CN104124044A - Capacity-adjusting and voltage-adjusting three-phase transformer - Google Patents

Abstract

The invention relates to a capacity-regulating and voltage-regulating three-phase transformer, which adjusts the output capacity and output voltage of the transformer by tracking load changes and secondary voltage fluctuations. When the three-phase transformer has a large capacity, the high-voltage windings are delta-connected, and the low-voltage windings of each phase are connected in parallel with the second winding and the third winding and then connected in series with the first winding; The low-voltage windings of each phase are connected in series by three sections of windings. Terminals at both ends of each winding on the high-voltage side and the low-voltage side of the three-phase transformer are respectively connected to corresponding terminals of the capacity-regulating and voltage-regulating switch. The high-voltage windings of each phase of the transformer are divided into two sections of windings, at least one of the windings on the two sections of windings has at least one tap, and each tap is connected to the corresponding terminals of the voltage regulation and capacity regulation switch. The output capacity and output voltage can be adjusted by switching the action of the motor mechanism.

Description

A capacity-adjusting and voltage-regulating three-phase transformer

technical field

The invention relates to a capacity-regulating and voltage-regulating three-phase transformer, which belongs to the field of power systems.

Background technique

The rated capacity of the current distribution transformers in my country, including box-type substations, is mostly fixed and configured according to the maximum load of the user. However, my country's rural power grids often show seasonal uneven power consumption (for example, full load or even overload during the busy farming season and the Spring Festival, while the load is small at other times) and low average load rate (the annual average load rate of transformers in some areas is even lower than 25 %)Features. This causes the reactive power component of the power grid to be too large, and the ratio of transformer no-load loss to transmission capacity is too large, so that a large amount of electric energy is wasted in reactive current loss and transformer no-load loss. A small number of on-load capacity regulating transformers appearing in the market can partially solve the above problems, but they have a single function, which can only adjust the output capacity, and cannot adjust the output capacity and output voltage at the same time. It is difficult to meet the development requirements of energy-saving, intelligent, high-efficiency, and stable power supply quality in the field of power transformation and distribution in my country.

Contents of the invention

The purpose of the present invention is to provide a three-phase transformer with capacity and voltage regulation, which is used to solve the problem that the output capacity and output voltage of the transformer cannot be adjusted at the same time according to the change of the load size and the level of the grid voltage, so as to reduce the no-load loss and The problem of stabilizing the output voltage.

In order to achieve the above object, the solution of the present invention is a three-phase transformer with capacity and voltage regulation. The low-voltage windings of each phase of the three-phase transformer include a first winding, a second winding and a third winding, and the wire cross-sectional area of the first winding is the second Two times the second winding or the third winding, the number of turns of the second winding and the third winding are the same.

When the transformer load is within the set large-capacity range, the high-voltage windings of the three-phase transformer are connected in delta, and the low-voltage windings of each phase are connected in parallel with the second winding and the third winding and then connected in series with the first winding.

When the transformer load is within the set small capacity range, the high-voltage windings of the three-phase transformer are star-connected, and the low-voltage windings of each phase are the first winding, the second winding, and the third winding in series.

The terminals at both ends of the high-voltage windings of each phase and the terminals at both ends of the first winding, the second winding and the third winding of the low-voltage windings of each phase are respectively connected to the corresponding terminals of the capacity-regulating and voltage-regulating switches.

The high-voltage windings of each phase of the three-phase transformer are divided into the fourth winding and the fifth winding. At least one of the fourth winding and the fifth winding has at least one tap in the middle of the high-voltage winding of the phase. on the corresponding terminal of the voltage regulating switch.

The capacity-regulating and voltage-regulating switch is an on-load capacity-regulating and voltage-regulating switch, and the on-load capacity-regulating and voltage-regulating switch is installed in the oil tank of the three-phase transformer.

The three-phase transformer is equipped with a control cabinet, which includes: transformer 11, control cabinet body 12, three-phase four-wire multi-function electric meter 13, power consumption management terminal 14, capacitor bank control switch 15, controller 16, intelligent low-voltage load Switch 17, common supplementary capacitor bank 18, subcomplementary capacitor bank 19, incoming line circuit breaker 20, outgoing line circuit breaker 21.

The invention automatically adjusts the output capacity and output voltage of the terminal distribution transformer by tracking load changes and secondary voltage fluctuations, and has the characteristics of high intelligence, compact structure, and convenient installation.

Description of drawings

Figure 1 is a schematic diagram of the winding connection when the three-phase transformer has a large capacity;

Figure 2 is a schematic diagram of the winding connection when the three-phase transformer has a small capacity;

Fig. 3 is a schematic diagram of the structure of the control cabinet;

Figure 4 is an overall schematic diagram of the three-phase transformer and the control cabinet.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Figure 1 and Figure 2 are the basic principle wiring diagrams of capacity and voltage regulating three-phase transformers. Figure 1 is the wiring diagram of the three-phase transformer at large capacity. When the three-phase transformer is at large capacity, the high-voltage winding is delta-connected, and the low-voltage winding of each phase is connected in parallel by two windings 2 and 3 and then connected in series with 1. Figure 2 is the wiring diagram of the three-phase transformer at a small capacity. When the three-phase transformer is at a small capacity, the high-voltage winding of the transformer is changed to a star connection to ensure that the current density in the wire remains basically unchanged. The low-voltage winding consists of 1, 2, 3 Three-section windings are connected in series. Since the number of turns of the low-voltage winding increases at this time, the magnetic flux density in the iron core is greatly reduced, which can significantly reduce the no-load loss and noise of the transformer. The wire cross-sectional area of winding 1 is twice that of winding 2 or winding 3, and the number of turns of winding 2 and 3 is the same. The terminals at both ends of each winding on the high-voltage side and low-voltage side of the three-phase transformer are respectively connected to the corresponding terminals of the on-load capacity-regulating and voltage-regulating switch, and the three-phase transformer is changed by the action of the switch motor mechanism in the on-load capacity-regulating and voltage-regulating switch. The change of the connection mode of the high-voltage winding and the series-parallel connection of the low-voltage winding realizes the adjustment of the output capacity of the transformer.

The high-voltage windings of each phase of the three-phase transformer are divided into two windings, which are windings 4 and 5, as shown in Figure 1 or 2. On 4 or 5, there are several taps, and each tap is connected to each corresponding terminal of the on-load voltage regulation and capacity regulating switch. connection sequence, the output voltage can be adjusted. When working, first preset an ideal secondary output voltage and a very poor voltage. When the grid voltage fluctuates, the secondary voltage will change. When the change exceeds the range voltage, the electric mechanism of the switch will act to change the tap position on the high voltage side of the transformer, so that the secondary voltage will return to the preset voltage range.

The capacity regulation and pressure regulation are integrated in an on-load capacity regulation and voltage regulation switch, and share an electric operating mechanism, which reduces the size and cost of the switch. The on-load capacity regulating and voltage regulating switch is installed in the oil tank of the three-phase transformer, and is connected with each terminal of the transformer through internal wiring.

The terminals of the high and low voltage windings of the transformer and the taps of the high voltage winding are respectively connected to the corresponding static terminals of the on-load capacity regulating switch in the oil tank of the transformer. When capacity adjustment is required, the electric mechanism of the on-load capacity adjustment and voltage adjustment switch drives the moving terminal of the corresponding switch to change the connection mode of the transformer winding and the change of series and parallel connections, so as to realize the adjustment of the output capacity of the transformer; when the output voltage needs to be adjusted , can also be realized by changing the tap position of the high-voltage winding through the electric mechanism.

Figure 3 is a control cabinet equipped with a three-phase transformer. The control cabinet includes a transformer 11, a control cabinet body 12, a three-phase four-wire multi-function meter 13, a power consumption management terminal 14, a capacitor bank control switch 15, a controller 16, an intelligent low-voltage load switch 17, a common compensation capacitor bank 18, Sub-complement capacitor bank 19, incoming circuit breaker 20, outgoing circuit breaker 21. The principle of the control cabinet is to use the transformer to detect the output current and output voltage of the three-phase transformer as the control signal of the controller to determine whether the capacity and voltage regulation switch operates. And intelligent low-voltage load switch, realize reactive power compensation, adjust three-phase unbalance and other functions.

The transformer is connected to the intelligent control cabinet through a common base, as shown in Figure 4, which is an overall schematic diagram, including: a common base 31, a three-phase transformer 32, an on-load capacity regulating switch 33, and a control cabinet 34, realizing an integrated design. It facilitates on-site installation.

Specific embodiments have been given above, but the present invention is not limited to the described embodiments. The basic idea of the present invention lies in the above-mentioned basic scheme. For those of ordinary skill in the art, according to the teaching of the present invention, it does not need to spend creative labor to design various deformation models, formulas, and parameters. Changes, modifications, substitutions and variations to the implementations without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (3)

1. a capacity and pressure regulating three-phase transformer, it is characterized in that, each phase low pressure winding of described three-phase transformer comprises the first winding, the second winding and the tertiary winding, and the sectional area of wire of the first winding is the twice of the second winding or the tertiary winding, and the number of turn of the second winding and the tertiary winding is identical;

In the time of between the large capacity region of transformer load in setting, the high pressure winding of described three-phase transformer is that triangle connects, each phase low pressure winding be the second winding in parallel with the tertiary winding after with the first windings in series;

In the time of in the low capacity interval of transformer load in setting, the high pressure winding of described three-phase transformer is Y-connection, and each phase low pressure winding is that the first winding, the second winding, the tertiary winding are connected successively;

The two end terminals of the first winding of the two end terminals of each phase high pressure winding and each phase low pressure winding, the second winding, the tertiary winding is connected with each respective terminal of capacity and pressure regulating switch respectively;

Each phase high voltage winding component of described three-phase transformer is the 4th winding and the 5th winding, in described the 4th winding and the 5th winding, have at least a winding to have at least one tap at the place, middle part of this phase high pressure winding, described tap is connected in the respective terminal of capacity and pressure regulating switch.

2. capacity and pressure regulating three-phase transformer according to claim 1, is characterized in that, described capacity and pressure regulating switch is loaded capacity regulating voltage regulating switch, and described loaded capacity regulating voltage regulating switch is arranged in the fuel tank of described three-phase transformer.

3. capacity and pressure regulating three-phase transformer according to claim 2, it is characterized in that, described three-phase transformer is equipped with control cubicle, and this control cubicle comprises: instrument transformer (11), control cubicle cabinet (12), three-phase and four-line multifunction electric meter (13), electricity management terminal (14), capacitor group control switch (15), controller (16), intelligent low-pressure on-load switch (17), mend capacitor group (18), minute benefit capacitor group (19), lead-in circuit breaker (20), wire-outgoing breaker (21) altogether.