CN116013710A - Switch device with closing resistor for inhibiting excitation inrush current of transformer and use method - Google Patents

Abstract

The invention relates to a switch device with a closing resistor and a use method thereof for inhibiting excitation surge current of a transformer, which comprises a closing resistor tank body and a switch device tank body, wherein a closing resistor unit is arranged in the closing resistor tank body, two ends of the closing resistor unit are respectively connected with two sleeves in an assembling way through a connecting bus, a fixed contact component and a moving contact component are arranged in the switch device tank body, the fixed contact component and the moving contact component are respectively connected with two ends of the closing resistor unit, the switch device also comprises an operating mechanism for driving the moving contact component to stretch and retract to realize opening and closing, a current transformer for detecting the excitation surge current is arranged outside the connecting bus, and the operating mechanism adjusts closing speeds of the moving contact and the fixed contact according to the excitation surge current detected by the current transformer.

Description

Switching device with closing resistor for suppressing transformer excitation inrush current and using method

technical field

The invention relates to the field of electrical switches, in particular to a switching device with closing resistance for suppressing transformer excitation inrush current and a use method thereof.

Background technique

The transformer is the hub connecting the power grid and users, and it is indispensable in the power system, and its operating status also affects the stable operation of the power system. When the transformer is closed with no load, due to the randomness of the closing time, the iron core of the transformer will often be saturated, and because the core material has nonlinear characteristics, an exciting inrush current will be generated, and the magnitude of the exciting inrush current can reach ten times rated current.

The transformer excitation inrush current will cause the transformer differential protection to fail to operate correctly, causing the transformer to not work normally, and the excitation inrush current is too large, which will damage the circuit breaker and other electrical components connected to the transformer, resulting in large-area power grid stagnation and great losses. Stable operation has a very large impact. Therefore, it is very necessary to suppress the transformer excitation inrush current, which can greatly reduce unnecessary power outage accidents and power outage range. At present, the effects of existing suppression technologies are generally not ideal, and the use of open equipment will occupy a very large area, and the control accuracy of millisecond level cannot be achieved.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a switching device with closing resistance for suppressing transformer excitation inrush current and a use method.

The present invention is achieved through the following technical scheme, providing a switching device with a closing resistor for suppressing transformer excitation inrush current, including a closing resistor tank and a switch device tank, and a closing resistor unit is installed in the closing resistor tank , the two ends of the closing resistance unit are respectively assembled and connected to the two bushings through the connecting busbar. The switchgear tank is equipped with a static contact assembly and a moving contact assembly, and the static contact assembly and the moving contact assembly are respectively It is connected to both ends of the closing resistance unit, and also includes an operating mechanism that drives the moving contact assembly to expand and contract to realize opening and closing. The magnitude of the exciting inrush current adjusts the closing speed of the static contact assembly and the moving contact assembly.

In this scheme, when the current flows into the parallel switchgear with closing resistor from one end of the bushing assembly, the dynamic and static contacts of the switchgear unit are in the opening state at the beginning, and the circuit of the switchgear unit is in the open circuit state at this time, so the current flow Through the circuit of the closing resistance unit, the resistance value of the closing resistance unit is at the level of 1000 ohms, so the excitation inrush energy will be converted into resistance heating; when the moving contact in the switching device unit moves to connect with the static contact, at this time the switching device The unit realizes closing, and the circuit of the switching device unit changes from open circuit to open circuit. Because the circuit resistance of the switching device circuit is much smaller than that of the closing resistance circuit, the circuit of the closing resistance unit will be short-circuited by the circuit of the switching device unit, so that it can be realized The current passes through the circuit of the switching device unit and no longer flows through the circuit of the closing resistance unit. Because the resistance value of the circuit of the switching device is at the milliohm level, the heat generated is very small, which meets the flow requirements of the rated current after the excitation inrush current disappears.

The closing time of the switching device should not be less than the duration of the excitation inrush current to ensure that the excitation inrush current passes through the closing unit. After the excitation inrush current disappears, the circuit of the closing device is closed and the current flows through the closing device.

As an optimization, the operating mechanism includes a drive cylinder, a high-pressure cylinder, a high-pressure cylinder piston installed in the high-pressure cylinder, and a disc spring that pushes the high-pressure cylinder piston into the high-pressure cylinder to form a high-pressure oil chamber, and a piston rod that drives the cylinder. The high-pressure oil chamber is connected with the rod chamber of the drive cylinder, and also includes a reversing valve, a low-pressure oil chamber and an oil pump for pumping the oil in the low-pressure oil chamber into the high-pressure oil chamber. The low-pressure oil chamber, the high-pressure oil chamber and the rodless chamber of the drive cylinder are respectively connected with the reversing valve. The closing speed regulating valve is installed on the oil pipe of the low pressure oil chamber, and the opening speed regulating valve is installed on the oil pipe of the rodless chamber of the driving cylinder.

As an optimization, the disc spring is sleeved on the drive cylinder, and a disc spring push plate is arranged between the disc spring and the piston of the high-pressure cylinder. In this scheme, the disc spring cover plays a guiding role on the driving cylinder, and the disc spring push plate realizes that the thrust of the disc spring acts on the high-pressure cylinder piston.

As an optimization, the moving contact assembly includes a moving side connection seat connected to one end of the closing resistance unit and a moving main contact slidingly connected in the moving side connecting seat, and the static contact assembly includes another connection with the closing resistance unit. The static side connection seat connected at one end and the static main contact fixedly connected to the static side connection seat, the static arc contact is installed in the static main contact. In this solution, the moving main contact is inserted into the static main contact and wraps the static arc contact, so that the static arc contact can play the role of arc ignition while the connection is realized.

As an optimization, the moving contact shield is installed on the moving side connection seat, and the static contact shield is installed on the static side connection seat. The moving contact shield and the static contact shield in this scheme play a shielding role

As an optimization, the closing resistor tank is connected to the switchgear tank and separated by two pot insulators, the static contact assembly and the moving contact assembly are respectively connected to both ends of the closing resistance unit through connecting conductors, the The connecting conductor passes through the pot insulator and the passing place is airtightly arranged. In this scheme, the pot insulator realizes the sealed separation of the closing resistor tank and the switchgear tank.

A method for using a switching device with a closing resistor for suppressing transformer excitation inrush current includes the following steps:

a. Energy storage: the oil pump pumps the oil in the low-pressure oil chamber into the high-pressure oil chamber, pushes the piston of the high-pressure cylinder to move to compress the disc spring, and fills the high-pressure oil chamber with high-pressure oil;

b. Closing: Adjust the reversing valve so that the high-pressure oil chamber communicates with the rodless chamber of the oil cylinder. Since the high-pressure oil chamber communicates with the rod chamber of the drive cylinder, and the areas at both ends of the cylinder piston of the drive cylinder are different, the drive cylinder is pushed The piston rod is stretched out, and the moving contact assembly and the static contact assembly are connected through the insulating pull rod to realize closing; adjusting the size of the closing speed control valve can control the flow rate of the oil circuit to control the closing speed;

c. When closing the switch, it is necessary to make the closing time meet the flow requirements of the excitation current, that is, the switching device unit cannot be closed within the time that the excitation current passes. After the excitation current disappears, the switching device unit should be closed quickly to avoid the closing resistance unit Long-term flow of current causes overheating of the resistor sheet;

d. Opening: Adjust the reversing valve so that the low-pressure oil chamber communicates with the rodless chamber of the oil cylinder. The high-pressure oil will drive the cylinder piston to move to open the gate. Gate speed.

The beneficial effects of the present invention are as follows: the switching device with closing resistor for suppressing transformer excitation inrush current of the present invention and its use method, the switching device adopts a linear transmission structure, eliminating the need for intermediate link transmission, so that the contact closing time can reach the millisecond level, The switching device is precisely controlled and the transmission is stable, which can not only achieve the purpose of suppressing the inrush current of the transformer, but also accurately control the input time of the closing resistor to prevent the heat capacity of the closing resistor from exceeding the tolerance value of the closing resistor due to the long input time. The closing speed of the static contact assembly and the moving contact assembly can be adjusted according to the magnitude of the excitation inrush current detected by the current transformer.

The device uses SF6 insulating gas, which greatly reduces the insulation distance of the equipment, reduces the volume of the equipment, reduces the floor area of the equipment, and reduces equipment investment.

Description of drawings

Fig. 1 is a schematic diagram of the installation structure of the present invention;

Fig. 2 is a schematic diagram of the internal structure of direction A in Fig. 1 of the present invention;

Fig. 3 is a schematic structural diagram of the moving contact assembly of the present invention;

Fig. 4 is a schematic structural diagram of the static contact assembly of the present invention;

Fig. 5 is a schematic diagram of the operating mechanism of state 1 of the present invention;

Fig. 6 is a schematic diagram of the operating mechanism of state 2 of the present invention;

Fig. 7 is a schematic diagram of the operating mechanism of state 3 of the present invention;

Fig. 8 is a structural principle diagram of the present invention;

As shown in the figure:

1. Bushing assembly, 2. Connecting busbar, 3. Closing resistance tank, 4. Closing resistance unit, 5. Connecting conductor, 6. Switching device tank, 7. Static contact assembly, 71. Static side connection Seat, 72, static contact shield, 73, static main contact, 74, static arc contact, 8, moving contact assembly, 81, moving contact shield, 82, support plate, 83, moving side connecting seat , 84. Moving main contact, 85. Watch strap contact finger, 86. Guide ring, 9. Connecting rod, 10. Insulation rod, 11. Iron rod, 12. Operating mechanism, 13. Basin insulator, 14. Operating mechanism Housing, 15, drive oil cylinder, 16, oil cylinder piston, 17, piston rod, 18, disc spring, 19, disc spring push plate, 20, high pressure cylinder body, 21, high pressure cylinder piston, 22, low pressure oil chamber, 23, Reversing valve, 24, opening speed regulating valve, 25, closing speed regulating valve, 26, high pressure oil chamber.

Detailed ways

In order to clearly illustrate the technical features of the solution, the solution will be described below through specific implementation modes.

As shown in Figures 1 to 8, the switching device with closing resistor for suppressing transformer excitation inrush current of the present invention includes a closing resistor tank body 3 and a switching device tank body 6, and the closing resistor tank body 3 is equipped with a switching resistor Unit 4, both ends of the closing resistor unit 4 are respectively connected to two bushing assemblies 1 through connecting busbars 2, and the closing resistor tank body 3 and the switchgear tank body 6 are arranged side by side between the two connecting busbars 2.

The switchgear tank body 6 is equipped with a static contact assembly 7 and a moving contact assembly 8 , and the static contact assembly 7 and the moving contact assembly 8 are respectively connected to both ends of the closing resistance unit 4 . The closing resistor tank body 3 is connected to the switchgear tank body 6 and separated by two pot insulators 13, and the static contact assembly 7 and the moving contact assembly 8 are respectively connected to the two ends of the closing resistor unit 4 through the connecting conductor 5. connection, the connecting conductor 5 passes through the pot insulator 13 and the passing place is airtightly arranged.

The moving contact assembly 8 includes a moving side connecting seat 83 connected to one end of the closing resistance unit 4 and a moving main contact 84 slidingly connected in the moving side connecting seat 83 , the end of the moving main contact 84 is connected to the connecting rod 9 The insulating pull rod 10 is connected, one end of the iron pull rod 11 is connected with the insulating pull rod 10, the other end of the iron pull rod 11 is connected with the operating mechanism 12, and the outer side of the moving main contact 84 is connected with the moving side connecting seat 83 through the strap contact finger 85, and the moving side is connected The seat 83 is connected to the pot insulator 13 via the connecting conductor 5 . A guide ring 86 is installed between the moving main contact 84 and the moving side connecting seat 83 .

A moving contact shield 81 is installed on the moving side connecting seat 83, and a support plate 82 is installed inside the moving contact shield 81. When the gate is opened, the moving main contact 84 of the switching device is shrunk inside the moving contact shield 81, At this time, the switching device is opened, the circuit of the switching device is disconnected, and the circuit of the closing resistor unit is connected.

The static contact assembly 7 includes a static side connection seat 71 connected to the other end of the closing resistance unit 4 and a static main contact 73 fixedly connected to the static side connection seat 71. The static main contact 73 is equipped with a static Arc contact 74. The static-side connecting seat 71 is connected to the pot insulator 13 through the connecting conductor 5 .

A static contact shield 72 is mounted on the static side connecting seat 71 . The static main contact 73 is located inside the static contact shield 72 .

It also includes an operating mechanism 12 that drives the moving contact assembly 8 to expand and contract to realize opening and closing. The operating mechanism 12 is installed at one end of the switchgear tank 6 to drive the moving contact assembly 8 to realize opening and closing, thereby realizing the switchgear On and off of the circuit.

A current transformer for detecting inrush current is installed on the outside of the connecting bus 2, and the operating mechanism 12 adjusts the closing speed of the static contact assembly 7 and the moving contact assembly 8 according to the magnitude of the excitation inrush current detected by the current transformer.

When the current flows from one end of the bushing assembly into the parallel switchgear with closing resistor, the dynamic and static contacts of the switchgear unit are in the opening state at first, and the circuit of the switchgear unit is in the open circuit state at this time, so the current flows through the closing In the circuit of the resistance unit, the resistance value of the closing resistance unit is at the level of 1,000 ohms, so the energy of the inrush current will be converted into resistance heating; when the moving contact in the switch unit moves to connect with the static contact, the switch unit is closed The circuit of the switching device unit changes from open circuit to open circuit, because the circuit resistance of the switching device circuit is much smaller than that of the closing resistance circuit, so the closing resistance unit circuit will be short-circuited by the switching device unit circuit, so that the current can pass through the switch The circuit of the device unit does not flow through the circuit of the closing resistor unit. Because the resistance value of the switch device circuit is at the milliohm level, the heat generated is very small, which meets the flow requirements of the rated current after the excitation inrush current disappears.

When closing the switch, it is necessary to make the closing time meet the flow requirements of the excitation current, that is, the switch device unit cannot be closed within the time the excitation current passes through, and the switch device unit should be closed quickly after the excitation current disappears to avoid the closing resistance unit for a long time Passing current causes the resistor strip to overheat.

The operating mechanism 12 includes a drive cylinder 15, a high-pressure cylinder 20, a high-pressure cylinder piston 21 installed in the high-pressure cylinder 20, and a disc spring 18 that pushes the high-pressure cylinder piston 21 into the high-pressure cylinder 20 to form a high-pressure oil chamber 26 .

The high-pressure cylinder body 20 is fixed on the outside of the drive cylinder 15, and the disc spring 18 is sleeved on the drive cylinder 15. A disc spring push plate 19 is arranged between the disc spring 18 and the high-pressure cylinder piston 21, and the disc spring push plate 19 pushes the high pressure Cylinder piston 21.

The piston rod 17 of the driving oil cylinder 15 is connected with the moving contact assembly 8 through the insulating pull rod 10, and the high-pressure oil chamber 26 communicates with the rod chamber of the driving oil cylinder 15, and also includes a reversing valve 23, a low-pressure oil chamber 22 and a low-pressure oil chamber. The oil in the chamber 22 is pumped into the oil pump of the high-pressure oil chamber 26. The low-pressure oil chamber 22, the high-pressure oil chamber 26 and the rodless chamber of the drive cylinder 15 are connected with the reversing valve 23 respectively, and the oil pipe of the low-pressure oil chamber 22 is equipped with a closing Speed regulating valve 25, the oil pipe of drive oil cylinder 15 rodless chambers is equipped with sub-brake speed regulating valve 24.

It also includes an operating mechanism housing 14 , and each part in the operating mechanism 12 is installed in the operating mechanism housing 14 .

The closing resistor tank body 3 and the switchgear tank body 6 are equipped with SF6 as an insulating medium, which greatly reduces the space required to meet the insulation requirements, saves construction area and reduces equipment investment.

A method for using a switching device with a closing resistor for suppressing transformer excitation inrush current includes the following steps:

a. Energy storage: the oil pump pumps the oil in the low-pressure oil chamber 22 into the high-pressure oil chamber 26, and pushes the high-pressure cylinder piston 21 to move to compress the disc spring 18, so that the high-pressure oil chamber 26 is filled with high-pressure oil, as shown in Figure 5, black in the figure Part is high-pressure oil, and the grid part is low-pressure oil;

b. Closing: adjust the reversing valve 23 so that the high-pressure oil chamber 26 communicates with the rodless chamber of the oil cylinder 15. Since the high-pressure oil chamber 26 communicates with the rod chamber of the drive cylinder 15, and the two ends of the cylinder piston 16 of the drive cylinder 15 The areas are different, so the piston rod 17 of the driving cylinder 15 is pushed out, and the moving contact assembly 8 and the static contact assembly 7 are connected through the insulating pull rod 10 to realize closing; adjusting the size of the closing speed regulating valve 25 can control the oil circuit The flow rate controls the closing speed, as shown in Figure 6, the black part in the figure is high-pressure oil, and the grid part is low-pressure oil;

c. When closing the switch, it is necessary to make the closing time meet the flow requirements of the excitation current, that is, the switching device unit cannot be closed within the time that the excitation current passes. After the excitation current disappears, the switching device unit should be closed quickly to avoid the closing resistance unit Current flowing for a long time causes the resistor to overheat, as shown in Figure 7, the black part in the figure is high-pressure oil, and the grid part is low-pressure oil;

d. Opening: adjust the reversing valve 23 so that the low-pressure oil chamber 22 communicates with the rodless chamber of the oil cylinder 15, and the high-pressure oil will drive the movement of the cylinder piston 16 to realize the opening. Adjusting the size of the opening speed regulating valve 24 can control the oil circuit The size of the flow controls the opening speed.

Of course, the above description is not limited to the above examples, and the undescribed technical features of the present invention can be realized by or using existing technologies, and will not be repeated here; the above embodiments and drawings are only used to illustrate that the technical solutions of the present invention are not is a limitation of the present invention, and the present invention has been described in detail with reference to preferred embodiments, and those of ordinary skill in the art should understand that changes, modifications, Neither addition nor replacement deviates from the gist of the present invention, and should also belong to the protection scope of the claims of the present invention.

Claims (7)

1. A switch device with closing resistor for inhibiting excitation surge of a transformer is characterized in that: including closing resistor jar body (3) and switching device jar body (6), closing resistor unit (4) are equipped with in closing resistor jar body (3), the both ends of closing resistor unit (4) are connected with two sleeve pipe assemblies (1) through connecting busbar (2) respectively, be equipped with stationary contact subassembly (7) and moving contact subassembly (8) in switching device jar body (6), stationary contact subassembly (7) and moving contact subassembly (8) are connected with the both ends of closing resistor unit (4) respectively, still include actuating mechanism (12) that drive moving contact subassembly (8) are flexible to realize the divide-shut brake, the current transformer that detects excitation surge current is equipped with in the connecting busbar (2) outside, actuating mechanism (12) adjust the closing velocity of stationary contact subassembly (7) and moving contact subassembly (8) according to the excitation surge current size that current transformer detected.

2. The switching device with closing resistor for suppressing a magnetizing inrush current of a transformer of claim 1, characterized in that: the operating mechanism (12) comprises a driving oil cylinder (15), a high-pressure cylinder body (20), a high-pressure cylinder piston (21) arranged in the high-pressure cylinder body (20) and a disc spring (18) pushing the high-pressure cylinder piston (21) into the high-pressure cylinder body (20) to form a high-pressure oil cavity (26), a piston rod (17) of the driving oil cylinder (15) is connected with a moving contact assembly (8) through an insulating pull rod (10), the high-pressure oil cavity (26) is communicated with a rod cavity of the driving oil cylinder (15), the operating mechanism further comprises a reversing valve (23), a low-pressure oil cavity (22) and an oil pump pumping oil in the low-pressure oil cavity (22) into the high-pressure oil cavity (26), a rodless cavity of the low-pressure oil cavity (22), the high-pressure oil cavity (26) and a brake-closing speed regulating valve (25) are respectively arranged on an oil pipe of the low-pressure oil cavity (22), and a brake-separating speed regulating valve (24) is arranged on an oil pipe of the rodless cavity of the driving oil cylinder (15).

3. The switching device with closing resistor for suppressing a magnetizing inrush current of a transformer of claim 2, characterized in that: the disc spring (18) is sleeved on the driving oil cylinder (15), and a disc spring push plate (19) is arranged between the disc spring (18) and the high-pressure cylinder piston (21).

4. The switching device with closing resistor for suppressing a magnetizing inrush current of a transformer of claim 2, characterized in that: the movable contact assembly (8) comprises a movable side connecting seat (83) connected with one end of the closing resistor unit (4) and a movable main contact (84) connected in the movable side connecting seat (83) in a sliding mode, the fixed contact assembly (7) comprises a fixed side connecting seat (71) connected with the other end of the closing resistor unit (4) and a fixed main contact (73) fixedly connected to the fixed side connecting seat (71), and a static arc contact (74) is arranged in the fixed main contact (73).

5. The switching device with closing resistor for suppressing a magnetizing inrush current of a transformer of claim 4, characterized by: the movable contact shielding cover (81) is arranged on the movable side connecting seat (83), and the fixed contact shielding cover (72) is arranged on the fixed side connecting seat (71).

6. The switching device with closing resistor for suppressing a magnetizing inrush current of a transformer of claim 4, characterized by: the switching-on resistor tank body (3) is connected with the switching device tank body (6) and is separated through two basin-type insulators (13), the fixed contact assembly (7) and the moving contact assembly (8) are connected with two ends of the switching-on resistor unit (4) through connecting conductors (5) respectively, and the connecting conductors (5) penetrate through the basin-type insulators (13) and pass through the sealing positions.

7. A method of using the switching device with closing resistor for suppressing a magnetizing inrush current of a transformer as claimed in claim 2, comprising the steps of:

a. and (3) energy storage: the oil pump pumps the oil in the low-pressure oil cavity (22) into the high-pressure oil cavity (26) to push the high-pressure cylinder piston (21) to move so as to compress the disc spring (18), so that the high-pressure oil cavity (26) is filled with high-pressure oil;

b. closing: the reversing valve (23) is regulated to enable the high-pressure oil cavity (26) to be communicated with the rodless cavity of the oil cylinder (15), and as the high-pressure oil cavity (26) is communicated with the rod cavity of the driving oil cylinder (15) and the areas of two ends of the oil cylinder piston (16) of the driving oil cylinder (15) are different, the piston rod (17) of the driving oil cylinder (15) is pushed to extend out, and the movable contact assembly (8) is communicated with the fixed contact assembly (7) through the insulating pull rod (10) to realize closing; the magnitude of the switching-on speed regulating valve (25) can be regulated to control the magnitude of the oil path flow so as to control the switching-on speed;

c. when the switching-on action is performed, the switching-on time needs to meet the current requirement of exciting current, namely the switching device unit cannot be switched on in the passing time of the exciting current, and after the exciting current disappears, the switching device unit is required to be switched on rapidly so as to avoid overheating of a resistor sheet caused by long-time current flowing through a switching-on resistor unit;

d. and (3) opening: the reversing valve (23) is regulated, so that the low-pressure oil cavity (22) is communicated with the rodless cavity of the oil cylinder (15), the high-pressure oil can drive the oil cylinder piston (16) to move to realize opening, and the opening speed regulating valve (24) is regulated to control the flow of an oil way so as to control the opening speed.

Images