CN202093966U - A two-stem voltage transformer - Google Patents

Abstract

A mutual inductor with two core columns comprises a metal box body with an inner cavity, wherein the top and the bottom of the metal box body are respectively provided with a high-voltage sleeve and a grounding sleeve, and inert gas is filled in the metal box body; the voltage transformer square-shaped two-core column iron core is arranged at the upper part of the inner cavity of the metal box body and is electrically connected with the metal box body, and is provided with an upper core column and a lower core column, wherein an upper balance winding and a first section of primary winding are wound on the upper core column, and a second section of primary winding and a voltage transformer secondary winding are wound on the lower core column; the single-core column iron core is arranged at the lower part of the inner cavity of the metal box body and is electrically connected with the metal box body, a primary winding of the isolation transformer is wound on the single-core column iron core, an annular shielding cover is arranged around the single-core column iron core, and a secondary winding of the isolation transformer is wound in the annular shielding cover; thereby supplying power to the primary winding of the isolation transformer through the upper balance winding; the secondary winding of the isolation transformer is connected with the secondary winding of the voltage transformer in series to serve as a secondary output side.

Description

A two-stem voltage transformer

technical field

The utility model relates to a voltage transformer, in particular to a gas-insulated voltage transformer with two core column structures.

Background technique

The voltage transformer with two stems is mainly used in 110kV power system.

The structure of this kind of voltage transformer is mainly to install a square-shaped iron core in a porcelain box filled with insulating oil. The iron core has upper and lower stems, and an upper balance winding and a second stem are wound around the upper stem. One section of primary winding, the lower balance winding and the second section of primary winding are wound around the lower core, and a secondary winding is wound outside the second section of primary winding. The structure is characterized by the first section of primary winding and the second section of winding The primary winding has the same number of turns, and the upper balance winding and the lower balance winding also have the same number of turns. The inner outgoing wire of the first primary winding is connected to the inner outgoing wire of the second primary winding and then electrically connected to the iron core. Moreover, the upper balanced winding and the lower balanced winding are connected in parallel, the primary voltage is introduced from the primary terminal installed on the upper part of the porcelain box, and connected to the outer outgoing line of the first section of the primary winding, and the second section of the outer outgoing line is the low potential end, which is connected to the second The outgoing wires of the secondary winding are drawn out from the installation base of the porcelain box together.

The upper and lower balance windings function to balance the magnetic fluxes of the upper and lower core columns, which can effectively reduce the voltage ratio error of the voltage transformer. During the operation of the transformer, the voltage between the iron core and the ground is close to half of the voltage between the primary side and the ground, and the iron core needs to be fixed on the insulating support.

The advantage of using porcelain box for the voltage transformer with two-core column structure is that there is no need to consider the insulation of the iron core to the box body, but the mechanical strength of the porcelain box is low, and the oil capacity is large, which has potential safety hazards. If the primary side voltage increases, then Not only need a larger size porcelain box, but also increase the height of the porcelain box in order to meet the insulation requirements of the iron core to the ground; moreover, the bigger problem is that the capacitive current of the iron core to the ground will increase with the increase of the primary voltage. Large, making the error of the voltage transformer unstable, which limits the use of the two-stem structure voltage transformer at a higher voltage.

Utility model content

In order to overcome the potential safety hazards caused by the low mechanical strength of the porcelain box and the large oil capacity of the current two-stem structure voltage transformer, as well as the need for a larger size porcelain box when the primary voltage increases, the safety is lower, and the iron The error of the voltage transformer is unstable due to the increase of the core-to-ground capacitance current. The utility model provides a two-core voltage transformer with an improved structure to meet the requirements for use under ultra-high voltage and ultra-high voltage.

The technical scheme that the utility model adopts for solving its technical problem is:

A two-stem transformer comprising:

A metal box with an inner cavity, with a high-voltage bushing and a grounding bushing on the top and bottom respectively, and the high-voltage bushing, the grounding bushing and the inner cavity are filled with inert gas;

A voltage transformer mouth-shaped two-stem iron core arranged on the upper part of the inner cavity of the metal box and electrically connected to the metal box. It has upper and lower stems, and an upper balance is wound around the upper stem. The winding and the first section of primary winding, the lower core column is wound with the second section of primary winding and the secondary winding of voltage transformer;

An isolation transformer mouth-shaped single-column iron core arranged at the lower part of the inner cavity of the metal box and electrically connected to the metal box. The single-column iron core is wound with an isolation transformer primary winding, which surrounds the The single core column iron core is provided with an annular shielding cover, and the secondary winding of the isolation transformer is wound inside the annular shielding cover; whereby the upper balance winding supplies power to the primary winding of the isolation transformer; wherein

The secondary winding of the isolation transformer is connected in series with the secondary winding of the voltage transformer to serve as the secondary output side.

As a further improvement of the above scheme, the rated voltage ratio of the primary winding of the first section to the upper balance winding multiplied by the rated voltage ratio of the primary winding of the isolation transformer to the secondary winding of the isolation transformer is equal to the primary winding of the second section to the secondary winding of the voltage transformer The rated voltage ratio of the winding.

The working principle of the utility model is that the primary voltage is applied to the first section primary winding and the second section primary winding approximately equally, the upper balance winding wound on the upper stem is coupled with the first section primary winding, and the upper balance winding The voltage output is used as the primary input of the isolation transformer. The secondary winding of the voltage transformer wound on the lower core column is coupled with the primary winding of the second section. The voltage output of the secondary winding of the voltage transformer and the voltage output of the secondary winding of the isolation transformer are added in series as The secondary output of the gas-insulated improved two-stem voltage transformer.

，其中第一段一次绕组分得电压为

，第二段一次绕组分得电压为

，绕在上芯柱的第一段一次绕组与上平衡绕组的额定电压比为M，绕在下芯柱的第二段一次绕组与电压互感器二次绕组额定电压比为K，隔离变压器的额定电压比为N，则有： If the primary voltage applied to the two stem voltage transformers is

, where the voltage obtained by the first primary winding is

, the voltage obtained by the second primary winding is

, the rated voltage ratio of the first primary winding wound on the upper stem to the upper balanced winding is M, the rated voltage ratio of the second primary winding wound on the lower stem to the secondary winding of the voltage transformer is K, and the rated voltage of the isolation transformer is The voltage ratio is N, then:

=

In the formula:

为两芯柱电压互感器的二次输出；

is the secondary output of the two stem voltage transformers;

为电压互感器二次绕组输出；

It is the output of the secondary winding of the voltage transformer;

为隔离变压器二次绕组输出；

It is the output of the secondary winding of the isolation transformer;

为隔离变压器一次绕组输入（即也就是上平衡绕组的电压输出）；

Input for the primary winding of the isolation transformer (that is, the voltage output of the upper balanced winding);

为第一段一次绕组与上平衡绕组的变比误差；

is the transformation ratio error between the first primary winding and the upper balance winding;

是第二段一次绕组与电压互感器二次绕组的变比误差；

is the transformation ratio error between the primary winding of the second section and the secondary winding of the voltage transformer;

是隔离变压器的变比误差。

is the ratio error of the isolation transformer.

It is stipulated that K=MN during design, then:

  

According to the definition of voltage transformer error, the error of gas-insulated improved two-stem voltage transformer can be obtained as:

 

、

、都能做到足够小，从而使本实用新型的两芯柱电压互感器的误差能足够小。 Due to the tight magnetic coupling achieved by the two windings on each leg, the error component of the above equation

,

, All can be made small enough, so that the error of the two-core column voltage transformer of the utility model can be small enough.

It can be seen from the above that the utility model can use larger-sized iron cores and windings to increase the voltage level of the voltage transformer, so it can manufacture voltage transformers applied to ultra-high voltage and ultra-high voltage; and because the utility model converts the voltage The insulation level of the high-voltage bushing used by the transformer is reduced by one-half, so the cost can be saved; it can be seen that the utility model can overcome the potential safety hazard of the existing two-stem voltage transformer, and can broaden the scope of application. Save material and cost.

Description of drawings

Further description will be made below in conjunction with the accompanying drawings and specific embodiments:

Fig. 1 is a structural principle diagram of the utility model;

Fig. 2 is a schematic structural view of an embodiment of the utility model.

Part numbers in the figure:

1. The primary winding of the first section; 2. The upper balance winding; 3. The two-column iron core of the voltage transformer; 4. The primary winding of the second section; 5. The secondary winding of the voltage transformer; 6. The shape of the isolation transformer Single core column iron core; 7. Primary winding of isolation transformer; 8. Secondary winding of isolation transformer; 9. Voltage equalizing ring; 10. High voltage bushing; 11. Primary conduit; 12. Grounding bushing; 14. Terminal block; 15. Secondary wire conduit; 16. Grounding bushing capacitive screen; 17. Ring shield; 18. Metal box; 19. High voltage bushing capacitive screen.

Detailed ways

Referring to Fig. 1 and Fig. 2, in the improved gas-insulated two-stem voltage transformer provided by the utility model, the metal box 18 has an inner cavity, and the upper part of the inner cavity is provided with a voltage transformer mouth-shaped Two core column iron core 3, the lower part of the inner cavity is provided with an isolation transformer mouth-shaped single core column iron core 6, and the upper balance winding 2 and the first primary winding 1 are wound on the two-core column iron core 3 of the voltage transformer Above the upper stem, the second primary winding 4 and secondary winding 5 are wound on the lower stem of the two-leg iron core 3, and the primary winding 7 and secondary winding 8 of the isolation transformer are wound on the single-leg iron of the isolation transformer. The top of the stem of core 6.

The outer outgoing line of the first primary winding 1 passes through the high voltage bushing 10 through the primary conduit 11 and connects with the primary pressure equalizing ring 9 , the inner outgoing line of the first primary winding 1 is connected with the inner outgoing line of the second primary winding 4 connected, and electrically connected with the two-shaped core column iron core 3 of the voltage transformer.

The outer outgoing wire of the second primary winding 4 passes through the annular shielding cover 17 , passes through the grounding sleeve 12 along the secondary wire conduit 15 , and connects to the N terminal of the terminal block 14 after reaching the grounding base 13 .

The two outgoing lines of the upper balance winding 2 are connected with the two outgoing lines of the primary winding 7 of the isolation transformer wound on the square-shaped single-column core 6 of the isolation transformer, and connected with the two-column iron core 3 of the voltage transformer and the isolation transformer The square-shaped single-column iron core 6 is electrically connected.

The secondary winding 8 of the isolation transformer is installed in the grounded annular shielding cover 17, and its outgoing wires are connected with the two outgoing wires of the secondary winding 5 of the voltage transformer wound on the lower core 3 of the voltage transformer mouth-shaped two-stem core. The voltage series connection is completed in the ring-shaped shielding cover 17, and the remaining two outlets of the head and the tail pass through the ground sleeve 12 along the secondary wire conduit 15, and are connected to the a and n terminals of the terminal block 14 after reaching the ground base 13.

A high-voltage bushing capacitive screen 19 is installed at the connection between the metal box 18 and the high-voltage bushing 10, and a grounding bushing capacitive screen 16 is installed at the connection between the metal box 18 and the grounding bushing 10. The metal box 18 is designed according to the pressure vessel , the inside is filled with SF6 gas with a pressure of at least 0.4MPa; the sensor mouth-shaped two-stem core 3, and the isolation transformer mouth-shaped single-stem iron core 6 are electrically connected to the metal box 18.

As shown in Figure 2, a 1000kV two-stem voltage transformer embodiment provided by the utility model, in which the rated voltage ratio of the primary winding 4 of the first section to the upper balance winding 2 is 500kV/√3 /100V, and the second section The rated voltage ratio of the primary winding 4 to the secondary winding 5 of the voltage transformer is 500kV/√3 /50V√3, and the rated voltage ratio of the primary winding 7 of the isolation transformer to the secondary winding 8 of the isolation transformer is 100V/ 50V/√3, The rated voltage ratio of the two-stem voltage transformer is 1000kV/√3 /100V/√3. In order to balance the voltages of the primary winding 4 of the first section and the primary winding 4 of the second section, the capacitance screen 19 of the high-voltage bushing and the grounding bushing The capacitive screen 16 has different sizes, and the capacitive screen 19 of the high-voltage bushing is relatively large, and its capacitive current is nearly equal to the capacitive current of the iron core and the metal box 18 to the annular shielding cover 17 of the isolation transformer and the ground.

Certainly, the invention of the utility model is not limited to the above-mentioned embodiment, and those skilled in the art can also make equivalent modifications or replacements without violating the spirit of the utility model. within the bounds of the requirements.

Claims (8)

1. A two-stem transformer, characterized in that it comprises: A metal box with an inner cavity, with a high-voltage bushing and a grounding bushing on the top and bottom respectively, and the high-voltage bushing, the grounding bushing and the inner cavity are filled with inert gas; A voltage transformer mouth-shaped two-stem iron core arranged on the upper part of the inner cavity of the metal box and electrically connected to the metal box. It has upper and lower stems, wherein the upper stem is wound with an upper The balance winding and the first section of the primary winding, and the lower core column is wound with the second section of the primary winding and the secondary winding of the voltage transformer; An isolation transformer mouth-shaped single-column iron core arranged at the lower part of the inner cavity of the metal box and electrically connected to the metal box. The single-column iron core is wound with an isolation transformer primary winding, which surrounds the The single core column iron core is provided with an annular shielding cover, and the secondary winding of the isolation transformer is wound inside the annular shielding cover; whereby the upper balance winding supplies power to the primary winding of the isolation transformer; wherein The secondary winding of the isolation transformer is connected in series with the secondary winding of the voltage transformer to serve as the secondary output side. 2. A two-stem transformer according to claim 1, characterized in that: the rated voltage ratio of the primary winding of the first section to the upper balance winding is multiplied by the rated voltage of the primary winding of the isolation transformer to the secondary winding of the isolation transformer The voltage ratio is equal to the rated voltage ratio of the second primary winding to the secondary winding of the voltage transformer. 3 . The two-stem transformer according to claim 1 , wherein the inert gas is SF ₆ . 4. A two-stem transformer according to claim 1, characterized in that: the end of the high-voltage bushing is provided with a pressure equalizing ring, and the outer outgoing line of the first section of the primary winding passes through the primary conduit from the high-voltage bushing. The tube passes through and connects with the primary voltage equalizing ring, and the inner outlet wire of the first primary winding is connected with the inner outlet wire of the second primary winding, and is electrically connected with the square-shaped two-column iron core of the voltage transformer. 5. A two-stem transformer according to claim 1, characterized in that: the grounding bushing end is provided with a grounding base, the grounding base is provided with a terminal row, and the outer side of the second section of the primary winding The outgoing wire passes through the annular shielding cover, passes through the grounding sleeve along the secondary conduit, and connects to the N terminal of the terminal block of the grounding base. 6. A two-stem transformer according to claim 1, characterized in that: the two outgoing lines of the upper balance winding are connected to the two outgoing lines of the primary winding of the isolation transformer, and are connected to the voltage transformer The two core column iron cores are electrically connected to the square-shaped single core column iron core of the isolation transformer. 7. A transformer with two core columns according to claim 5, characterized in that: the outgoing wires of the secondary winding of the isolation transformer and the two outgoing wires of the secondary winding of the voltage transformer are connected in series in the annular shielding cover, The first and last outgoing wires of the secondary winding of the isolation transformer pass through the grounding bushing along the secondary conduit, and are connected to the a terminal and the n terminal of the terminal block of the grounding base. 8. A two-stem transformer according to claim 1, characterized in that: a high-voltage bushing capacitive screen is installed at the connection between the metal box and the high-voltage bushing, and the metal box is connected to the grounding bushing A grounded bushing capacitive screen is installed.

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