Adjustable reactor for switch short circuit test and design method

Abstract

The invention relates to an adjustable reactor for a switch short circuit test and a design method, the adjustable reactor comprises a plurality of coil assemblies which are sequentially connected in series, each coil assembly comprises a rolled coil, coil interlayer positioning blocks are arranged on the upper side and the lower side of each rolled coil, and each rolled coil is formed by rolling a metal plate; a coil input end is formed at the end of the outer side of the metal plate, a coil output end is formed at the end of the inner side of the metal plate, a plurality of limiting partition blocks are arranged on the lower sides of the coil interlayer positioning blocks, each layer of the wound coil is arranged between every two corresponding limiting partition blocks, and the two ends of the coil interlayer positioning blocks corresponding up and down are tensioned and fixed through coil tensioning screw rods respectively. In every two adjacent coil assemblies, the coil output end of the input side coil assembly is connected with the coil input end of the output side coil assembly, and the coil input end and the coil output end in the same coil assembly are connected through a knife switch. The short-circuit dynamic thermal stability tolerance level can meet the test use requirement, and meanwhile the inductance adjustable function can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactors, and more specifically, to an adjustable reactor for switch short-circuit tests and a design method thereof. Background Art

[0002] According to relevant national standards, the short-circuit current test of tap-changers is a type test. When conducting a short-circuit current test on a tap-changer, it is necessary to limit the short-circuit current on the line and be able to adjust the inductance for tests of different tap-changers. This requires designing a reactor that can withstand short-circuit currents and has adjustable inductance. In addition, most of the reactors in the prior art adopt a pancake coil structure. For the adjustable reactor used in switch tests, the inductance requirement is small, less than 0.02 mH at the minimum, but the maximum short-circuit current peak can reach 170 kA. This places a high requirement on the dynamic and thermal stability tolerance level of the reactor product, and the existing reactors cannot meet the above requirements. Summary of the Invention

[0003] The purpose of the present invention is to provide an adjustable reactor for switch short-circuit tests and a design method thereof, whose short-circuit dynamic and thermal stability tolerance level can meet the requirements of test use, and at the same time can realize the function of adjustable inductance.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] An adjustable reactor for switch short-circuit tests includes a plurality of coil components connected in series in sequence. Each coil component includes a wound coil and a coil layer positioning block. The wound coil is formed by rolling a metal plate, and the outer end of the metal plate forms the coil input end, and the inner end of the metal plate forms the coil output end. One side of the coil layer positioning block is provided with a plurality of limiting partitions, and a coil layer limiting space is formed between adjacent limiting partitions. Each layer of the wound coil is arranged in the corresponding coil layer limiting space. Coil layer positioning blocks are provided on both the upper and lower sides of the wound coil, and the two ends of the upper and lower corresponding coil layer positioning blocks are tightened and fixed by corresponding coil tensioning screws respectively. In two adjacent coil components, the coil output end of the input-side coil component is connected to the coil input end of the output-side coil component through a coil connection plate, and the coil input end and the coil output end in the same coil component are connected through a knife switch.

[0006] The coil layer positioning blocks on both sides of the coil assembly are evenly distributed along the circumferential direction of the wound coil. Positioning plates are provided on both sides of the coil assembly, and the positioning plates are arranged outside the coil layer positioning blocks. The inner ends of the vertically corresponding coil layer positioning blocks are tightened and fixed by the inner coil tensioning screw, and the outer ends of the vertically corresponding coil layer positioning blocks are tightened and fixed by the outer coil tensioning screw. Both ends of the outer coil tensioning screw and both ends of the inner coil tensioning screw respectively pass through the corresponding positioning plates on both sides and are connected to the nut assembly.

[0007] The coil assemblies are stacked sequentially from top to bottom, and the positioning plates of each coil assembly are tightened and fixed by the overall tensioning screw located outside the wound coil. Support pads are provided between the adjacent positioning plates on the adjacent sides of the adjacent coil assemblies.

[0008] A control installation panel is provided on one side of the coil assembly, and a coil connection plate and a knife switch are arranged on the control installation panel. One side of the positioning plate is fixedly connected to the control installation panel.

[0009] The knife switch is provided with a switch frame, and support plates are provided on both sides of the switch frame and are respectively connected corresponding to the coil input end and the coil output end in the same coil assembly.

[0010] The coil input end of the uppermost coil assembly is connected to an input end plate, the coil output end of the lowermost coil assembly is connected to an output end plate, and a post insulator is provided below the lowermost coil assembly.

[0011] The coil output end of the coil assembly is in an L shape. The coil output end includes a vertical section and a horizontal section, and the horizontal section is parallel and aligned with the coil input end.

[0012] A design method for an adjustable reactor for switch short-circuit tests according to the above, includes determining the inductance calculation method:

[0013] Step 1.1: Determine the mutual inductance calculation method between two coils:

[0014] Regard the wound coil as a cylindrical structure, and the adjacent two coils are concentric coils. H1 and H2 respectively represent the respective heights of the two coils, R1 and R2 are the radii of the number of turns of the two coils, S is the center distance between the two coils. Establish a coordinate system with the center of the coil with height H1 as the origin, and take a ring with height z 1 and thickness dz 1 on the coil with height H1, and take a ring with height z 2 and thickness dz 2 on the coil with height H2. There is:

[0015]

[0016] In the above formula (1), M is the mutual inductance between the two coils, and n 1 , n 2 are the number of turns of the two coils, μ 0 is the magnetic permeability of vacuum, θ is the angle between the connecting line of the outer diameters of the two coils and the horizontal direction,

[0017] Let: Then there is:

[0018]

[0019] In the above formula (2):

[0020] z′ 1 = S + H 1 / 2 + H 2 / 2,

[0021] z′ 2 = S + H 1 / 2 - H 2 / 2,

[0022] z′ 3 = S - H 1 / 2 - H 2 / 2,

[0023] z′ 4 = S - H 1 / 2 + H 2 / 2;

[0024] Let: Then there is:

[0025]

[0026] In the above formula (3):

[0027]

[0028] In the above formula (4), z is any one of z 1 ′, z 2 ′, z 3 ′, z 4 ′;

[0029] Step 1.2: Determine the calculation method of the self-inductance of a single coil:

[0030] For the above formula (3), when R1 = R2 = R and S = 0, the two coils are regarded as one coil. At this time, the origin of the coordinate system is the center of the coil, the height of the coil H = H1 = H2, and the self-inductance L of the coil can be obtained from the above formula (3):

[0031]

[0032] In the above formula (5), C i (R, R, H) has the same meaning as in the above formula (4), where R1 = R2 = R, z = H after integration, and n is the number of turns of the coil.

[0033] A design method for an adjustable reactor for the switch short - circuit test described above includes determining the thermal stability calculation method under short - circuit current:

[0034] Calculate the time t for the short - circuit current stability value to pass through the wound coil according to the following formula (6):

[0035]

[0036] In the above formula (6), I d is the short - circuit current stability value passing through the wound coil, is the short - time thermal current, and its calculation is as follows:

[0037]

[0038] In the above formula (7), q is the cross - sectional area of a single metal sheet forming the wound coil, m is the number of parallel strands of the wound coil, K D is the additional loss coefficient of the wound coil, A is the maximum allowable overheat parameter of the wound coil, B is the overheat parameter of the wound coil at the start of the short - circuit, where:

[0039]

[0040]

[0041] In the above formula (8), θ k is the limit temperature of the wound coil (15), t 0 is the time elapsed after the start of the short - circuit, θ N is the temperature of the wound coil (15) at the start of the short - circuit, and lg is the logarithm symbol;

[0042] During design, when the time t for the short - circuit current stability value calculated according to the above formula (6) to pass through the winding is greater than the required value, it is determined that the design scheme meets the thermal stability requirements.

[0043] A design method for an adjustable reactor for the switch short - circuit test described above includes determining the dynamic stability calculation method under short - circuit current:

[0044] Assume that the maximum short - circuit current that the coil assembly can withstand is I y , and its calculation is as follows:

[0045]

[0046] In the above formula (9), α is the shape coefficient of the wound coil, h is the calculated height of the wound coil, m is the number of parallel strands of the wound coil, and F ng is the allowable force per turn of the wound coil per unit length, and its calculation is as follows:

[0047]

[0048] In the above formula (10), q is the cross-sectional area of the metal sheet forming the wound coil, σ is the allowable stress of the turn, E is the elastic modulus of the metal sheet, and l is the length of the outer turn of the wound coil between the positioning blocks of the two coil layers, and its calculation is as follows:

[0049]

[0050] In the above formula (11), D 2 is the diameter of the outer turn of the wound coil, l 1 is the width of the positioning block between the coil layers, and n is the number of positioning blocks between the coil layers;

[0051] During design, when the short-circuit current calculated according to the above formula (9) is greater than the required short-circuit current peak value, it is determined that the design scheme meets the dynamic stability requirements.

[0052] The advantages and positive effects of the present invention are as follows:

[0053] 1. The short-circuit dynamic and thermal stability tolerance level of the present invention can meet the test use requirements, and at the same time, the inductance adjustable function can be realized.

[0054] 2. Considering the short-circuit tolerance requirement in the structure of the present invention, metal sheets with different thicknesses are used to make the coil windings. At the same time, in order to reduce the mutual inductance influence between the coil components, the distance between the coil components is increased as much as possible through the support pads. And in order to enhance the overall short-circuit resistance ability, the support pads between the coil components can be made of epoxy glass cloth board with good weather resistance and strength. And in order to avoid the springback of the metal sheet during winding, the present invention uses the positioning blocks between the coil layers to position the positions of each layer of the wound coil, uses the upper and lower positioning plates and the coil tightening screws to clamp and position the wound coil. At the same time, each coil component is stacked in sequence along the height direction and tightened and positioned by the overall tightening screws, thereby ensuring the overall strength of the present invention.

[0055] 3. The present invention also needs to consider reactance adjustment. Therefore, the coil input end and the coil output end in the same coil component of the present invention are connected by a knife switch, and different coil components are connected to the circuit by opening and closing the knife switch, so as to achieve the purpose of inductance adjustment for the tests of different tap switches. And the present invention can not only realize the connection of a single coil component to the circuit, but also realize the series connection of multiple coil components, which also greatly increases the adjustment range of the present invention.

[0056] 4. Since the present invention adopts a series connection of multiple coil components, when calculating the inductance, it is necessary to consider both the self-inductance of the reactor coil and the mutual inductance between the coils. The design method of the present invention can accurately calculate the self-inductance and mutual inductance. In addition, the design method of the present invention ensures that the short-circuit dynamic and thermal stability tolerance level of the final product can meet the test use requirements through the calculation of dynamic and thermal stability under short-circuit large current. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is the front view of the present invention,

[0058] Figure 2 is Figure 1 the left view of the present invention in

[0059] Figure 3 is Figure 1 the top view of the present invention in

[0060] Figure 4 is Figure 1 the structural schematic diagram of a single coil component in

[0061] Figure 5 is Figure 4 the three-dimensional schematic diagram of the coil component in

[0062] Figure 6 is Figure 5 the structural schematic diagram of the wound coil in

[0063] Figure 7 is Figure 5 the structural schematic diagram of the coil layer positioning block in

[0064] Figure 8 is Figure 1 the schematic diagram of the circuit connection principle of the present invention in

[0065] Figure 9 is the analysis schematic diagram when the present invention calculates the inductance.

[0066] Among them, 1 is the first coil component, 2 is the second coil component, 3 is the third coil component, 4 is the fourth coil component, 5 is the input end plate, 6 is the support pad, 7 is the post insulator, 8 is the output end plate, 9 is the knife switch, 10 is the coil connection plate, 11 is the control installation panel, 12 is the switch rack, 13 is the positioning plate, 1301 is the overall tensioning screw, 14 is the coil layer positioning block, 1401 is the outer tensioning screw of the coil, 1402 is the inner tensioning screw of the coil, 1403 is the outer end hole of the positioning block, 1404 is the inner end hole of the positioning block, 1405 is the limit spacer, 15 is the wound coil, 1501 is the coil input end, and 1502 is the coil output end. DETAILED DESCRIPTION OF THE INVENTION

[0067] The present invention will be further described in detail below with reference to the accompanying drawings.

[0068] As Figures 1-9 shown, the present invention includes a plurality of coil components connected in series in sequence, and as Figures 4-7 shown, the coil component includes a wound coil 15 and an inter-layer positioning block 14 for the coil. Among them, the wound coil 15 is formed by winding a metal plate, and a coil input end 1501 is formed at the outer end of the metal plate, and a coil output end 1502 is formed at the inner end of the metal plate. In this embodiment, the metal plate is a copper plate. Compared with the prior art in which a copper wire is used to wind the coil, the present invention uses a copper plate to wind the coil, and the coil is prone to springback. Therefore, the present invention uses the inter-layer positioning block 14 for the coil to define the positions of the layers of the wound coil 15. As Figure 7 shown, a plurality of limiting spacers 1405 are provided on the lower side of the inter-layer positioning block 14 for the coil, and a coil layer limiting space is formed between adjacent limiting spacers 1405. As Figure 5 shown, each layer of the wound coil 15 is respectively arranged in the corresponding coil layer limiting space. Inter-layer positioning blocks 14 for the coil are provided on both the upper and lower sides of the wound coil 15, and the inner ends of the upper and lower corresponding inter-layer positioning blocks 14 for the coil are tightened and fixed by an inner coil tightening screw 1402, and the outer ends of the upper and lower corresponding inter-layer positioning blocks 14 for the coil are tightened and fixed by an outer coil tightening screw 1401. As Figure 5 shown, an inner end hole 1404 for the inner coil tightening screw 1402 to pass through is provided at the inner end of the inter-layer positioning block 14 for the coil, and an outer end hole 1403 for the outer coil tightening screw 1401 to pass through is provided at the outer end of the inter-layer positioning block 14 for the coil. And as Figure 1 shown, in adjacent two coil components, the coil output end 1502 of the input-side coil component is connected to the coil input end 1501 of the output-side coil component through a coil connection plate 10. In this embodiment, the coil connection plate 10 is made of a copper bar, and the coil input end 1501 and the coil output end 1502 in the same coil component are connected through a knife switch 9. When the present invention works, as Figure 1 and Figure 8As shown in the figure, taking the example of having four coil components and four knife switches 9 (K1, K2, K3, K4), when K1 is open and K2, K3, K4 are closed, the first coil component 1 is connected to the circuit. When K2 is open and K1, K3, K4 are closed, the second coil component 2 is connected to the circuit. When K3 is open and K1, K2, K4 are closed, the third coil group 3 is connected to the circuit. When K4 is open and K1, K2, K3 are closed, the fourth coil component 4 is connected to the circuit. In this way, different reactances can be connected to the circuit. When the short-circuit voltage of the circuit is constant, different short-circuit current inputs can be changed, thereby meeting the different short-circuit current requirements for different switches. In addition, the above method is only for a single coil component to be connected to the circuit. In this embodiment, the series connection of multiple coil components can also be realized. For example, when K1 and K2 are open and K3 and K4 are closed, both the first coil component 1 and the second coil component 2 are connected at this time, which greatly increases the adjustment range of the present invention. For example, 15 different reactances can be connected to the circuit in the above embodiment. Figure 1 and Figure 8 The A1, X1, A2, X2, A3, X3, A4, X4 terminals in

[0069] such as Figure 5 shown, in this embodiment, the coil layer positioning blocks 14 on both sides of the coil component are evenly distributed along the circumferential direction of the wound coil 15. As Figure 1 and Figure 4 shown, positioning plates 13 are provided on both sides of the coil component. And as Figure 4 shown, the positioning plates 13 are arranged outside the coil layer positioning blocks 14. The two ends of the outer coil tensioning screw 1401 and the two ends of the inner coil tensioning screw 1402 respectively pass through the corresponding positioning plates 13 on both sides and are connected to the nut components. In this way, the positioning plates 13 on both sides clamp and fix the coil layer positioning blocks 14 and the wound coil 15. In addition, as Figure 1 shown, the coil components are stacked and arranged in sequence from top to bottom. And as Figure 3 shown, the positioning plates 13 of each coil component are tensioned and fixed by the overall tensioning screw 1301 located outside the wound coil 15. In this way, the firm connection of each coil component is realized. And a support pad 6 is provided between the adjacent positioning plates 13 on the adjacent sides of the adjacent coil components to ensure that there is a sufficient distance between the adjacent coil components.

[0070] such as Figures 1-3 shown, a control installation panel 11 is provided on one side of the coil component. And the coil connecting plate 10 and the knife switch 9 are arranged on the control installation panel 11. As Figure 3 shown, one side of the positioning plate 13 is fixedly connected to the control installation panel 11.

[0071] such as Figure 1As shown, the knife switch 9 is provided with a switch frame 12, and both sides of the switch frame 12 are provided with support plates respectively connected to the coil input terminal 1501 and the coil output terminal 1502 in the same coil assembly. When the knife switch 9 is closed, the support plates on both sides are connected.

[0072] As Figures 1-2 shown, the coil input terminal 1501 of the uppermost coil assembly is connected to an input terminal plate 5, and the coil output terminal 1502 of the lowermost coil assembly is connected to an output terminal plate 8.

[0073] As Figure 1 shown, a post insulator 7 is provided below the lowermost coil assembly to realize the overall installation support of the present invention.

[0074] As Figures 4-5 shown, the coil output terminal 1502 of the coil assembly is in an L shape, which includes a vertical section and a horizontal section. The horizontal section is parallel and aligned with the coil input terminal 1501 for convenient connection.

[0075] As Figure 1 shown, one or more sets of wound coils 14 can be arranged along the height direction as needed in the coil assembly, where Figure 1 in an embodiment of the present invention shown, both the first coil assembly 1 and the second coil assembly 2 are provided with one set of wound coils 14, the third coil assembly 3 is provided with two sets of wound coils 14, and the fourth coil assembly 4 is provided with three sets of wound coils 14. The wound coils 14 in the same coil assembly 4 are also connected in series in sequence. In addition, the thickness of the metal sheet for making the wound coil 4 can also be selected and designed according to actual needs.

[0076] In the structural design of the present invention, on the one hand, the structural design of short-circuit withstand capacity needs to be considered. Since the inductance value of the present invention is very small and the number of coil turns is not much, in order to meet the short-circuit resistance requirements, the present invention can use copper plates with different thicknesses as windings. At the same time, in order to reduce the mutual inductance influence between coil assemblies, the distance between coil assemblies is increased as much as possible through the support pads 6. And in order to enhance the overall short-circuit resistance ability, the support pads 6 between coil assemblies can be made of epoxy glass cloth boards with good weather resistance and strength. On the other hand, the structural design of the adjustment method also needs to be considered in the present invention. As Figure 8 shown, the present invention realizes connecting different coil assemblies into the circuit by opening and closing the knife switch 9, and further realizes the inductance adjustment for the tests of different tap switches. In addition, detection sensors (such as distance sensors, angle sensors, etc.) can be provided on the knife switch 9 as needed to monitor its opening and closing state in real time. The detection sensors are well-known technologies in the art and are commercially available products.

[0077] Since the present invention uses a copper plate with better strength for coil winding to meet the requirement of withstanding short - circuit mechanical force, its calculation and analysis also need to be considered, including:

[0078] 1. Determine the inductance calculation method.

[0079] Step 1.1: Determine the mutual inductance calculation method between two coils.

[0080] Since the present invention realizes inductance adjustment by connecting multiple coil components in series, when calculating the inductance, both the self - inductance of the coils and the mutual inductance between the coils need to be considered. Since the mutual inductance is related to the magnetic field direction generated by the coils, when calculating the mutual inductance, the magnetic field directions of the coils need to be comprehensively considered at the same time, and the winding directions of the coils are reasonably designed.

[0081] Since the present invention uses a copper plate to wind and form the wound coil 15, the wound coil 15 can be regarded as a cylindrical structure, and as Figure 9 shown, two different coils are concentrically arranged. H1 and H2 respectively represent the respective heights of the two coils, R1 and R2 are the radii of the number of turns of the two coils, S is the center distance between the two coils. Taking the center of the coil with height H1 as the origin to establish a coordinate system, and taking a ring with height z 1 and thickness dz 1 on the coil with height H1, and taking a ring with height z 2 and thickness dz 2 on the coil with height H2, there is:

[0082]

[0083] In the above formula (1), M is the mutual inductance between the two coils, n 1 and n 2 are the number of turns of the two coils, μ 0 is the vacuum permeability, θ is the included angle between the connection line of the outer diameters of the two finite - length and infinitely - thin coils and the horizontal direction,

[0084] Let: Then there is:

[0085]

[0086] In the above formula (2):

[0087] z′ 1 =S + H 1 / 2 + H 2 / 2,

[0088] z′ 2 =S + H 1 / 2H 2 / 2,

[0089] z' 3 = S - H 1 / 2 - H 2 / 2,

[0090] z' 4 = S - H 1 / 2 + H 2 / 2;

[0091] Let: Then there is:

[0092]

[0093] In the above formula (3):

[0094]

[0095] In the above formula (4), z is any value among z 1 ', z 2 ', z 3 ', z 4 '.

[0096] Step 1.2: Determine the calculation method of the self - inductance of a single coil.

[0097] For the above formula (3), when R1 = R2 = R and S = 0, as Figure 9 shown, it can be regarded as a single coil. At this time, the origin of the coordinate system is the center of the coil, and the height of the coil H = H1 = H2. In this case, there is a situation where z = 0. At this time, it is equivalent to calculating the self - inductance L of the coil. From the above formula (3), we can get:

[0098]

[0099] In the above formula (5), C i (R, R, H) has the same meaning as in the above formula (4), where R1 = R2 = R, after integration z = H, and n is the number of turns of the coil.

[0100] II. Determine the calculation method of dynamic and thermal stability under short - circuit large current.

[0101] Generally, for a 500kV large - capacity current - limiting reactor connected in series in the system, the effective value of the short - circuit current it withstands is about 15 - 30kA, and the peak value of the short - circuit current is about 37.5 - 75kA. However, the reactor of the present invention is used for switch short - circuit tests, and the short - circuit current it withstands is more severe. The maximum effective value of the short - circuit current is 62kA, and the maximum peak value is 167kA. Therefore, it is very necessary to study and calculate the dynamic and thermal stability of the product of the present invention under short - circuit conditions.

[0102] 2.1: Determine the calculation method of thermal stability under short - circuit current.

[0103] When a short - circuit current passes through the reactor of the present invention, due to the large current value, it will cause the heating of the windings of the coil assembly instantaneously, and the heat is proportional to the square of the current. Therefore, it is necessary to stably control the time for the stable value of the short - circuit current to pass through the windings.

[0104] The present invention calculates the time t for the stable value of the short - circuit current to pass through the wound coil 15 according to the following formula:

[0105]

[0106] In the above formula (6), I d is the stable value of the short - circuit current passing through the wound coil 15, is the short - time thermal current, and its calculation is as follows:

[0107]

[0108] In the above formula (7), q is the cross - sectional area of a single metal sheet (copper sheet) forming the wound coil 15, m is the number of parallel windings of the wound coil 15, K D is the additional loss coefficient of the wound coil 15, A is the maximum allowable overheat parameter of the wound coil 15, B is the overheat parameter of the wound coil 15 at the start of the short - circuit, where:

[0109]

[0110]

[0111] In the above formula (8), θ k is the limiting temperature of the wound coil 15, t 0 is the time elapsed after the start of the short - circuit, θ N is the temperature of the wound coil 15 at the start of the short - circuit, and lg is the logarithm symbol.

[0112] When designing the present invention, when the time t for the stable value of the short - circuit current calculated according to the above formula (6) to pass through the windings is greater than the required value, it can be determined that the scheme meets the thermal stability requirements.

[0113] 2.2: Determine the dynamic stability calculation method under short - circuit current.

[0114] When the reactor withstands a short-circuit current, under the action of the magnetic field, the wound coil 15 of the winding is subjected to the short-circuit electrodynamic force. The short-circuit electrodynamic force will increase the magnetic flux enclosed by the loop and the loop inductance, and the inductance of the reactor increases with the increase of the diameter of the wound coil 15 and the decrease of the cross-sectional area. Therefore, the force acting on the reactor coil assembly is to axially compress the wound coil 15 in each coil assembly, and the force in the diameter direction of the wound coil 15 is to stretch the wound coil 15. So, the regulating reactor winding for short-circuit tests should have sufficient short-circuit resistance, that is, when the wound coil 15 withstands the maximum short-circuit impact capacity, it should not be damaged or have residual deformation.

[0115] Assume that the maximum short-circuit current that the reactor coil winding can withstand is I y , and its calculation is as follows:

[0116]

[0117] In the above formula (9), α is the shape coefficient of the wound coil 15, h is the calculated height of the wound coil 15, m is the number of parallel turns of the wound coil 15, and F ng is the force allowed per unit length of the turns of the wound coil 15, and its calculation is as follows:

[0118]

[0119] In the above formula (10), q is the cross-sectional area of the metal sheet forming the wound coil 15, σ is the allowable stress of the turns, E is the elastic modulus of the metal sheet, and l is the length of the outer turns of the wound coil 15 between the positioning blocks 14 of two coil layers, and its calculation is as follows:

[0120]

[0121] In the above formula (11), D 2 is the diameter of the outer turns of the wound coil 15, l 1 is the width of the positioning block 14 between coil layers, and n is the number of positioning blocks 14 between coil layers.

[0122] When designing the present invention, when the short-circuit current calculated according to the above formula (9) is greater than the required short-circuit current peak value, it can be determined that this scheme meets the dynamic stability requirements.

[0123] The above various formulas of the present invention are derived from "Reactor Theory and Calculation".

Claims

1. An adjustable reactor for switch short - circuit test, Characterized in that: It includes a plurality of coil components connected in series in sequence. The coil component includes a wound coil (15) and a coil inter - layer positioning block (14). The wound coil (15) is formed by winding a metal plate. And the outer end of the metal plate forms a coil input end (1501), the inner end of the metal plate forms a coil output end (1502). One side of the coil inter - layer positioning block (14) is provided with a plurality of limiting partitions (1405), and a coil layer limiting space is formed between adjacent limiting partitions (1405). Each layer of the wound coil (15) is respectively arranged in the corresponding coil layer limiting space. Coil inter - layer positioning blocks (14) are provided on both the upper and lower sides of the wound coil (15), and the two ends of the upper and lower corresponding coil inter - layer positioning blocks (14) are respectively tightened and fixed by corresponding coil tensioning screws. In two adjacent coil components, the coil output end (1502) of the input - side coil component is connected to the coil input end (1501) of the output - side coil component through a coil connecting plate (10), and the coil input end (1501) and the coil output end (1502) in the same coil component are connected through a knife - switch (9).

2. The adjustable reactor for switch short - circuit test according to claim 1, Characterized in that: The coil inter - layer positioning blocks (14) on both sides of the coil component are evenly distributed along the circumferential direction of the wound coil (15). Positioning plates (13) are provided on both sides of the coil component, and the positioning plates (13) are arranged outside the coil inter - layer positioning blocks (14). The inner ends of the upper and lower corresponding coil inter - layer positioning blocks (14) are tightened and fixed by coil inner tensioning screws (1402), and the outer ends of the upper and lower corresponding coil inter - layer positioning blocks (14) are tightened and fixed by coil outer tensioning screws (1401). And the two ends of the coil outer tensioning screw (1401) and the two ends of the coil inner tensioning screw (1402) respectively pass through the corresponding positioning plates (13) on the corresponding side and are connected to nut assemblies.

3. The adjustable reactor for switch short - circuit test according to claim 2, Characterized in that: Each coil component is stacked and arranged in sequence from top to bottom, and the positioning plates (13) of each coil component are tightened and fixed by an overall tensioning screw (1301) located outside the wound coil (15). Support pads (6) are provided between the adjacent side positioning plates (13) of adjacent coil components.

4. The adjustable reactor for switch short - circuit test according to claim 2, Characterized in that: A control installation panel (11) is provided on one side of the coil component, and the coil connecting plate (10) and the knife - switch (9) are arranged on the control installation panel (11). One side of the positioning plate (13) is fixedly connected to the control installation panel (11).

5. The adjustable reactor for switch short - circuit test according to claim 1, Characterized in that: The knife switch (9) is provided with a switch frame (12), and support plates are arranged on both sides of the switch frame (12) and are respectively connected corresponding to a coil input end (1501) and a coil output end (1502) in the same coil assembly.

6. The adjustable reactor for switch short-circuit test according to claim 1, characterized in that: The coil input end (1501) of the uppermost coil assembly is connected to an input end plate (5), the coil output end (1502) of the lowermost coil assembly is connected to an output end plate (8), and a post insulator (7) is arranged below the lowermost coil assembly.

7. The adjustable reactor for switch short-circuit test according to claim 1, characterized in that: The coil output end (1502) of the coil assembly is in an L shape, the coil output end (1502) includes a vertical section and a horizontal section, and the horizontal section is parallel and aligned with the coil input end (1501).

8. A design method of the adjustable reactor for switch short-circuit test according to claim 1, characterized in that: including determining the inductance calculation method: Step 1.1: Determine the mutual inductance calculation method between two coils: Regarding the wound coil (15) as a cylindrical structure, and the adjacent two coils as concentric coils, where H1 and H2 respectively represent the heights of the two coils, R1 and R2 are the radii of the number of turns of the two coils, and S is the center distance between the two coils. A coordinate system is established with the center of the coil with height H1 as the origin, and a ring with height z 1 and thickness dz 1 is taken on the coil with height H1. A ring with height z 2 and thickness dz 2 is taken on the coil with height H2. Then there is: In the above formula (1), M is the mutual inductance between the two coils, n 1 , n 2 are the number of turns of the two coils, μ 0 is the magnetic permeability of vacuum, θ is the angle between the line connecting the outer diameters of the two coils and the horizontal direction, Let: Then: In the above formula (2): z′ 1 = S + H 1 / 2 + H 2 / 2 z′ 2 = S + H 1 / 2 - H 2 / 2 z′ 3 = S - H 1 / 2 - H 2 / 2 z′ 4 = S - H 1 / 2 + H 2 / 2; Let: Then there is: In the above formula (3): In the above formula (4), z is any value among z 1 ′, z 2 ′, z 3 ′, z 4 ′; Step 1.2: Determine the self-inductance calculation method of a single coil: For the above formula (3), when R1 = R2 = R and S = 0, the two coils are regarded as one coil. At this time, the origin of the coordinate system is the center of the coil, the height H of the coil = H1 = H2, and the self-inductance L of the coil can be obtained from the above formula (3): In the above formula (5), C i (R, R, H) has the same meaning as in the above formula (4), where R1 = R2 = R, z = H after integration, and n is the number of turns of the coil.

9. A design method of the adjustable reactor for switch short-circuit test according to claim 1, characterized in that: including determining the thermal stability calculation method under short-circuit current: Calculate the time t for the short-circuit current steady value to pass through the wound coil (15) according to the following formula (6): In the above formula (6), I d is the stable value of the short-circuit current passing through the wound coil (15), is the short-time thermal current, and its calculation is as follows: In the above formula (7), q is the cross-sectional area of a single metal sheet forming the wound coil (15), m is the number of parallel strands of the wound coil (15), K D is the additional loss factor of the wound coil (15), A is the maximum allowable overheat parameter of the wound coil (15), B is the overheat parameter of the wound coil (15) at the start of the short circuit, where: In the above formula (8), θ k is the limit temperature of the wound coil (15), t 0 is the time elapsed after the start of the short circuit, θ N is the temperature of the wound coil (15) at the start of the short circuit, and lg is the logarithm symbol; During design, when the time t for the short-circuit current steady value calculated according to the above formula (6) to pass through the winding is greater than the required value, it is determined that the design scheme meets the thermal stability requirement.

10. A design method of the adjustable reactor for switch short-circuit test according to claim 1, characterized in that: including determining the dynamic stability calculation method under short-circuit current: Assume that the maximum short-circuit current that the coil assembly can withstand is I y , and its calculation is as follows: In the above formula (9), α is the shape coefficient of the wound coil (15), h is the calculated height of the wound coil (15), m is the number of parallel strands of the wound coil (15), and F ng is the allowable force per turn of the wound coil (15) per unit length, and its calculation is as follows: In the above formula (10), q is the cross-sectional area of the metal plate forming the wound coil (15), σ is the allowable stress of the wire turn, E is the elastic modulus of the metal plate, l is the length of the outer layer wire turn of the wound coil (15) between the two coil layer positioning blocks (14), and its calculation is as follows: In the above formula (11), D 2 is the diameter of the outer turns of the wound coil (15), l 1 is the width of the coil interlayer positioning block (14), and n is the number of coil interlayer positioning blocks (14); During design, when the short-circuit current calculated according to the above formula (9) is greater than the required short-circuit current peak value, it is determined that the design scheme meets the dynamic stability requirement.

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