structure.

[0042] Because the series connection of the excitation winding 2 and the tap winding 3 is connected in parallel with the low-voltage winding 4, the voltage borne by the tap winding 3 is close to the voltage level of the low-voltage winding 4. Therefore, a low-voltage tap changer can be used for voltage regulation, which reduces the manufacturing difficulty of the tap changer, thereby reducing the cost of the transformer and improving the safety of the switch operation. Therefore, the low-voltage winding 4 in this embodiment not only meets the output voltage required by the user, but also provides power and excitation to the excitation winding 2 on the variable flux core leg.

[0043] Optionally, the excitation winding 2 and the series winding 1 are wound on the variable flux core column in sequence from inside to outside.

[0044] Optionally, the number of constant magnetic flux core columns is exactly the same, the winding order of the low-voltage winding, tap winding and common winding on each constant magnetic flux core column is the same, the number of variable magnetic flux core columns is one, and on each constant magnetic flux core column, each low-voltage winding is connected in series in sequence, or each low-voltage winding is connected in parallel in sequence, and the number of turns of each low-voltage winding is the same; or each tap winding is connected in series in sequence, or each tap winding is connected in parallel in sequence, and the number of turns of each tap winding is the same; or each common winding is connected in series in sequence, or each common winding is connected in parallel in sequence, and the number of turns of each common winding is the same.

[0045] Optionally, the series winding 1 adopts a parallel structure with a central input and upper and lower outputs; the common winding 5 adopts a parallel structure with a central input and upper and lower outputs. Because the voltage at the head end of the series winding and common winding of the autotransformer is higher than the voltage at the tail end, the central input and upper and lower output structure places the low voltage of the series winding and common winding at the upper and lower ends of the body structure. This location creates a relatively lower voltage difference with other structural components, which helps improve the insulation safety of the body structure ends and enhances the operational reliability of the transformer.

[0046] Alternatively, as Figure 3 As shown, the core adopts a four-pillar core, which includes two main pillars, two side pillars 6, and an upper iron yoke and a lower iron yoke. The two main pillars are a constant magnetic flux core pillar 7 and a variable magnetic flux core pillar 8, and the two side pillars 6 are respectively arranged on the outside of the two main pillars.

[0047] like Figure 4 As shown, the core adopts a five-column core, which includes three main columns, two side columns 6, and an upper iron yoke and a lower iron yoke. The three main columns are a variable magnetic flux core column 8 and two constant magnetic flux core columns 7, and the two side columns 6 are respectively arranged on the outside of the three main columns.

[0048] In this embodiment, by adopting a single-phase four-pillar iron core or a single-phase five-pillar iron core, the constant magnetic flux iron core column and the variable magnetic flux iron core column are integrated into the same iron core, which can effectively reduce the internal geometric dimensions of the transformer oil tank, save the amount of transformer oil and steel parts, and thus reduce the cost of the transformer.

[0049] Example 3:

[0050] This embodiment provides an autotransformer, including the autotransformer body structure described in Example 2. For example, the high-side, mid-side, and low-side voltage ratios of the autotransformer are: 400(+4, -8)*1.25% / 330 / 33(kV).

[0051] The beneficial effects of the above embodiment are:

[0052] (1) The excitation winding and the tap winding are connected in series and then in parallel with the low-voltage winding. Therefore, the voltage on the tap winding is close to the voltage level of the low-voltage winding. Therefore, a low-voltage tap changer can be selected, which greatly reduces the manufacturing difficulty of the tap changer itself and the operating risk of the switch.

[0053] (2) In the method for regulating the high-voltage side of the autotransformer provided in Example 1, the tap winding is connected in series to the tail of the low-voltage winding, so the voltage of the tap winding and the voltage regulating tap lead is very low, which greatly simplifies the insulation structure of the tap winding and the voltage regulating tap lead.

[0054] (3) The constant flux core column and the variable flux core column are integrated on the same core, which can effectively reduce the internal geometric dimensions of the transformer oil tank, save the amount of transformer oil and steel parts, and reduce the cost of the transformer.

[0055] (4) The low-voltage winding is used as an auxiliary winding to power the excitation winding, eliminating the need for a separate auxiliary winding, further saving transformer consumables and not affecting the output voltage of the low-voltage winding.

[0056] (5) The first end of the series winding and the common winding is preferably designed to be led out in the middle, and a structure of two parallel output lines is adopted, which is beneficial to improving the safety of the insulation at the end of the body structure and improving the operational reliability of the transformer.

[0057] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A voltage regulation method for the high-voltage side of an autotransformer, characterized in that: The method comprises the following steps: The low-voltage winding (4), the tap winding (3) and the common winding (5) are respectively wound on the same constant magnetic flux iron core column; The excitation winding (2) and the series winding (1) are respectively wound on the same variable flux iron core column, and the number of the variable flux iron core column is one; The series winding (1) is connected in series with the common winding (5), the exciting winding (2) is connected in series with the tap winding (3), and then connected in parallel with the low-voltage winding (4); The number of turns of the tap winding (3) is adjusted, thereby changing the voltage of the exciting winding (2) on the variable flux iron core column, so that the voltage of the series winding (1) on the same variable flux iron core column changes accordingly, thereby achieving voltage regulation on the high voltage side of the autotransformer.

2. The method according to claim 1, wherein The excitation winding (2) and the series winding (1) are wound on the variable flux core column in sequence from the inside to the outside.

3. The method according to claim 2, wherein The number of the constant magnetic flux core columns is exactly the same, and the winding order of the low voltage winding, the tap winding and the common winding on each constant magnetic flux core column is the same.

4. The method according to claim 3, wherein The connection method of each low-voltage winding on each constant magnetic flux core leg is: Connecting the low-voltage windings in series in sequence; or connecting the low-voltage windings in parallel in sequence, and making the number of turns of the low-voltage windings the same; The connection method of each tap winding on each constant magnetic flux core leg is: Connecting the tapped windings in series in sequence; or connecting the tapped windings in parallel in sequence, with the number of turns of each tapped winding being the same; The connection method of each common winding on each constant magnetic flux core leg is: The common windings are sequentially connected in series; or, the common windings are sequentially connected in parallel, and the number of turns of the common windings is the same.

5. A body structure of an autotransformer, comprising an iron core and a winding unit, characterized in that: The iron core comprises a variable magnetic flux iron core column (8) and a constant magnetic flux iron core column (7), wherein the number of the variable magnetic flux iron core column is one. The winding unit comprises a series winding (1), a common winding (5), a low-voltage winding (4), a tap winding (3) and an excitation winding (2); the excitation winding (2) and the series winding (1) are respectively wound on the same variable magnetic flux core column (8); the low-voltage winding (4), the tap winding (3) and the common winding (5) are respectively wound on the same constant magnetic flux core column (7); The series winding (1) is connected in series with the common winding (5), the excitation winding (2) is connected in series with the tap winding (3), and the series structure formed by the excitation winding (2) and the tap winding (3) is connected in parallel with the low-voltage winding (4).

6. The autotransformer body structure according to claim 5, characterized in that: The excitation winding (2) and the series winding (1) are wound on the variable flux core column in sequence from the inside to the outside.

7. The autotransformer body structure according to claim 6, characterized in that: The number of the constant flux core columns is identical, and the winding order of the low voltage winding, the tap winding and the common winding on each constant flux core column is the same. On each constant magnetic flux core column, each low voltage winding is connected in series in sequence; or, each low voltage winding is connected in parallel in sequence, and the number of turns of each low voltage winding is the same; or The tap windings are connected in series in sequence; or, the tap windings are connected in parallel in sequence, and the number of turns of the tap windings is the same; or The common windings are connected in series in sequence; or, the common windings are connected in parallel in sequence, and the number of turns of the common windings is the same.

8. The autotransformer body structure according to any one of claims 5 to 7, characterized in that: The series winding (1) adopts a parallel structure with a central incoming line and upper and lower outgoing lines; The common winding (5) adopts a parallel structure with a central incoming line and upper and lower outgoing lines.

9. The autotransformer body structure according to claim 8, characterized in that: The iron core adopts a four-column iron core, which includes two main columns, two side columns (6), an upper iron yoke and a lower iron yoke. The two main columns are respectively a constant magnetic flux iron core column (7) and a variable magnetic flux iron core column (8). The two side columns are respectively arranged on the outside of the two main columns, or The iron core adopts a five-column iron core, which includes three main columns, two side columns (6), an upper iron yoke and a lower iron yoke. The three main columns are respectively a variable magnetic flux iron core column (8) and two constant magnetic flux iron core columns (7). The two side columns are respectively arranged on the outside of the three main columns.

10. An autotransformer, characterized in that: The autotransformer comprises a body structure according to any one of claims 5 to 9.

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