CN216649234U

CN216649234U - Device for restraining forward and reverse transformation overvoltage of distribution transformer

Info

Publication number: CN216649234U
Application number: CN202122336640.8U
Authority: CN
Inventors: 何德强; 李晓芳
Original assignee: Honghe Power Supply Bureau of Yunnan Power Grid Co Ltd
Current assignee: Honghe Power Supply Bureau of Yunnan Power Grid Co Ltd
Priority date: 2021-09-26
Filing date: 2021-09-26
Publication date: 2022-05-31
Anticipated expiration: 2031-09-26

Abstract

The utility model relates to a device for inhibiting over-voltage of a distribution transformer in forward and reverse transformation, which comprises protective inductance coil devices arranged on the high-voltage side and the low-voltage side of the distribution transformer, wherein each inductance coil device comprises a silicon rubber insulating sleeve, a coil is arranged in the silicon rubber insulating sleeve, two ends of the coil are led out through a primary wiring board, the coil is wrapped by epoxy resin and is connected into a high-voltage side and a low-voltage side of the distribution transformer through the primary wiring board to enter and exit a current loop. After the thunder and lightning shock wave takes place, the shock wave through the inductance progressively increases, progressively grow, and the wave form of shock wave becomes gentle, and steepness, amplitude reduce respectively, effectively protect the transformer and indulge insulating.

Description

Device for restraining forward and reverse transformation overvoltage of distribution transformer

Technical Field

The utility model relates to the field of overvoltage protection of distribution transformers, in particular to a device for restraining forward and reverse transformation overvoltage of a distribution transformer.

Background

The distribution transformer is a static electric appliance with the voltage grade of 10-35 kV and the capacity of 6300KVA or below, which utilizes the electromagnetic induction principle to transform alternating voltage and current to transmit alternating current energy, is widely applied to power supply of urban and rural users, is installed in an open area of an electrical load center, and adopts zinc oxide arresters respectively arranged on high and low voltage sides as lightning protection measures.

However, the following problems exist in the operation process of the current distribution transformer:

1. the high voltage side of the distribution transformer is invaded by lightning waves, the lightning arrester acts, and the impact current flows through the grounding resistor to generate voltage

The low-voltage line is equivalent to wave impedance grounding, large impact current (same phase and same magnitude) flows through the low-voltage winding, and the magnetic flux generated in the iron core induces pulse potential with extremely high numerical value in the high-voltage winding according to the turn ratio of the transformer. For a high-voltage winding of the Y star connection wire, the high-voltage winding only has pulse potential and has no impact current, and the impact current in the low-voltage winding is completely changed into excitation current to generate great zero-sequence magnetic flux so that high potential is induced on the high-voltage side. Because the potential of the outlet end of the high-voltage winding is fixed by the residual voltage of the lightning arrester, the induced potential is distributed along the winding and has the maximum amplitude at a neutral point, and therefore, the neutral point is easy to break down in insulation. Meanwhile, the potential gradient between layers and between turns is correspondingly increased, and insulation breakdown between layers and between turns may occur at other positions.

2. When lightning waves are immersed into the distribution transformer from a low-voltage line, impact current flows through a low-voltage winding of the distribution transformer, and the impact current also generates induced electromotive force on a high-voltage winding according to the turn ratio, so that the potential of a neutral point on a high-voltage side is greatly improved, and the gradient voltage between layers and between turns is correspondingly increased.

3. When lightning invasion waves occur, breakdown discharge occurs due to the action of the high-voltage lightning arrester to form cut-off waves, the amplitude is close to 2 times of the invasion waves, and the wave head is steep and close to the right-angle wave head, so that a large voltage gradient is generated on a transformer winding, and longitudinal insulation of the transformer can be damaged.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems, the utility model provides a device for inhibiting the forward and reverse transformation overvoltage of a distribution transformer, which reduces the potential gradient between high-voltage winding layers and between turns caused by the forward and reverse transformation overvoltage respectively generated by distribution transformation low-voltage wave advance or high-voltage wave advance, and reduces the risk of insulation breakdown between the high-voltage winding layers and between turns; the risk of insulation breakdown of the neutral point of the high-voltage winding is reduced by reducing the gradient and the amplitude of the incoming wave.

The technical scheme of the utility model is as follows:

the device for inhibiting the forward and reverse transformation overvoltage of the distribution transformer comprises protective inductance coil devices arranged on the high-voltage side and the low-voltage side of the distribution transformer, wherein each inductance coil device comprises a silicon rubber insulating sleeve, a coil is arranged in each silicon rubber insulating sleeve, two ends of each inductance coil are led out through a primary wiring board, and each coil is wrapped by epoxy resin and is connected into a high-voltage side and a low-voltage side of the distribution transformer through the primary wiring board to enter and exit a current loop.

Further, the primary wiring board is arranged above or at two sides of the silicon rubber insulating sleeve.

Further, the inductor devices are provided in the A, B, C three phases on the high-voltage side and the a, b, and c three phases on the low-voltage side of the distribution transformer, respectively, and are mounted close to the surge arrester.

Furthermore, the coil comprises a coil body and folding parts which are respectively connected with the head and the tail of the coil body, one end of the front-end folding part is connected with the tail end of the first primary wiring board, the other end of the front-end folding part is connected with the head end of the coil body, one end of the rear-end folding part is connected with the tail end of the second primary wiring board, and the other end of the rear-end folding part is connected with the tail end of the coil body.

According to the utility model, by utilizing the principle that the current in the inductor can not change suddenly, firstly, the high-amplitude and high-gradient lightning waves are limited to directly act on the high-voltage winding of the distribution transformer, at the moment of lightning impulse wave invasion, the high-voltage side inductor coil of the distribution transformer is equivalent to an open circuit, a reflected voltage wave is formed at a 10kV lightning arrester, the voltage is increased to 2 times of the immersed wave, and the action reliability of the lightning arrester can be effectively improved; after the lightning arrester acts, the high-amplitude and high-gradient cut-off wave can not directly act on the high-voltage winding of the transformer due to the blocking effect of the inductor, and the potential gradient at the head end of the winding can be effectively reduced. After the thunder and lightning shock wave occurs, the shock wave passing through the inductance coil can only be gradually increased and gradually increased, the waveform of the shock wave becomes gentle, the gradient and the amplitude are respectively reduced, and the longitudinal insulation of the transformer can be effectively protected.

Compared with the prior art, the utility model has the following beneficial effects:

the overvoltage protection measures of the distribution transformer are perfected by installing the forward and reverse inverse transformation overvoltage devices on the distribution transformer, matching with the distribution transformer high-low side lightning arrester and the grounding device, suppressing the forward and reverse inverse transformation overvoltage, reducing the potential gradient between high-voltage winding layers and between turns caused by the overvoltage, reducing the risk of insulation breakdown between the high-voltage winding layers and between turns, and reducing the risk of insulation breakdown of a neutral point of the high-voltage winding by reducing the steepness and the amplitude of the wave advance; meanwhile, the method also has an inhibiting effect on high-voltage incoming waves caused by high-gradient and high-amplitude cut-off waves.

Drawings

FIG. 1 is a schematic diagram of the structure of the apparatus of the present invention;

FIG. 2 is a side view of the present invention;

fig. 3 is a schematic diagram of the arrangement of the present invention mounted on the high and low voltage sides of a distribution transformer.

Detailed Description

The technical solutions in the embodiments will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person skilled in the art based on the embodiments without making any creative efforts shall fall within the protection scope of the present application.

Unless otherwise defined, technical or scientific terms used in the embodiments of the present application should have the ordinary meaning as understood by those having ordinary skill in the art. The use of "first," "second," and similar terms in the present embodiments does not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. "mounted," "connected," and "coupled" are to be construed broadly and may, for example, be fixedly coupled, detachably coupled, or integrally coupled; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. "Upper," "lower," "left," "right," "lateral," "vertical," and the like are used solely in relation to the orientation of the components in the figures, and these directional terms are relative terms that are used for descriptive and clarity purposes and that can vary accordingly depending on the orientation in which the components in the figures are placed.

As shown in fig. 1 and 2, the inductance coil device 1 of the present embodiment includes a silicon rubber insulating sleeve 1.2, a coil 1.3 is disposed in the silicon rubber insulating sleeve 1.2, two ends of the coil are led out through a primary wiring board 1.1, the coil 1.3 is wrapped by epoxy resin 1.4, and the coil is connected to a current loop of the distribution transformer through the primary wiring board 1.1. The coil 1.3 is a copper coil. The main working part is a copper inductance coil, epoxy resin is a main insulating material, and high-temperature silicon rubber MVQ is an external insulating protective material and consists of corresponding matched connecting and fixing accessories.

As shown in fig. 3, in the present embodiment, the inductor device 1 is provided in A, B, C three phases on the high-voltage side and a, b, and c three phases on the low-voltage side of the distribution transformer, respectively, and is mounted close to the surge arrester.

Coil 1.3 includes the coil body, respectively with the coil body end to end's folding portion, front end folding portion one end and first wiring board end-to-end connection, the other end is connected with the coil body head end, rear end folding portion one end and the wiring board end-to-end connection of second, the other end and coil body end-to-end connection.

The working process of the embodiment is as follows:

because the corresponding inductance coil device 1 is also arranged on the low-voltage winding of the transformer, a large amount of lightning current flowing into the earth through the high-voltage side lightning arrester and the grounding device is limited by the low-voltage side inductance coil, the waveform and gradient of the shock wave appearing on the low-voltage side are improved, the amplitude and gradient of the overvoltage generated on the high-voltage winding by the inverse transformation overvoltage are limited, the deformation of the shock wave is smooth, and the effect of protecting the turn-to-turn insulation of the high-voltage side winding of the transformer is achieved.

Similarly, after the protective inductance coil device 1 is arranged on the low-voltage side of the distribution transformer, when lightning waves invade from the low-voltage side of the distribution transformer, the positive transformation overvoltage waveform, gradient and amplitude generated on the high-voltage winding are limited, and the effect of protecting the high-voltage winding of the distribution transformer is achieved.

In the embodiment, the forward and reverse conversion overvoltage devices of the distribution transformer are used as an important component in the main current loops of the inlet and outlet lines of the distribution transformer, the requirements of the distribution transformer on the installation environment are met, the forward and reverse conversion overvoltage devices are matched with the parameters of the protected transformer, and the manufacturing process and the technical performance of the forward and reverse conversion overvoltage devices meet the national standard requirements of GB 20840.1-2010, GB 20840.2-2014 and the like. The overvoltage protection measure of the distribution transformer is formed by the distribution transformer applied to the area with frequent thunder and lightning activities, the lightning arrester and the grounding device, and is supplementary and perfect to the overvoltage protection measure of the distribution transformer. When the lightning arrester is installed, the lightning arrester is required to be installed close to the lightning arrester as much as possible, and the lightning arrester is firmly fixed.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. An apparatus for suppressing forward and reverse switching overvoltages of a distribution transformer, comprising: the high-voltage side and low-voltage side protection inductance coil device comprises a silicon rubber insulation sleeve, wherein a coil is arranged in the silicon rubber insulation sleeve, two ends of the coil are led out through a primary wiring board, the coil is wrapped by epoxy resin and is connected into a high-voltage side and a low-voltage side of a distribution transformer through the primary wiring board to enter and exit a current loop.

2. The apparatus of claim 1, wherein the means for suppressing forward and reverse switching overvoltages of the distribution transformer comprises: the primary wiring board is arranged above or at two sides of the silicon rubber insulating sleeve.

3. The apparatus of claim 1, wherein the means for suppressing forward and reverse switching overvoltages of the distribution transformer comprises: the inductance coil devices are respectively provided on the A, B, C three phases on the high-voltage side and the a, b, and c three phases on the low-voltage side of the distribution transformer, and are mounted close to the surge arrester.

4. The apparatus for suppressing forward and reverse switching overvoltage of a distribution transformer according to claim 1, wherein: the coil comprises a coil body and folding parts which are respectively connected with the head and the tail of the coil body, wherein one end of the front-end folding part is connected with the tail end of a first primary wiring board, the other end of the front-end folding part is connected with the head end of the coil body, one end of the rear-end folding part is connected with the tail end of a second primary wiring board, and the other end of the rear-end folding part is connected with the tail end of the coil body.