CN207367766U - A kind of built-in transformer current-limiting apparatus - Google Patents

Abstract

It the utility model is related to a kind of built-in transformer current-limiting apparatus.Its main feature is that：Including the first branch, the second branch and the 3rd branch, the first branch, the second branch and the 3rd respective one end of branch connect three-winding transformer (1) on high-tension side neutral point at the same time and its other end draws connect line end and C connects line end as connect line end, B of A respectively, and the wherein first branch, the second branch and the 3rd branch is composed in parallel by capacitor (2), current-limiting reactor (3) and high-speed switch (4) three.The utility model has significant advantages and beneficial effects compared with prior art, is embodied in the following aspects：Using the built-in current-limiting apparatus of the utility model, realize the automatic switching of current-limiting reactor, impedance from main regulation, reduce short circuit current flow to newly developing transformer and the impact in fortune transformer, while reduce loss, easy to maintain.Transformer reactance device integrated design can be realized using the built-in current-limiting apparatus of the utility model.

Description

A built-in transformer current limiting device

technical field

The utility model relates to a built-in transformer current limiting device.

Background technique

With the application of large-capacity power transformers, the short-circuit current also increases, and the occurrence of short-circuit faults will endanger the dynamic and thermal stability of the transformer. The built-in transformer current-limiting device is different from the traditional current-limiting device. Its main working principle is: the current-limiting device is placed in the transformer oil tank, and the fast switch in the current-limiting device is connected in parallel with the current-limiting reactor. The switch is closed, and the current-limiting reactor is short-circuited; when a short-circuit fault occurs, the fast switch is disconnected, and the current-limiting reactor is connected to increase the impedance to limit the short-circuit current. When the overvoltage across the reactor.

The built-in current limiting device is more suitable for use in new transformers. Compared with other types of current limiting devices, the built-in current limiting device has the remarkable characteristics of quick action, strong breaking capacity, excellent current limiting effect and energy saving. A current-limiting reactor is connected in parallel with a fast switch to reduce losses during normal operation of the transformer. However, the high-impedance characteristics of existing high-impedance transformers are not conducive to energy saving during normal operation of the system, and the economy is relatively poor. At the same time, the higher the impedance voltage of the transformer, the larger the size of the transformer and the higher the manufacturing cost.

Utility model content

The purpose of this utility model is to provide a built-in transformer current limiting device, which can overcome the deficiencies in the prior art. When a short-circuit fault occurs, a current-limiting reactor is used to limit the current, reducing the impact of the short-circuit current on the transformer and extending the Transformer life.

A built-in transformer current limiting device, which is special in that it includes a first branch, a second branch and a third branch, and one end of each of the first branch, the second branch and the third branch is simultaneously Connect to the neutral point of the high-voltage side of the three-winding transformer and lead out the other end as the A-phase terminal, B-phase terminal and C-phase terminal respectively, wherein the first branch, the second branch and the third branch are all connected by A capacitor, a current-limiting reactor and a fast switch are connected in parallel.

It includes a shielded aluminum cylinder with openings at both ends. The two ends of the shielded aluminum cylinder are respectively equipped with pot insulators through flanges. Between the two pot insulators in the shielded aluminum cylinder, a capacitor fast switch parallel device, ring An epoxy resin cylinder on which a current-limiting reactor coil is wound.

Wherein the capacitor fast switch parallel device includes parallel capacitors and fast switches.

Wherein the bottom of the epoxy resin cylinder is provided with an epoxy resin cylinder support, and the bottom of the epoxy resin cylinder support is connected with the flange at the bottom of the shielding aluminum cylinder.

Wherein the epoxy resin cylinder is connected with the epoxy resin cylinder support through a flange.

The top of the epoxy resin cylinder is connected to the bottom of the capacitor fast switch parallel device through a flange.

Compared with the prior art, the utility model has significant advantages and beneficial effects, which are embodied in the following aspects: using the built-in current limiting device of the utility model, the automatic switching of the current limiting reactor and the independent adjustment of the impedance are realized. Reduce the impact of short-circuit current on newly developed transformers and transformers in operation, while reducing losses and facilitating maintenance. The integrated design of the transformer reactor can be realized by using the built-in current limiting device and method of the utility model.

Description of drawings

Accompanying drawing 1 is the circuit schematic diagram of the utility model;

Accompanying drawing 2 is the structural representation of the utility model.

Detailed ways

As shown in Figures 1 and 2, the utility model provides a built-in transformer current limiting device, including a first branch, a second branch and a third branch, the first branch, the second branch and the first branch One end of each of the three branches is connected to the neutral point of the high-voltage side of the three-winding transformer 1 at the same time, and the other end is respectively led out as the A-phase terminal, the B-phase terminal and the C-phase terminal, wherein the first branch, the second branch The circuit and the third branch are composed of capacitor 2, current-limiting reactor 3 and fast switch 4 connected in parallel.

The specific structure of the device of the present invention includes a shielding aluminum cylinder 7 with openings at both ends, and pot insulators 5 are respectively installed on the two ends of the shielding aluminum cylinder 7 through flanges 6, and between the two pot insulators 5 are sequentially installed Capacitor fast switch parallel device 8 , epoxy resin cylinder 10 , on which a current-limiting reactor coil 11 is wound. Wherein the capacitor fast switch parallel device 8 includes a capacitor 2 and a fast switch 4 connected in parallel. Wherein the bottom of the epoxy resin cylinder 10 is provided with an epoxy resin cylinder bracket 12, the bottom of the epoxy resin cylinder bracket 12 is connected with the flange 6 at the bottom of the shielded aluminum cylinder 7, and the top of the capacitor quick switch parallel device 8 is connected with the top of the shielded aluminum cylinder 7. Flange 6 does not touch.

Wherein the epoxy resin cylinder 10 is connected with the epoxy resin cylinder bracket 12 through the flange 6 . In addition, the top of the epoxy resin cylinder 10 is connected to the bottom of the capacitor fast switch parallel device 8 through the flange 6 .

A method for limiting a transformer short circuit, comprising the steps of:

(1) Between the high-voltage winding and the neutral point of the three-phase three-winding transformer, a current-limiting reactor 3 that meets the current-limiting requirements is connected in series;

(2) The fast switch 4 is connected in parallel at both ends of the current-limiting reactor 3. When the short-circuit current occurs, when the short-circuit current crosses zero, the fast switch 4 is put into the current-limiting reactor 3, and when the transformer is in normal operation, the limit The flow reactor 3 is short-circuited by the fast switch 4 .

The current limiting requirement in step (1) means that the short-circuit current should be limited to less than 60% of the original short-circuit current. For example, take a 63MVA, 110/38.5/10.5kV transformer as an example. The short-circuit impedance percentage of the high and high windings of the _transformer is 10.5%. Then the reactance value of the reactor should not be less than the reactance value required to limit the 40% short-circuit current

In step (1), a capacitor 2 is connected in parallel at both ends of the current-limiting reactor 3, so as to limit the transient overvoltage generated at both ends of the current-limiting reactor 3 when it is put into operation.

Example 1:

The utility model is described in further detail below in conjunction with the accompanying drawings: as shown in Figure 1, it includes a three-winding transformer 1, a capacitor 2, a current-limiting reactor 3, and a fast switch 4.

A built-in transformer current-limiting device, including a current-limiting reactor coil 11, an aluminum cylinder, a pot insulator 5, a flange 6, an epoxy resin cylinder 10, a quick switch 4, and a capacitor 2. It is characterized by a current-limiting reactor 3 , fast switch 4 and capacitor 2 are connected in parallel.

Referring to Fig. 2, it is a structure of a built-in transformer current limiting device of the present invention, including pot insulator 5, flange 6, shielding aluminum cylinder 7, capacitor quick switch parallel device 8, SF ₆ air hole 9, epoxy resin Cylinder 10, current-limiting reactor coil 11, and epoxy resin cylinder bracket 12, wherein the radial distance between aluminum cylinder 7 and coil 11 is set at about 50 mm to reduce the influence of shielded aluminum cylinder 7 on the reactance value of current-limiting reactor 3, and the current-limiting A reactor coil 11 is wound on the epoxy resin barrel 10 . The distance between the flange 6 and the current-limiting reactor coil 11 is about 100 mm. On the one hand, the effect of eddy current in the aluminum flange 6 is reduced, and on the other hand, the short-circuit electromotive force generated in the flange 6 is reduced to avoid damage to the pot The insulator 5 brings unbearable short-circuit impact.

A method for limiting a short circuit of a transformer using the above-mentioned device, comprising the following steps:

(1) Between the high-voltage winding and the neutral point of the three-phase transformer, a reactor that meets the current limiting requirement (60% short-circuit current) is connected in series;

(2) Install the current-limiting reactor 3 automatic switching device: the fast switch 4 is connected in parallel at both ends of the current-limiting reactor 3. When the short-circuit current occurs, the current-limiting reactor 3 can be quickly switched on when the short-circuit current crosses zero, and the transformer is normal. During operation, the current-limiting reactor 3 is short-circuited;

(3) In order to limit the transient overvoltage generated by inputting the current-limiting reactor 3 at its two ends, a capacitor 2 with a certain capacitance value is connected in parallel at its two ends.

The structure of the built-in transformer current limiting device of the utility model has the advantages of energy saving and fast action, and reduces the impact of short-circuit current on the transformer winding. Utilize the technical solution described in the utility model, or those skilled in the art design a similar technical solution under the inspiration of the technical solution of the utility model, and achieve the above-mentioned technical effect, all fall into the protection of the utility model scope.

Claims (6)

1. A kind of 1. built-in transformer current-limiting apparatus, it is characterised in that：, should including the first branch, the second branch and the 3rd branch The first branch, the second branch and the 3rd respective one end of branch connect three-winding transformer (1) on high-tension side neutral point at the same time and its The other end is drawn respectively connects line end and C connects line end, the wherein first branch, the second branch and as connect line end, B of A Three branches are composed in parallel by capacitor (2), current-limiting reactor (3) and high-speed switch (4) three.
2. A kind of 2. built-in transformer current-limiting apparatus as claimed in claim 1, it is characterised in that：Shielding including both ends open Aluminum barrel (7), the both ends of the shielding aluminum barrel (7) are provided with disc insulator (5) by flange (6) respectively, in the shielding aluminum barrel (7) Quick switch of capacitor shunting means (8), epoxy resin cylinder (10) are sequentially installed between two interior disc insulators (5), Current-limiting reactor coil (11) is wound with the epoxy resin cylinder (10).
3. A kind of 3. built-in transformer current-limiting apparatus as claimed in claim 2, it is characterised in that：Wherein Quick switch of capacitor Shunting means (8) includes capacitor (2) and high-speed switch (4) in parallel.
4. A kind of 4. built-in transformer current-limiting apparatus as claimed in claim 2, it is characterised in that：Its epoxy resin cylinder (10) Bottom is equipped with epoxy resin tube stent (12), the flange (6) of epoxy resin tube stent (12) bottom and shielding aluminum barrel (7) bottom Connection.
5. A kind of 5. built-in transformer current-limiting apparatus as claimed in claim 4, it is characterised in that：Its epoxy resin cylinder (10) It is connected by flange (6) with epoxy resin tube stent (12).
6. A kind of 6. built-in transformer current-limiting apparatus as claimed in claim 2, it is characterised in that：Its epoxy resin cylinder (10) Top is connected by flange (6) with Quick switch of capacitor shunting means (8) bottom.