CN201126755Y - A Transformer Structure That Improves Impedance - Google Patents

Abstract

The utility model discloses a low-cost and impedance-improved transformer structure. Including a single-phase current-limiting reactor, the single-phase current-limiting reactor is arranged outside the side column of the iron core in the transformer oil tank, and the single-phase current-limiting reactor is connected in series with the single-phase winding in the single-phase transformer oil tank; the utility model The new type can also include a three-phase current-limiting reactor, and the three-phase current-limiting reactor is arranged on the outside of the iron core side column in the oil tank of the three-phase transformer in the oil tank, and is arranged perpendicular to the direction of arrangement of the three-phase windings; the three-phase current-limiting reactor The reactor is connected in series with the three-phase winding in the transformer oil tank, and forms a star or delta electrical connection.

Description

A Transformer Structure That Improves Impedance

technical field

The utility model relates to a transformer structure.

Background technique

With the increase of urban electricity consumption, in order to reduce the investment in primary substations, it has become a new market demand for the low-voltage side of high-voltage large-capacity transformers to be directly connected to urban power grids. This type of transformer has two basic requirements: one is low-voltage High impedance is required on the low-voltage side to reduce the short-circuit current on the low-voltage side, which is conducive to the selection of low-voltage circuit breakers. Second, the medium-voltage side still requires zero impedance or close to zero impedance to facilitate grid operation. As the capacity of the transformer increases, the short-circuit current on the low-voltage side (10-66kV side) increases, see formula (1):

Ik＝IH×100/Uk                                        

In the formula: Ik----short circuit current

IH - rated current

Uk--transformer impedance voltage.

If the impedance voltage remains unchanged, its short-circuit current increases with the increase of capacity. The increase of the short-circuit current brings certain difficulties to the circuit breaker on the 10-66kV side to select the breaking current, and at the same time increases the investment of the circuit breaker. If the short-circuit current is to be reduced, the impedance voltage must be increased. In order to increase the impedance voltage, the methods currently used are: (1) Connecting a current-limiting reactor in series with the bus on the low-voltage side of the transformer. The disadvantages are: increased investment, large substation footprint, and low feasibility. (2) Increase the impedance voltage Uk of the transformer to limit the short-circuit current. Its disadvantages are: the cost of the transformer is high, the load loss is relatively large, and the economy is slightly poor during operation.

Contents of the invention

In view of the above problems, the utility model provides a low-cost transformer structure with improved impedance.

In order to achieve the above object, the utility model is realized by taking the following technical solutions:

A transformer structure capable of improving impedance, including a single-phase current-limiting reactor, characterized in that the single-phase current-limiting reactor is arranged outside the side column of the iron core in the single-phase transformer oil tank, and the single-phase current-limiting reactor is placed on the The transformer oil tank is connected in series with the single-phase low-voltage winding; after the series connection, the other end of the current-limiting reactor and the low-voltage terminal of the single-phase winding lead out of the transformer oil tank.

Another transformer structure for improving impedance, including a three-phase current-limiting reactor, is characterized in that the three-phase current-limiting reactor is arranged outside the side column of the iron core in the oil tank of the three-phase transformer, and is arranged perpendicular to the three-phase winding Directional arrangement; the three-phase current-limiting reactor is connected in series with the three-phase winding in the transformer oil tank, and forms a star or delta electrical connection. The low-voltage terminals a, b, and c connected in the triangle electric connection lead out from the oil tank to connect to the transformer bushing. The star-shaped electrical connections are connected together in the transformer oil tank, and lead out of the oil tank as a neutral point.

The utility model has the advantages that the low-voltage winding and the current-limiting reactor are connected in series inside the transformer, and all electrical connections are completed inside the transformer, so the insulation structure is simple, the amount of copper wire can be greatly saved, the cost is reduced, and the load loss of the transformer is low. The transformer is easy to install and has high reliability.

Description of drawings

Fig. 1 is a top view of a single-phase transformer structure of an inner-series single-phase current-limiting reactor of the present invention. In the figure, 1. One-way current-limiting reactor; 1', single-phase winding on the low-voltage side of the transformer; 4. Iron core side column; 5. Oil tank.

Fig. 2 is a top view of another three-phase transformer structure of an inner-series three-phase current-limiting reactor of the present invention. In the figure, 1, 2, and 3 are three-phase current-limiting reactors; 1'2'3' are transformer three-phase windings.

Fig. 3 is a wiring diagram (star connection) of the three-phase current-limiting reactor in Fig. 2 in the oil tank of the three-phase transformer.

Fig. 4 is another wiring diagram (delta connection) of the three-phase current-limiting reactor in Fig. 2 in the oil tank of the three-phase transformer.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail.

Example 1

As shown in Figure 1, a single-phase transformer with a single-phase current-limiting reactor connected in series includes a single-phase current-limiting reactor 1, which is arranged on the side of the single-phase winding 1' on the low-voltage side of the transformer in the oil tank 5 (next to the iron core column 4), the single-phase current-limiting reactor 1 is connected in series with the single-phase winding 1' in the transformer oil tank 5, after being connected in series, the other end of the current-limiting reactor 1 and the low voltage of the single-phase winding 1' The terminal leads out of the transformer oil tank 5.

Example 2

As shown in Figure 2 and Figure 3, another three-phase transformer structure in which three-phase current-limiting reactors are connected in series includes three-phase current-limiting reactors 1, 2, and 3, which are arranged in the oil tank 5 on the low-voltage side of the three-phase transformer. One side of the winding 1'2'3' arrangement direction (the outside of the iron core side column 4), and is arranged perpendicular to the three-phase winding arrangement direction; the three-phase current-limiting reactor 1, 2, 3 is in the oil tank 5 and the The three-phase windings 1'2'3' are connected in series to form a star connection. The specific electrical connection is shown in Figure 3. One end of the current-limiting reactor 1 is connected in series with the x-end of the winding 1', one end of the current-limiting reactor 2 is connected in series with the y-end of the winding 2', and one end of the current-limiting reactor 3 is connected in series. It is connected in series with the z terminal of the winding 3'. After the other ends of the current-limiting reactors 1, 2, and 3 are connected at three points, they are used as the neutral point o to lead out the transformer. The low-voltage terminals a, b, and c of the three-phase winding 1'2'3' are connected to the transformer bushing.

Example 3

As shown in Figure 2 and Figure 4, the third type of three-phase transformer low-voltage side structure with three-phase current-limiting reactors in series includes three-phase current-limiting reactors 1, 2, and 3, which are arranged in the single-phase transformer in the oil tank 5 The outer side of the side column of the iron core is arranged perpendicular to the arrangement direction of the three-phase windings; the three-phase current-limiting reactors 1, 2, 3 are connected in series with the three-phase windings 1'2'3' in the oil tank 5 respectively to form a delta connection. The specific electrical connection is shown in Figure 4. One end of the current limiting reactor 1 is connected in series with the x end of the winding 1', one end of the current limiting reactor 2 is connected in series with the y end of the winding 2', and one end of the current limiting reactor 3 is connected in series. It is connected in series with the z terminal of the winding 3'. The other end of the current limiting reactor 1 is connected to the b end of the winding 2'; the other end of the current limiting reactor 2 is connected to the c end of the winding 3'; the other end of the current limiting reactor 3 is connected to the a end of the winding 1', three-phase Winding low-voltage terminals a, b, c are connected to transformer bushings.

Claims (3)

1. A transformer structure capable of improving impedance, comprising a single-phase current-limiting reactor, characterized in that the single-phase current-limiting reactor is arranged on the outside of the iron core side column in the single-phase transformer oil tank, and the single-phase current-limiting reactor The reactor is connected in series with the single-phase winding in the transformer oil tank; after being connected in series, the other end of the current-limiting reactor and the low-voltage terminal of the single-phase winding lead out of the transformer oil tank. 2. A transformer structure capable of improving impedance, including a three-phase current-limiting reactor, characterized in that the three-phase current-limiting reactor is arranged outside the side column of the iron core in the oil tank of the three-phase transformer, and is perpendicular to the three-phase current-limiting reactor. The phase windings are arranged in the direction of arrangement; the three-phase current-limiting reactor is connected in series with the three-phase windings in the transformer oil tank to form a star or delta electrical connection; the low-voltage terminals a, b, and c of the three-phase windings lead out from the oil tank to connect to the transformer sleeve Tube. 3. The transformer structure capable of increasing impedance according to claim 2, characterized in that the star-shaped electrical connections are connected together in the transformer oil tank, and lead out of the oil tank as a neutral point.

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