A precise phase control closing device for suppressing transformer inrush current

Abstract

The application is a precise phase control closing device for inhibiting transformer inrush current, which uses precise phase control closing device and combines with residual magnetism calculation technology to realize zero inrush current operation of no-load transformer. The precise phase control closing device includes three measurement PTs, an execution unit and a comprehensive command unit. When the transformer needs to be put into operation, the comprehensive command unit selects and sets the closing angle according to the residual magnetism data and the signal of the upper measurement PT of the execution unit to control the execution unit to turn on the closing, and the transformer is put into operation without inrush current. When the transformer exits operation, the comprehensive command unit commands the fast circuit breaker in the execution unit to realize the fast breaking function, and the comprehensive command unit automatically calculates the residual magnetism of the transformer according to the signals of the lower measurement PT and the measurement CT of the execution unit to prepare for the next operation. The application has the advantages of safety and reliability, protection of transformers and other auxiliary equipment from the impact of inrush current during closing, and improvement of the operation life of the equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of transformer closing inrush current suppression and power electronics, and particularly relates to a precise phase control closing device for suppressing transformer closing inrush current. BACKGROUND

[0002] With the development of economy and the sharp increase of power load, in order to adapt to the growth of load, more and more large capacity and super large capacity transformers are put into application, and when the large transformer is put into operation, closing inrush current is inevitably generated, which causes impact on the transformer and the system, reduces the service life of the transformer, and affects the stability of the power system operation. In order to solve the impact of inrush current on the transformer and the system, the phase closing strategy applied in the market now has limitations in technical principle and hardware execution mechanism, either cannot calculate residual magnetism or cannot realize precise closing, thereby leading to poor suppression effect on transformer closing inrush current.

[0003] From the development of power grid, suppressing transformer closing inrush current is a problem that must be broken through, and the most promising and most complete method at present is the precise phase control closing method according to the residual magnetism of the transformer, so a precise phase control closing device for suppressing transformer closing inrush current is developed. SUMMARY

[0004] The precise phase control closing device for suppressing transformer closing inrush current provided by the present application can solve the above technical problems.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] A precise phase control closing device for suppressing transformer closing inrush current, comprising a measurement PT1, a measurement PT2, a measurement CT3, an execution unit and a comprehensive command unit;

[0007] One end of the measurement PT1 is connected with a bus, and the other end is grounded;

[0008] The incoming line end of the execution unit is connected with the bus, the outgoing line end of the execution unit is connected in series with the high voltage end of the measurement PT2, and the low voltage end of the measurement PT2 is grounded;

[0009] The incoming line end of the measurement CT3 is connected in series with the outgoing line end of the execution unit, and the outgoing line end of the measurement CT3 is the outgoing line end of the device;

[0010] The comprehensive command unit uses the measurement PT to monitor the power supply side voltage signal in real time, and when the transformer needs to be put into operation, the execution unit is selected to issue a command according to the voltage signal;

[0011] When the transformer is out of operation, the integrated command unit executes the opening command according to the circuit breaker in the execution unit, and calculates the residual magnetism of the transformer core according to the voltage and current signals of the load side detected by the measuring PT and the measuring CT, so as to prepare for the next transformer closing operation.

[0012] Further, the execution unit is composed of circuit breakers and bidirectional thyristors, and the B and C phase circuit breakers are connected in parallel with the bidirectional thyristors (SCR) except for the A phase circuit breaker.

[0013] As can be seen from the above technical solution, the precise phase control closing device for suppressing inrush current of transformer closing has the advantages of protecting the transformer and other auxiliary equipment from the impact of inrush current, safety and reliability, and simple operation. When the transformer needs to be put into operation, the integrated command unit selects an ideal closing angle according to the residual magnetism data and the signal of the measuring PT to control the execution unit to close, so as to put the transformer into operation without inrush current. When the transformer is out of operation, the integrated command unit automatically calculates the residual magnetism of the transformer according to the signals of the lower end measuring PT and the measuring CT of the execution unit, so as to prepare for the next operation. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is the schematic diagram of the patent system of the present application;

[0015] Figure 2 is the electrical connection principle diagram of the execution unit in the patent of the present application;

[0016] Figure 3 is the control action logic diagram of the integrated command unit of the patent of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments.

[0018] As Figure 1 shown, a precise phase control closing device for suppressing inrush current of transformer closing utilizes a precise phase control closing device and combines residual magnetism precise calculation technology to realize zero inrush current operation of no-load transformer. The precise phase control closing device comprises a measuring PT1, a measuring PT2, a measuring CT3, an execution unit 4 and an integrated command unit.

[0019] One end of the measuring PT1 is connected with a bus, and the other end is grounded. The incoming line end of the execution unit 4 is connected with the bus, and the outgoing line end of the execution unit 4 is connected in series with the high voltage end of the measuring PT2, and the low voltage end of the measuring PT2 is grounded. The incoming line end of the measuring CT3 is connected in series with the outgoing line end of the execution unit 4, and the outgoing line end of the measuring CT3 is the outgoing line end of the device.

[0020] The measuring PT1 and the measuring PT2 are high-precision voltage transformers; the measuring CT3 is a high-precision current transformer, and the loop current is monitored in real time.

[0021] The execution unit 4 (as shown in the attached Figure 2 ) is composed of a high-speed circuit breaker (K) and a bidirectional thyristor (SCR), and the circuit breakers (K) of the B and C phases are connected in parallel with the bidirectional thyristors (SCR) except for the circuit breaker (K) of the A phase.

[0022] The high-speed circuit breaker (K) in the execution unit 4 has a closing time of ≯10 ms and an opening time of ≯5 ms, can quickly open the fault current, has high reliability and stability, and has an operating life of more than 10,000 times.

[0023] The bidirectional thyristor (SCR) in the execution unit 4 has a microsecond conduction characteristic, has a conduction zero dispersion degree, and has a zero pre-discharge precise conduction characteristic.

[0024] The comprehensive command unit uses the measuring PT1 to monitor the power supply side voltage signal in real time, and selects a suitable timing for issuing a command to the execution unit according to the voltage signal when the transformer needs to be put into operation.

[0025] When the transformer is taken out of operation, the comprehensive command unit calculates the residual magnetism of the transformer core according to the voltage and current signals detected by the measuring PT2 and the measuring CT3 after the execution unit 4 is opened, and prepares for the next transformer closing operation.

[0026] The working principle is as follows: as Figure 1 , Figure 2 , Figure 3 , the controller internally stores the initial residual magnetism of the transformer, uses the measuring PT1 to monitor the power supply side voltage signal in real time, and automatically calculates the conduction closing timing of the execution unit 4 according to the residual magnetism and the voltage signal and issues an execution command when the transformer needs to be put into operation. When the execution unit 4 receives the closing command, the A-phase circuit breaker is closed first, the single-phase conduction loop does not generate current, the B-phase thyristor (SCR) is turned on after a delay of 20 ms, and then the C-phase thyristor (SCR) is turned on. The microsecond conduction characteristic of the thyristor is used to realize precise phase control conduction, so as to realize zero inrush current power-on of the transformer to be put into operation; during the continuous conduction of the B and C phase thyristors, the B and C phase circuit breakers are closed, and the stable operation of the transformer is realized.

[0027] When the transformer is taken out of operation, the comprehensive command unit commands the three-phase circuit breaker (K) in the execution unit 4 to quickly open, and the comprehensive command unit uses the measuring PT2 and the measuring CT3 to measure the voltage and current signal changes in real time, calculates the residual magnetism of the transformer according to the measured voltage and current signals, and prepares for the next operation.

[0028] In general, the embodiment of the present application utilizes the precise phase control closing device and combines the residual magnetism calculation technology to realize zero inrush current operation of the no-load transformer. The precise phase control closing device comprises a measuring PT1, a measuring PT2, a measuring CT3, an execution unit 4 and a comprehensive command unit. When the transformer needs to be put into operation, the comprehensive command unit selects the ideal conduction closing time according to the residual magnetism data and the signal of the upper end measuring PT1 of the execution unit 4 to control the execution unit 4 to close, and the transformer is put into operation without inrush current; when the transformer exits operation, the comprehensive command unit calculates the residual magnetism of the transformer according to the signals of the lower end measuring PT2 and the measuring CT3 of the execution unit to prepare for the next operation.

[0029] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A precision phase control closing device for suppressing transformer inrush, comprising a measurement PT1, a measurement PT2, a measurement CT3, an execution unit (4) and a comprehensive command unit; characterized in that, The one end of the measuring PT1 is connected with the bus, and the other end is grounded. The incoming line end of the execution unit (4) is connected with the bus, and the outgoing line end of the execution unit (4) is connected in series with the high-voltage end of the measuring PT2, and the low-voltage end of the measuring PT2 is grounded. The incoming line end of the measuring CT3 is connected in series with the outgoing line end of the execution unit (4), and the outgoing line end of the measuring CT3 is the outgoing line end of the device. The integrated command unit uses the measuring PT1 to monitor the voltage signal of the power supply side in real time, and selects the command to the execution unit (4) according to the voltage signal when the transformer needs to be put into operation. When the transformer is out of operation, the integrated command unit executes the opening command according to the circuit breaker in the execution unit (4), and calculates the residual magnetism of the transformer core according to the voltage and current signals of the load side detected by the measuring PT2 and the measuring CT3, so as to prepare for the next transformer closing operation. The execution unit (4) comprises an A-phase circuit breaker, a B-phase bidirectional thyristor connected in parallel with a B-phase circuit breaker, and a C-phase bidirectional thyristor connected in parallel with a C-phase circuit breaker. The execution unit (4) is executed with the following time sequence closing command: first, control the A-phase circuit breaker to close; second, after a time delay, accurately control the B-phase bidirectional thyristor to conduct, and then accurately control the C-phase bidirectional thyristor to conduct; third, in the process of continuously conducting the B-phase bidirectional thyristor and the C-phase bidirectional thyristor, control the B-phase circuit breaker and the C-phase circuit breaker to close.

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