Anti-direct-current low-voltage voltage transformer

Abstract

The invention discloses an anti-direct-current low-voltage voltage transformer, and belongs to the technical field of electrical measurement. The notch iron core, the primary winding, the secondary winding and the anti-direct-current assembly are arranged in the shell. The secondary winding and the primary winding are sequentially wound on the notch iron core; wiring terminals are arranged at the top of the shell and are respectively connected with the secondary winding and the primary winding; the anti-DC assembly comprises a current-limiting resistor and an over-current protection resistor, and the current-limiting resistor and the over-current protection resistor are connected in parallel and are connected in series with the primary winding. The structure is compact, and there is no exposed component except the wiring terminal; and direct current in the primary winding can be limited under the working condition containing the direct current component, iron core saturation is avoided, and the primary winding is prevented from being heated and burnt.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical measurement, and in particular relates to a DC-resistant low-voltage voltage transformer. Background Art

[0002] Electromagnetic voltage transformers work based on the principle of electromagnetic induction. Their main function is to accurately convert a primary high voltage into a low voltage that can be measured by instruments and equipment. They have the advantages of simple and reliable structure and high accuracy at power frequency. They are widely used in voltage measurement, monitoring, protection and other scenarios. With the implementation of various new energy projects, voltage transformers, as an important part of system operation monitoring, have also appeared in various photovoltaic container substations.

[0003] The International Energy Agency (IEA) recently released the 2024 Renewable Energy Report, which states that in the next decade, solar photovoltaics will become the core force driving the rapid development of global renewable energy. Based on the existing renewable energy policies, it is expected that the installed capacity of ground photovoltaic power stations and distributed photovoltaics will almost double in the next few years. By 2030, the capacity of ground photovoltaics will increase from the current 917.1GW to 3467.1GW, and distributed photovoltaics will also increase from the current 694.4GW to 2353.5GW. The continuous advancement of technology has also led to the continuous improvement of the efficiency of photovoltaic modules and the continuous reduction of costs. In the next few years, photovoltaic projects will continue to maintain a relatively high growth rate, and the market prospects for the corresponding voltage transformers are broad.

[0004] However, new energy and energy storage projects are different from conventional factory projects. The electricity they generate has characteristics such as high DC component, large harmonic content, and high-power operation in a short period of time. These are severe tests for the reliability of equipment in the line link. Due to the limitation of the principle, the operating frequency of the electromagnetic voltage transformer is limited to a very small range (generally 50Hz), and it is extremely sensitive to the DC component in the primary system voltage. A DC component of about 1% can cause the transformer core to saturate, and then cause the primary winding to heat up, which will cause the transformer to burn out over time. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a DC-resistant low-voltage voltage transformer to solve the problem that the electromagnetic voltage transformer cannot operate stably under conditions containing a DC component.

[0006] The present invention provides the following technical solutions: A DC-resistant low-voltage voltage transformer comprises a shell and a cut-out iron core, a primary winding, a secondary winding and a DC-resistant component arranged in the shell; the secondary winding and the primary winding are wound on the cut-out iron core in sequence; a connection terminal is provided on the top of the shell, which is respectively connected to the secondary winding and the primary winding; the DC-resistant component comprises a current limiting resistor and an overcurrent protection resistor, the current limiting resistor and the overcurrent protection resistor are connected in parallel, and are connected in series with the primary winding.

[0007] As an optional technical solution of the present invention, the cut core includes a first cut core and a second cut core; the first cut core and the second cut core are arranged side by side and are connected through a coil frame; the secondary winding and the primary winding are wound on the coil frame in sequence.

[0008] As an optional technical solution of the present invention, both the first cut core and the second cut core are provided with an air gap for adjusting the magnetic density of the first cut core or the second cut core.

[0009] As an optional technical solution of the present invention, the overcurrent protection resistor is arranged outside the primary winding.

[0010] As an optional technical solution of the present invention, the primary winding is wound on the outside of the secondary winding.

[0011] As an optional technical solution of the present invention, the shell includes a shell cover and a shell body; the shell cover is arranged on the top of the shell body, and the connection terminal is arranged above the shell cover; insulating resin is poured in the shell body.

[0012] As an optional technical solution of the present invention, the wiring terminals include a first wiring terminal A, a first wiring terminal B, a second wiring terminal a and a second wiring terminal b; the first wiring terminal A is connected to the primary winding, and the first wiring terminal B is connected to the DC protection component; the second wiring terminal a and the second wiring terminal b are both connected to the secondary winding.

[0013] As an optional technical solution of the present invention, the overcurrent protection resistor adopts a PTC thermistor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The DC-resistant low-voltage voltage transformer provided by the present invention can limit the DC current in the primary winding under the working condition containing DC components through the DC-resistant component, avoid core saturation, and prevent the primary winding from heating and burning; the structure is compact, and there are no exposed components except the wiring terminals, thus avoiding possible damage due to bumps during transportation and installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view of a DC-resistant low-voltage voltage transformer according to an embodiment of the present invention; Figure 2 Schematic diagram of the structure of the notched core, the primary winding and the secondary winding in an embodiment of the present invention; Figure 3 is a schematic structural diagram of a DC-resistant low-voltage voltage transformer in an embodiment of the present invention; Figure 4 Schematic diagram of the connection of the wiring terminals in the embodiment of the present invention.

[0016] The markings in the figure are: 1. Shell cover; 2. Shell body; 3. First cut core; 4. Second cut core; 5. Coil skeleton; 6. Primary winding; 7. Secondary winding; 8. Current limiting resistor; 9. Overcurrent protection resistor; 10. Insulating resin; 11. First terminal A; 12. First terminal B; 13. Second terminal a; 14. Second terminal b. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0018] Example 1 This embodiment provides a DC-resistant low-voltage voltage transformer, such as Figure 1 As shown, it includes a shell, a cut-out core arranged in the shell, a primary winding 6, a secondary winding 7 and a DC protection component.

[0019] The secondary winding 7 and the primary winding 6 are wound on the cut-out core in sequence; the top of the shell is provided with connection terminals, which are connected to the secondary winding 7 and the primary winding 6 respectively.

[0020] The DC protection component includes a current limiting resistor 8 and an overcurrent protection resistor 9 . The current limiting resistor 8 and the overcurrent protection resistor 9 are connected in parallel and in series with the primary winding 6 .

[0021] In this embodiment, when the primary side system of the voltage transformer operates normally and the voltage of the primary winding 6 is a normal power frequency signal, the current of the primary winding 6 is low, the overcurrent protection resistor 9 does not work and is in a low resistance state, the current limiting resistor 8 is short-circuited, and the DC resistance component is in a low resistance state as a whole, which does not affect the measurement accuracy of the voltage transformer. When a DC component appears in the primary side system of the voltage transformer and causes the cut core to operate in a saturated state, the current of the primary winding 6 begins to increase until it reaches the working current of the overcurrent protection resistor 9. At this time, the overcurrent protection resistor 9 is close to an open circuit, and the DC resistance component is in a high resistance state as a whole. The current of the primary winding 6 is reduced until the DC component in the system disappears and the DC resistance component returns to a low resistance state.

[0022] Example 2 like Figure 1-4As shown, in this embodiment, based on the embodiment 1, the cut core includes a first cut core 3 and a second cut core 4. The first cut core 3 and the second cut core 4 are arranged side by side and connected with a coil frame 5. The secondary winding 7 and the primary winding 6 are wound on the coil frame 5 in sequence.

[0023] Furthermore, the first cutout core 3 and the second cutout core 4 pass through the hole in the center of the coil frame 5 and are combined to form a Japanese-shaped structure.

[0024] Furthermore, the first cut core 3 and the second cut core 4 are both provided with an air gap for adjusting the magnetic density of the first cut core 3 or the second cut core 4 .

[0025] Furthermore, the primary winding 6 is wound on the outside of the secondary winding 7 .

[0026] The housing comprises a housing upper cover 1 and a housing body 2 ; the housing upper cover 1 is arranged on the top of the housing body 2 , and the connection terminal is arranged above the housing upper cover 1 ; and insulating resin 10 is poured in the housing body 2 .

[0027] The wiring terminals include a first wiring terminal A11, a first wiring terminal B12, a second wiring terminal a13, and a second wiring terminal b14; the first wiring terminal A11 is connected to the primary winding 6, and the wire is connected to the DC protection component after the specified number of turns on the primary winding 6, and the first wiring terminal B12 is connected to the DC protection component. The second wiring terminal a13 and the second wiring terminal b14 are both connected to the secondary winding 7. The second wiring terminal a13 is connected to the secondary winding 7, and the wire is led out and connected to the second wiring terminal b14 after the specified number of turns on the secondary winding 7.

[0028] The overcurrent protection resistor 9 is arranged outside the primary winding 6. The overcurrent protection resistor 9 is a PTC thermistor.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A DC-resistant low-voltage voltage transformer, characterized in that: It comprises a shell, a cut-out iron core arranged in the shell, a primary winding (6), a secondary winding (7) and a DC protection component; The secondary winding (7) and the primary winding (6) are sequentially wound on the cut-out iron core; the top of the housing is provided with connection terminals, which are respectively connected to the secondary winding (7) and the primary winding (6); The DC-resistant component comprises a current-limiting resistor (8) and an overcurrent protection resistor (9); the current-limiting resistor (8) and the overcurrent protection resistor (9) are connected in parallel and in series with the primary winding (6).

2. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The notched iron core comprises a first notched iron core (3) and a second notched iron core (4); The first cutout iron core (3) and the second cutout iron core (4) are arranged side by side and are penetrated and connected with a coil frame (5); The secondary winding (7) and the primary winding (6) are sequentially wound on the coil frame (5).

3. The DC-resistant low-voltage voltage transformer according to claim 2, characterized in that: The first notched iron core (3) and the second notched iron core (4) are both provided with an air gap for adjusting the magnetic density of the first notched iron core (3) or the second notched iron core (4).

4. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The overcurrent protection resistor (9) is arranged outside the primary winding (6).

5. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The primary winding (6) is wound on the outside of the secondary winding (7).

6. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The housing comprises a housing upper cover (1) and a housing body (2); The housing upper cover (1) is arranged on the top of the housing body (2), and the connection terminals are arranged above the housing upper cover (1); and insulating resin (10) is poured into the housing body (2).

7. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The connection terminals include a first connection terminal A (11), a first connection terminal B (12), a second connection terminal a (13) and a second connection terminal b (14); The first wiring terminal A (11) is connected to the primary winding (6), and the first wiring terminal B (12) is connected to the DC protection component; The second connecting terminal a (13) and the second connecting terminal b (14) are both connected to the secondary winding (7).

8. The DC-resistant low-voltage voltage transformer according to claim 1, characterized in that: The overcurrent protection resistor (9) is a PTC thermistor.

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