WO2023197635A1 - Entire-medium-voltage two-stage voltage transformer - Google Patents

Abstract

An entire-medium-voltage two-stage voltage transformer (400), comprising: a first-stage iron core (401) and a second-stage iron core (402) connected in parallel. A first primary winding (403) is a primary excitation winding, a first secondary winding (405) is a secondary power supply winding, and the first primary winding (403) and the first secondary winding (405) are wound on the first-stage iron core (401) to form a first-stage voltage transformer; a second primary winding (404) and a second secondary winding (407) are proportional windings and are wound on the first-stage iron core (401) and the second-stage iron core (402), and the second primary winding (404), the second secondary winding (407) and the second-stage iron core (402) form a second-stage voltage transformer; a high-voltage end of the first primary winding (403) is connected to a high-voltage end of the second primary winding (404), and a low-voltage end of the first primary winding (403) is connected to a low-voltage end of the second primary winding (404); a first single-turn auxiliary winding (406) is wound on the first-stage iron core (401); a second single-turn auxiliary winding (408) is wound on the second-stage iron core (402); the first primary winding (403) and the second primary winding (404) have the same structure, and each comprises a first winding unit, a second winding unit, a third winding unit and a fourth winding unit.

Description

A full medium voltage two-stage voltage transformer

Cross-references to related applications

This disclosure is based on a Chinese patent application with the application number 202210414559.3, the filing date being April 15, 2022, and the application name being “a full medium voltage dual-stage voltage transformer”, and claims the priority of the Chinese patent application. The entire contents of the Chinese patent application are hereby incorporated by reference into this disclosure.

Technical field

The present disclosure relates to the technical field of high-voltage testing, and mainly relates to a full medium-voltage two-stage voltage transformer.

Background technique

The power frequency voltage ratio standard is a measurement tool or method used to reproduce the power frequency voltage ratio, which needs to meet two conditions: stability and traceability. With the rapid development of the world's electric power industry in the past two centuries, the research and application of power frequency voltage ratio standards have also experienced a long development process. At present, the power frequency voltage ratio standards commonly used in the world mainly include resistive, capacitive and electromagnetic types.

Resistive and capacitive standard devices are greatly affected by temperature, and their stability is not as good as electromagnetic standard devices. The electromagnetic power frequency voltage proportional standard has the advantages of simple principle, easy use, stability and reliability. Among the electromagnetic structures, the two-stage standard transformer has high accuracy and good stability, and is also the most widely used.

Double-stage voltage transformer is a special structure voltage transformer composed of two-stage voltage transformers. The principle circuit is shown in Figure 1. In Figure 1, N _1e is the primary excitation winding, N _2e is the secondary power supply winding, N _1e and N _2e are wound on the first-level iron core C1 to form the first-level voltage transformer, which is equivalent to a general single-level voltage transformer. , let its error be ε ₁ . N ₁ and N ₂ are proportional windings, wound on the first-level iron core C1 and the second-level iron core C2. N ₁ , N ₂ and iron core C2 constitute the second stage voltage transformer, and its error is assumed to be ε ₂ . In this way, N _1e , N _2e , N ₁ , N ₂ and iron cores C1 and C2 form a two-stage voltage transformer, and its error is assumed to be ε. Where N _1e and N ₁ turns are equal. Its equivalent circuit is shown in Figure 2. In Figure 2, Z′ ₂ and U′ ₂ are the secondary impedance and secondary induced voltage converted to the primary side respectively.

Defined by the transformer error, there are:

In the formula, I ₀₁ is the excitation current of the first-level transformer; I ₀₂ is the excitation current of the second-level transformer; Z _m1 is the excitation impedance of the first-level transformer; Z _m2 is the excitation impedance of the second-level transformer. ; Z _1e is the internal impedance of the primary winding N _1e of the first-stage transformer; Z ₁ is the internal impedance of the primary winding N ₁ of the second-stage transformer; U ₁ is the primary voltage of the double-stage voltage transformer; U′ ₂ is the double-stage The voltage transformer converts the secondary voltage to the primary side.

It can be seen that the no-load error of a two-stage voltage transformer is the negative value of the product of the no-load error of the first stage and the second stage. If the error of the first-stage transformer is 0.1% ~ 0.01%, and the internal impedance of the second-stage transformer is equivalent to the first stage, but due to the decrease in excitation impedance, the error is 1% ~ 0.1%, then the double-stage voltage transformer The error can reach 10 ^-5 ~ 10 ^-7 , and it can be used as a high-accuracy power frequency voltage ratio standard instrument.

However, since the first-stage winding must pass through the second-stage winding, the insulation between the windings is difficult to design, and generally the maximum can only be 10kV. In order to develop a two-stage voltage transformer with a higher voltage level, a new iron core winding arrangement structure is provided in the related technology. As shown in Figure 3, different from the traditional two-stage voltage transformer, the excitation winding N ₁ and the proportional winding N ₂ N ₃ are separated at both ends of the rectangular core C1, and do not adopt the form of internal and external winding. The second-stage iron core C2 is placed on the N ₂ N ₃ side of the proportional winding. This design avoids the insulation and capacitive leakage problems caused by the proportional winding and the inner and outer windings of the excitation winding in the low-voltage double-stage transformer. However, at this time, there is also the problem that the two-stage transformer cannot cover all transformer ratios required for the entire medium voltage range.

Contents of the invention

The present disclosure proposes a full medium voltage two-stage voltage transformer to solve the problem of how to realize a voltage transformer that can cover all transformer ratios required for the entire medium voltage range.

In order to solve the above problems, according to one aspect of the present disclosure, a full medium-voltage two-stage voltage transformer is provided. The voltage transformer includes: a first-level iron core, a second-level iron core, a first primary winding, a third-level iron core, and a first-level iron core. two primary windings, a first secondary winding, a first single-turn auxiliary winding, a second secondary winding and a second single-turn auxiliary winding;

Wherein, the first-level iron core and the second-level iron core are connected in parallel; the first primary winding is a primary excitation winding, the first secondary winding is a secondary power supply winding, and the first primary winding and the first The secondary winding is wound on the first-level iron core to form a first-level voltage transformer; the second primary winding and the second secondary winding are proportional windings, wound on the first-level iron core and the second-level iron core. , the second primary winding, the second secondary winding and the second iron core constitute a second-level voltage transformer; the high-voltage end of the first primary winding is connected to the high-voltage end of the second primary winding, and the The low-voltage end of the first primary winding is connected to the low-voltage end of the second primary winding; the first single-turn auxiliary winding is wound on the first-stage iron core; the second single-turn auxiliary winding is wound on the On the second iron core;

The first primary winding and the second primary winding have the same structure, and both include a first winding unit, a second winding unit, a third winding unit and a fourth winding unit.

In some embodiments, the first primary winding and the second primary winding are used to achieve a transformation ratio of 5 kV to 40 kV to 100 V.

In some embodiments, each winding unit has a rated voltage of 10 kV.

In some embodiments, when the first primary winding or the second primary winding is in the working mode of 40kV, the first winding unit, the second winding unit, the third winding unit and the fourth electrical winding unit are connected in series in sequence connected, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, when the first primary winding or the second primary winding is in the 20kV operating mode, the parallel structure of the first winding unit and the second winding unit is combined with the third winding unit and the fourth winding unit. The structure after the units are connected in parallel is connected in series, the high-voltage end of the first winding unit is connected to the high-voltage end of the second winding unit, and the low-voltage end of the first winding unit is connected to the low-voltage end of the second winding unit. The high-voltage end of the third winding unit is connected to the high-voltage end of the fourth winding unit, the low-voltage end of the third winding unit is connected to the low-voltage end of the fourth winding unit, and the first winding unit The low-voltage end of the fourth winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, when the first primary winding or the second primary winding is in an operating mode of 10 kV, the first winding unit, the second winding unit, the third winding unit and the fourth electrical winding unit In parallel connection, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, the second secondary winding is five windings with 63 to 126 turns to achieve multiple voltage transformation ratios.

The present disclosure provides a full medium-voltage two-stage voltage transformer, including: a first-level iron core, a second-level iron core, a first primary winding, a second primary winding, a first secondary winding, and a first single-turn auxiliary winding. winding, a second secondary winding and a second single-turn auxiliary winding; the first primary winding and the second primary winding have the same structure, and both include a first winding unit, a second winding unit, a third winding unit and a fourth winding unit. This disclosure divides the primary winding into 4 sections and designs multiple working modes to make the magnetic working point of the transformer core constant without excessively low magnetic density or magnetic saturation. The secondary winding is designed with multiple different turns numbers to match the primary A variety of different series and parallel modes of windings form a variety of different transformation ratios, which can cover all transformer ratios required in the entire medium voltage range. The voltage transformers of the present disclosure all have strong load capacity. The first stage The load error is less than 20ppm, and the second-stage proportional winding is less than 0.5ppm.

Description of the drawings

Exemplary embodiments of the present disclosure may be more fully understood by reference to the following drawings:

Figure 1 is the principle circuit diagram of a two-stage voltage transformer;

Figure 2 is the equivalent circuit diagram of a two-stage voltage transformer;

Figure 3 is a structural diagram of a high-voltage two-stage voltage transformer;

Figure 4 is a schematic structural diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure;

Figure 5 is a schematic diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure;

Figure 6A is a connection diagram of the primary winding in an operating mode of 40kV according to an embodiment of the present disclosure;

Figure 6B is a connection diagram of the primary winding in an operating mode of 20kV according to an embodiment of the present disclosure;

Figure 6C is a connection diagram of the primary winding in an operating mode of 10kV according to an embodiment of the present disclosure;

Figure 7 is a schematic diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure.

Detailed ways

Exemplary embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete. disclosure, and fully convey the scope of the present disclosure to those skilled in the art. The terminology used in the exemplary embodiments represented in the drawings does not limit the present disclosure. In the drawings, identical units/elements use the same reference numerals.

Unless otherwise defined, the terms (including scientific and technical terms) used herein have the commonly understood meaning to one of ordinary skill in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have consistent meanings in the context of their relevant fields and should not be understood as having an idealized or overly formal meaning.

Usually, the voltage transformer can only be applied to a certain fixed rated voltage Un, and the working range is (20% ~ 120%) Un. If it is lower than this range, the operating magnetic density is too low and the error increases; if it is higher than this range, the magnetic density is saturated and the transformer cannot work properly. Therefore, in the medium voltage range (1kV-35kV), several voltage transformers of different voltage levels are generally required, such as 1kV, 2kV, 3kV, 5kV, 6kV, 10kV, 20kV, 35kV, etc.

The present invention discloses a design scheme of a two-stage voltage transformer with a rated maximum voltage of 40kV and a rated minimum voltage of 1kV.

Figure 4 is a schematic structural diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure. As shown in Figure 4, the full medium-voltage two-stage voltage transformer provided by the embodiment of the present disclosure divides the primary winding into four sections and designs multiple working modes to make the magnetic operating point of the transformer core constant and no magnetic field will occur. Density is too low or magnetic saturation; the secondary winding is designed with a variety of different turns, combined with a variety of different series and parallel modes of the primary winding, to form a variety of different transformation ratios, which can cover all transformer ratios required in the entire medium voltage range , the voltage transformers provided by the embodiments of the present disclosure all have strong load capacity, the first-stage load error is less than 20ppm, and the second-stage proportional winding is less than 0.5ppm. The full medium-voltage two-stage voltage transformer 400 provided by the embodiment of the present disclosure includes: a first-stage iron core 401, a second-stage iron core 402, a first primary winding 403, a second primary winding 404, and a first secondary winding 405. , the first single-turn auxiliary winding 406, the second secondary winding 407 and the second single-turn auxiliary winding 408.

Wherein, the first-level iron core and the second-level iron core are connected in parallel; the first primary winding is a primary excitation winding, the first secondary winding is a secondary power supply winding, and the first primary winding and the first The secondary winding is wound on the first-level iron core to form a first-level voltage transformer; the second primary winding and the second secondary winding are proportional windings, wound on the first-level iron core and the second-level iron core. , the second primary winding, the second secondary winding and the second iron core constitute a second-level voltage transformer; the high-voltage end of the first primary winding is connected to the high-voltage end of the second primary winding, and the The low-voltage end of the first primary winding is connected to the low-voltage end of the second primary winding; the first single-turn auxiliary winding is wound on the first-stage iron core; the second single-turn auxiliary winding is wound on the On the second core, the first primary winding and the second primary winding have the same structure, and both include a first winding unit, a second winding unit, a third winding unit and a fourth winding unit.

In some embodiments, the first secondary winding and the second secondary winding have the same number of turns.

Figure 4 is a schematic diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure. As shown in Figure 4, the voltage transformer consists of two levels of iron cores, the first level iron core C1 and the high magnetic permeability second level iron core C2. The first primary winding W _P,I is designed to have a voltage of 120% of the highest rated value at the maximum test point (40kV), rated frequency (50Hz). Several first secondary windings W _S,I and a first single-turn auxiliary winding AuxI are used as secondary. The first secondary winding W _S,I is used to power the error calibration device or to excite the cascaded inductive voltage divider. Ideally, the magnetic error of the first stage transformer is 10 ^-4 or less.

The second primary winding WP _,II has the same structure as the first primary winding _WP,I, and the second secondary winding _WS,II has the same number of turns as the first secondary winding _WS,I . The second single-turn auxiliary winding AuxII is a single-turn winding specially wound on the second-stage iron core C2. It is used to measure the magnetization intensity in the second-stage iron core C2 (actually the magnetization error voltage of the first-stage iron core C1). Ideally, the magnetic error of the second-stage core is 10 ^-3 or less.

In some embodiments, the first primary winding and the second primary winding are used to achieve a transformation ratio of 5 kV to 40 kV to 100 V.

In some embodiments, each winding unit has a rated voltage of 10 kV.

In some embodiments, when the first primary winding or the second primary winding is in the working mode of 40kV, the first winding unit, the second winding unit, the third winding unit and the fourth electrical winding unit are connected in series in sequence connected, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, when the first primary winding or the second primary winding is in the 20kV operating mode, the parallel structure of the first winding unit and the second winding unit is combined with the third winding unit and the fourth winding unit. The structure after the units are connected in parallel is connected in series, the high-voltage end of the first winding unit is connected to the high-voltage end of the second winding unit, and the low-voltage end of the first winding unit is connected to the low-voltage end of the second winding unit. The high-voltage end of the third winding unit is connected to the high-voltage end of the fourth winding unit, the low-voltage end of the third winding unit is connected to the low-voltage end of the fourth winding unit, and the first winding unit The low-voltage end of the fourth winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, when the first primary winding or the second primary winding is in an operating mode of 10 kV, the first winding unit, the second winding unit, the third winding unit and the fourth electrical winding unit In parallel connection, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.

In some embodiments, the second secondary winding is five windings with 63 to 126 turns to achieve multiple voltage transformation ratios.

Continuing to take FIG. 5 as an example, in the embodiment of the present disclosure, in order to achieve the required minimum and maximum voltage ratios of 5kV/100V and 40kV/100V, the first primary winding W _P,I and the second primary winding W _{P ,II} is divided into 4 winding units.

Taking the first primary winding as an example, it is divided into a first winding unit W _P,I (A), a second winding unit W _P,I (B), a third winding unit W _P,I (C) and a fourth winding unit. W _{P, I} (D) have four winding units in total, and different working modes can be achieved through different series and parallel connections.

In some embodiments, as shown in Figure 6A, when the first primary winding is in the 40kV operating mode, _WP,I (A), _WP,I (B), _WP,I (C ) and W _P,I (D) are connected in series in turn. The low-voltage end of W _P,I (A) serves as the low-voltage end of the first primary winding, and the high-voltage end of W _P,I (D) serves as the high-voltage end of the first primary winding. .

In some embodiments, as shown in Figure 6B, when the first primary winding WP _,I is in the 20kV operating mode, _WP,I (A) and _WP,I (B) are connected in parallel. The structure is connected in series with the parallel structure of W _P,I (C) and W _P,I (D). The high-voltage end of W _P,I (A) is connected to the high-voltage end of W _P,I (B). W _{P ,The low-voltage end of I} (A) is connected to the low-voltage end of W _P,I (B), the high-voltage end of W _P,I (C) is connected to the high-voltage end of W _P,I (D), W _P,I The low-voltage end of (C) is connected to the low-voltage end of W _P,I (D), the low-voltage end of W _P,I (A) serves as the low-voltage end of the first primary winding, and the high-voltage end of W _P,I (D) serves as The high voltage side of the first primary winding.

In some embodiments, as shown in Figure 6C, when the first primary winding WP _,I is in the 10kV operating mode, _WP,I (A), _WP,I (B), _{WP ,I} (C) and WP _,I (D) are connected in parallel, the low-voltage end of WP _,I (A) is used as the low-voltage end of the first primary winding, and the high-voltage end of _WP,I (D) is used as the first primary winding. high voltage end.

During use, the structure of the second primary winding WP _,II is the same as the structure of the first primary winding _WP,I . Please refer to the above embodiments.

Figure 7 is a schematic diagram of a full medium voltage two-stage voltage transformer according to an embodiment of the present disclosure. As shown in Figure 7, the four coils at the top form the first primary winding WP _,I , and the four coils at the bottom form the second primary winding _WP,II . Each coil is a winding unit W(n) , the first primary winding and the first secondary winding are wound on the first-level iron core C1; the second primary winding and the second secondary winding are proportional windings, wound on the first-level iron core C1 and the second-level iron core C2 superior.

In the embodiment of the present disclosure, in order to develop a full medium voltage two-stage voltage transformer suitable for 5kV ~ 40kV, the design is as follows. Table 1 shows the rated conditions and transformation ratios in three different modes. The maximum voltage should be 1.2Upn. To estimate the required number of turns, the calculated number of turns is shown in Table 2. When 100% excitation is set, the voltage of each winding turn is 1.6V, the maximum induction is 1.5T (peak), and the maximum is 48kV. Therefore, based on the primary turns number of 25200 turns (4x6300 turns), only 5 secondary windings (63, 72, 84, 105, 126) of 63 turns to 126 turns can achieve 15 different voltage ratios.

Next, further calculate the load error of the transformer. The calculation process is as follows:

First, the first stage transformer. The thickness of the primary wire is 0.3 mm), the primary resistance (series connection) of 40kV series mode is about 2.2kΩ, and after converting to the secondary, the primary resistance is only 0.22Ω (in the smallest case (5kV/100V)). The secondary winding uses a medium wire thickness of 1.4 mm in diameter (about 1.5 square millimeters), and 126 turns can achieve a maximum resistance of 0.5Ω. This will result in a total maximum output resistance of 0.72Ω. If the load impedance is 100kΩ, the load error is 0.72/100k=7.2ppm. Generally it can be less than 20ppm.

Next, calculate the second-level transformer. The wiring resistance of the primary should ideally be designed to be less than 0.5 ohms (referred to the secondary with the lowest turns ratio). The wiring resistance of even this lowest turns ratio secondary should be less than 0.5Ω. This ensures that when the load is an inductive voltage divider, the capacitive load of its second-stage winding (less than 2nF, approximately 2MΩ at 50Hz) is less than 0.5ppm (2Ω/2MΩ).

Table 1 Rated voltage, transformation ratio and number of turns of transformer

Table 2 Estimated number of turns of the first-stage iron core

B max	1.5	T
U pn,rms	40000	V
U p /N p (@100%)	1.6	V/Wdg.
f	50	Hz
k	0.95	​
A core	61	cm 2
min(N p )	25000	​
μ r	40000	​

The disadvantage of switching between 3 modes is that the ratio and phase errors will be different in different modes, although the operating point of the core is the same. The reason is that the stray magnetic field and internal winding capacitance are different in different modes. Nonetheless, the ratio and phase errors are expected to be constant over a wide operating range, as low as 1% of the highest rated voltage in certain modes, i.e. VT should be possible from 1kV (lowest test voltage, 20% of 5kV) to 48kV (Maximum test voltage). Since this transformer is a two-stage transformer, it has the advantage of ultra-precision and can cover all transformer ratios required in the entire medium voltage range.

The present disclosure has been described with reference to a few embodiments. However, it will be known to those skilled in the art that other embodiments than those disclosed above are equally within the scope of the present disclosure, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless otherwise expressly defined therein. All references to "a/the/the [means, component, etc.]" are to be construed openly to mean at least one instance of the said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein are not necessarily performed in the exact order disclosed unless explicitly stated.

Those skilled in the art will understand that embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment that combines software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure but not to limit it. Although the present disclosure has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present disclosure can still be modified. Modifications or equivalent substitutions may be made to the specific implementations, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the present disclosure shall be covered by the scope of protection of the claims of the present disclosure.

Industrial applicability

The present disclosure provides a full medium-voltage two-stage voltage transformer, including: a first-stage iron core and a second-stage iron core connected in parallel; the first primary winding is a primary excitation winding, and the first secondary winding is a secondary power supply winding. The first primary winding and the first secondary winding are wound on the first-level iron core to form the first-level voltage transformer; the second primary winding and the second secondary winding are proportional windings, wound on the first-level iron core and the second-level voltage transformer. On the secondary iron core, the second primary winding, the second secondary winding and the second iron core form a second-level voltage transformer; the high-voltage end of the first primary winding is connected to the high-voltage end of the second primary winding, and the first primary winding The low-voltage end of the winding is connected to the low-voltage end of the second primary winding; the first single-turn auxiliary winding is wound on the first-stage iron core; the second single-turn auxiliary winding is wound on the second iron core; the first primary winding and the The two primary windings have the same structure, and both include a first winding unit, a second winding unit, a third winding unit and a fourth winding unit. This disclosure divides the primary winding into 4 sections and designs multiple working modes to make the magnetic working point of the transformer core constant without excessively low magnetic density or magnetic saturation. The secondary winding is designed with multiple different turns numbers to match the primary A variety of different series and parallel modes of windings form a variety of different transformation ratios, which can cover all transformer ratios required in the entire medium voltage range. The voltage transformers of the present disclosure all have strong load capacity. The first stage The load error is less than 20ppm, and the second-stage proportional winding is less than 0.5ppm.

Claims (7)

1. A full medium voltage two-stage voltage transformer, wherein the voltage transformer includes: a first-level iron core, a second-level iron core, a first primary winding, a second primary winding, a first secondary winding, a first Single-turn auxiliary winding, second secondary winding and second single-turn auxiliary winding;

   Wherein, the first-level iron core and the second-level iron core are connected in parallel; the first primary winding is a primary excitation winding, the first secondary winding is a secondary power supply winding, and the first primary winding and the first The secondary winding is wound on the first-level iron core to form a first-level voltage transformer; the second primary winding and the second secondary winding are proportional windings, wound on the first-level iron core and the second-level iron core. , the second primary winding, the second secondary winding and the second iron core constitute a second-level voltage transformer; the high-voltage end of the first primary winding is connected to the high-voltage end of the second primary winding, and the The low-voltage end of the first primary winding is connected to the low-voltage end of the second primary winding; the first single-turn auxiliary winding is wound on the first-stage iron core; the second single-turn auxiliary winding is wound on the On the second iron core;

   The first primary winding and the second primary winding have the same structure, and both include a first winding unit, a second winding unit, a third winding unit and a fourth winding unit.
2. According to the voltage transformer of claim 1, the first primary winding and the second primary winding are used to achieve a transformation ratio of 5kV to 40kV to 100V.
3. According to the voltage transformer of claim 2, the rated voltage of each winding unit is 10kV.
4. The voltage transformer according to claim 2, when the first primary winding or the second primary winding is in the working mode of 40kV, the first winding unit, the second winding unit, the third winding unit and the fourth winding unit The winding units are connected in series in sequence, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding. end.
5. The voltage transformer according to claim 2, when the first primary winding or the second primary winding is in the working mode of 20kV, the parallel structure of the first winding unit and the second winding unit and the third winding unit The structure connected in parallel with the fourth winding unit is connected in series. The high voltage end of the first winding unit is connected to the high voltage end of the second winding unit. The low voltage end of the first winding unit is connected to the low voltage end of the second winding unit. terminals are connected, the high-voltage terminal of the third winding unit is connected to the high-voltage terminal of the fourth winding unit, the low-voltage terminal of the third winding unit is connected to the low-voltage terminal of the fourth winding unit, the The low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the high-voltage end of the first primary winding or the second primary winding.
6. The voltage transformer according to claim 2, when the first primary winding or the second primary winding is in the 10kV working mode, the first winding unit, the second winding unit, the third winding unit and the third winding unit Four electrical winding units are connected in parallel, the low-voltage end of the first winding unit serves as the low-voltage end of the first primary winding or the second primary winding, and the high-voltage end of the fourth winding unit serves as the first primary winding or the second primary winding. high voltage side.
7. According to the voltage transformer of claim 1, the second secondary winding is five windings with 63 to 126 turns.

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