A combined transformer device with high-frequency suppression function for GIS and GIS unit

Abstract

The application provides a combined mutual inductor device with high-frequency suppression function for GIS and a GIS unit. The device comprises a center guide rod, a magnetic ring string, a shielding cover, a polar plate and a mutual inductor shell. The magnetic ring string and the shielding cover are sequentially sleeved outside the center guide rod, and the shielding cover is connected with the center guide rod. The magnetic ring string is provided with an inner insulation layer between the center guide rod and the shielding cover. The mutual inductor shell is sleeved outside the shielding cover, and the polar plate is sleeved between the shielding cover and the mutual inductor shell. The polar plate and the mutual inductor shell and the polar plate and the shielding cover are filled with insulation medium to form an outer insulation layer. When VFTO is generated, the conductor section where the magnetic ring string is located shows a large inductive reactance due to the high frequency of the traveling wave above MHz, the steepness of the traveling wave is reduced, the magnetic ring string generates eddy current loss at high frequency, the energy of the traveling wave is dissipated in the form of heat energy, and the amplitude is reduced.

Description

Technical Field

[0001] This invention relates to the field of intelligent substation technology, and more specifically, to a combined instrument transformer device and GIS unit for GIS with high-frequency suppression function. Background Technology

[0002] Gas-insulated substations (GIS) are widely used in power systems due to their compact structure, reliable operation, and low maintenance requirements. The opening and closing of disconnecting switches on unloaded short busbars can generate very fast transient overvoltages (VFTOs). These VFTOs are characterized by high amplitude, steep wavefront, high frequency, and multiple consecutive pulses, threatening the insulation of primary electrical equipment and causing electromagnetic interference to secondary equipment, thus affecting the normal operation of the system. Therefore, research on transient overvoltage suppression technologies, represented by VFTOs, is of great significance for improving the safety and reliability of power grid operation.

[0003] Currently, there are several ways to suppress VFTO high-frequency loss by adding GIS loops, mainly including:

[0004] (1) Adding damping resistors to the disconnecting switch. This method is the most effective, technically mature, and widely used in engineering among existing VFTO suppression methods. However, adding damping resistors will complicate the structure of the disconnecting switch, reduce the long-term reliability of the equipment, and significantly increase the cost, making it uneconomical. In addition, this method is not suitable for the renovation of GIS systems already in operation on site, so it is difficult to fully meet the engineering requirements for VFTO suppression.

[0005] (2) High-frequency magnetic ring device. The specific measure is to install a string of magnetic rings on the conductor rod of the GIS busbar. The high inductance of the magnetic rings at high frequencies reduces the steepness of the traveling wave, while the traveling wave energy is absorbed through losses such as eddy currents and hysteresis. The principle of this method is feasible, and some prototype development work has been carried out. However, there are no clear recommendations on how to select a suitable installation and modification location, magnetic ring type, and quantity in engineering.

[0006] (3) Novel VFTO suppression methods, mainly including bus resonant structures, damping busbars, coatings, etc., are still in the scientific research and exploration stage.

[0007] In summary, existing VFTO suppression methods have varying degrees of shortcomings in terms of economy, applicability, and reliability, making it difficult to adequately meet the actual needs of VFTO suppression in GIS substations. Therefore, there is an urgent need for a device that combines the characteristics of existing equipment (economical and without significant modifications to the original GIS) with VFTO suppression functionality, in order to conveniently meet the engineering requirements for VFTO suppression in GIS substations. Summary of the Invention

[0008] In view of this, the present invention proposes a combined instrument transformer device and GIS unit with high frequency suppression function for GIS, aiming to solve the problem that existing VFTO suppression methods are difficult to meet the actual needs of VFTO suppression in GIS substations.

[0009] On one hand, this invention proposes a combined current transformer device for GIS with high-frequency suppression function. The device includes: a central guide rod, a magnetic ring string, a shield, an electrode plate, and a current transformer housing. The magnetic ring string and the shield are sequentially fitted onto the outside of the central guide rod, and the shield is also connected to the central guide rod. An inner insulating layer is provided between the magnetic ring string and both the central guide rod and the shield for insulating and supporting the magnetic ring string. The current transformer housing is fitted onto the outside of the shield, and the electrode plate is fitted onto the shield. The space between the shield and the transformer housing, between the electrode plate and the transformer housing, and between the electrode plate and the shield are all filled with an insulating medium to form an outer insulating layer. The electrode plate and the shield form a high-voltage arm capacitor of the voltage sensor, and the electrode plate and the transformer housing form a low-voltage arm capacitor of the voltage sensor. A Rogowski coil structure is provided on the inner wall of the transformer housing as a current sensor. Both the electrode plate and the transformer housing are provided with wires for connecting the secondary measurement integrated low-voltage arm to form a low-voltage arm circuit to complete the measurement of voltage and current.

[0010] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the magnetic ring string includes: a plurality of magnetic rings; wherein each of the magnetic rings is arranged at intervals along the axial direction of the magnetic ring, and an insulating pad is provided between any two adjacent magnetic rings.

[0011] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the minimum value of the magnetic ring spacing between adjacent magnetic rings is determined based on the intersection of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve; wherein, the voltage stress amplitude curve under transient voltage is a straight line with the magnetic ring spacing between adjacent magnetic rings as the abscissa and the voltage stress amplitude under transient voltage of the insulating pad as the ordinate, and the critical breakdown voltage curve is a straight line with the magnetic ring spacing between adjacent magnetic rings as the abscissa and the critical breakdown voltage of the insulating pad as the ordinate.

[0012] Furthermore, in the aforementioned combined instrument transformer device for GIS with high-frequency suppression function, the voltage stress amplitude curve under transient voltage is determined using the following formula:

[0013]

[0014] Wherein, U is the voltage stress amplitude under transient voltage; B is the saturation magnetic induction intensity of the magnetic ring; R4 is the outer diameter of the magnetic ring; R3 is the inner diameter of the magnetic ring; d1 is the thickness of the magnetic ring; d2 is the magnetic ring spacing between adjacent magnetic rings; and t is the rise time of SF6 breakdown between contacts in the GIS.

[0015] Furthermore, in the aforementioned combined instrument transformer device for GIS with high-frequency suppression function, the critical breakdown voltage curve is determined using the following formula:

[0016] U E =E×d2;

[0017] Among them, U E d1 is the critical breakdown voltage of the insulating pad between the magnetic rings; E is the dielectric strength of the insulating pad; d2 is the spacing between adjacent magnetic rings.

[0018] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the thickness d1 of the magnetic ring is calculated using the following formula:

[0019]

[0020] Where ρ is the resistivity of the magnetic ring; u r denoted as , where is the initial relative permeability of the magnetic ring.

[0021] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the inner diameter of the current transformer housing is determined based on the difference between the inner diameter of the GIS housing and the outer diameter of the central guide rod.

[0022] Furthermore, in the aforementioned combined instrument transformer device for GIS with high-frequency suppression function, the inner diameter R7 of the instrument transformer housing is calculated using the following formula:

[0023] R7 = R6 + R - R2;

[0024] Where R6 is the outer diameter of the shielding cover; R is the outer diameter of the GIS shell; and R2 is the outer diameter of the center guide rod.

[0025] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the high-voltage arm stray capacitance between the electrode plate and the shield constitutes the high-voltage arm capacitance of the voltage sensor. The high-voltage arm stray capacitance between the electrode plate and the shield is calculated using the following formula:

[0026]

[0027] Wherein, C1 is the stray capacitance of the high-voltage arm between the electrode and the shield; R6 is the outer diameter of the shield in meters; ε is the relative permittivity of the gas; ε0 is the permittivity in a vacuum; and L is the effective length of the electrode in meters.

[0028] Furthermore, in the aforementioned combined current transformer device for GIS with high-frequency suppression function, the low-voltage arm stray capacitance between the electrode plate and the housing constitutes the low-voltage arm capacitance of the voltage sensor. The low-voltage arm stray capacitance between the electrode plate and the housing is calculated using the following formula:

[0029]

[0030] Wherein, C2 is the low-voltage arm stray capacitance between the electrode and the outer casing; R7 is the inner diameter of the transformer casing, in meters; r2 is the outer diameter of the electrode, in meters; ε r ε0 is the relative permittivity of the insulating material; ε0 is the permittivity in vacuum; L is the effective length of the plate, in meters.

[0031] The present invention provides a combined instrument transformer device for GIS with high-frequency suppression function. Through a magnetic ring string set on the central guide rod, when VFTO occurs, due to the high frequency of the traveling wave (above MHz), the conductor section containing the magnetic ring string exhibits a large inductive reactance. The entire line is equivalent to having a nonlinear inductor connected in series, reducing the steepness of the traveling wave. Simultaneously, at high frequencies, the magnetic ring string generates eddy current losses, dissipating the energy of the traveling wave as heat, thus reducing its amplitude and effectively ensuring the safety of the electronic instrument transformer. The shielding cover outside the magnetic ring string ensures a uniform distribution of the internal field strength, guaranteeing measurement accuracy and meeting the actual requirements of VFTO suppression in GIS substations. This solves the problem that existing VFTO suppression methods are insufficient to meet the actual needs of VFTO suppression in GIS substations.

[0032] On the other hand, the present invention also proposes a GIS unit having the above-mentioned combined current transformer device for GIS with high frequency suppression function.

[0033] Furthermore, the aforementioned GIS unit further includes: two GIS segments, which are respectively disposed on both sides of the GIS combined instrument transformer device, and the two GIS segments are respectively connected to both ends of the GIS combined instrument transformer device through transition sections.

[0034] Since the combined instrument transformer device for GIS with high frequency suppression function has the above-mentioned effects, the GIS unit with the combined instrument transformer device for GIS with high frequency suppression function also has the corresponding technical effects. Attached Figure Description

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of a combined instrument transformer device for GIS with high-frequency suppression function provided in an embodiment of the present invention;

[0037] Figure 2 A cross-sectional view of a combined instrument transformer device for GIS with high-frequency suppression function provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of the magnetic ring string provided in an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the voltage stress amplitude curve and critical breakdown voltage curve of the magnetic ring under transient voltage provided in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the structure of the annular closed plate provided in an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the winding structure of the Rogowski coil provided in an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the structure of a GIS unit provided in an embodiment of the present invention. Detailed Implementation

[0043] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] Device Example:

[0045] See Figures 1 to 3 This figure illustrates a preferred structure of a combined instrument transformer device for GIS with high-frequency suppression function provided by an embodiment of the present invention. As shown, the device 100 includes: a central guide rod 1, a magnetic ring string 2, a shielding cover 3, an electrode plate 4, and an instrument transformer housing 5; wherein,

[0046] A magnetic ring string 2 and a shield 3 are sequentially fitted onto the outside of the central guide rod 1, and the shield 3 is also connected to the central guide rod 1. An inner insulating layer 6 is provided between the magnetic ring string 2 and both the central guide rod 1 and the shield 3 to provide insulation and support for the magnetic ring string 2. The transformer housing 5 is fitted onto the outside of the shield 3, and a pole plate 4 is fitted between the shield 3 and the transformer housing 5. Insulating media are filled between the pole plate 4 and the transformer housing 5, and between the pole plate 4 and the shield 3, forming an outer insulating layer 7. The pole plate 4 and the shield 3 together form the high-voltage arm capacitor of the voltage sensor, and the pole plate 4 and the transformer housing 5 together form the low-voltage arm capacitor of the voltage sensor. A Rogowski coil structure 8 is provided on the inner wall of the transformer housing 5 as a current sensor. Both the pole plate 4 and the transformer housing 5 are provided with wires for connecting to the secondary measurement integrated low-voltage arm 9 to form a low-voltage arm circuit to complete the measurement of voltage and current.

[0047] In specific implementation, the magnetic ring string 2 is fitted onto the central guide rod 1, and the magnetic ring string 2 is insulated from the central guide rod 1. This insulation can be achieved by filling with an insulating medium, such as polytetrafluoroethylene (PTFE), to form an inner insulating layer 6. A shielding cover 3 is fitted over the magnetic ring string 2 and is connected to the central guide rod 1, forming a reliable integral structure. The shielding cover 3 is also insulated from the magnetic ring string 2, and this insulation can be achieved by filling with an insulating medium, such as PTFE, to form an inner insulating layer 6. A transformer housing 5 is fitted over the shielding cover 3, and a plate 4 is provided between them as an induction electrode. The shielding cover 3 and the plate 4, i.e., the induction electrode, constitute the high-voltage arm capacitor of the voltage sensor. A Rogowski coil structure 8 is provided on the inner wall of the transformer housing 5, and the inner surface of the transformer housing 5 is integrated with the skeleton of the Rogowski coil structure 8, which can be used in conjunction with the secondary measurement integrated low-voltage arm 9 to complete voltage and current measurement functions. In this embodiment, an insulating medium, such as SF6, can be filled between the transformer housing 5 and the shield 3 to form an outer insulating layer 7. The secondary measurement integrated low-voltage arm 9 can be connected to the electrode plate 4 and the wires extending from the transformer housing 5 via measurement leads to achieve voltage and current measurement functions.

[0048] In this embodiment, as Figure 2 and Figure 3 As shown, the central guide rod 1 can be a hollow rod structure. Of course, in other embodiments, it can also be a solid rod structure. The hollow rod structure can reduce costs.

[0049] See also Figure 2 The magnetic ring string 2 includes: a plurality of magnetic rings 21; wherein, each magnetic ring 21 is arranged along the axial direction of the magnetic ring 21 (e.g., Figure 2The magnetic rings 21 are arranged at intervals in the horizontal direction shown, and an insulating pad 22 is provided between any two adjacent magnetic rings 21 to achieve insulation between the magnetic rings 21. Specifically, the insulating pad 22, the inner insulating layer 6 between the magnetic ring string 2 and the central guide rod 1, and the magnetic ring string 2 and the shield 3 can all be integrally formed by filling with an insulating medium such as polytetrafluoroethylene insulating medium.

[0050] In this embodiment, the selection of the magnetic ring 21 can be determined based on the GIS voltage level and the inner and outer diameters of the central guide rod 1. The magnetic ring 21 can be made of R2KB type ferrite, its saturation magnetic induction intensity B can be 0.5T, and its initial relative permeability U... r The resistivity ρ of the magnetic ring 21 can be 10³ to 10⁸ Ω·cm, which can be 2500. Figure 2 As shown, the magnetic ring 21 is fitted onto the central guide rod 1. The magnetic ring 21 includes the following dimensional parameters: the inner diameter R3, the outer diameter R4, the thickness d1 (axial width), and the spacing d2 (axial distance) between adjacent magnetic rings. In this embodiment, the magnetic ring 21 has a sheet-like structure. To maintain insulation between the magnetic ring sheets, an insulating pad 22 made of polytetrafluoroethylene (PTFE, with a dielectric constant of approximately 2.5) is placed between adjacent magnetic rings 21. Simultaneously, the space between the inner surface of the magnetic ring 21 and the outer surface of the central guide rod 1 is filled with PTFE insulating medium to form an inner insulating layer 6, which serves as both a fixation and insulation layer. The thickness of the inner insulating layer between the inner surface of the magnetic ring 21 and the outer surface of the central guide rod 1 is set as d3, in mm.

[0051] In this embodiment, the thickness d1 of the magnetic ring can be calculated using the following formula:

[0052]

[0053] Where ρ is the resistivity of the magnetic ring; u r denoted as , where is the initial relative permeability of the magnetic ring.

[0054] The thickness d1 of the magnetic ring 21 is selected according to the principle of optimal damping condition. The value of d1 should be as close as possible to the constraint calculation value. A value of 10mm is recommended for d1.

[0055] In this embodiment, the magnetic ring spacing d2 between adjacent magnetic rings and the thickness d3 of the inner insulation layer between the inner surface of magnetic ring 21 and the outer surface of the central guide rod 1 need to consider the voltage stress under transient voltage. The minimum value of the magnetic ring spacing d2 between adjacent magnetic rings is determined based on the intersection of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve. The voltage stress amplitude curve under transient voltage is a straight line with the magnetic ring spacing d2 between adjacent magnetic rings as the abscissa and the voltage stress amplitude U of the insulating pad under transient voltage as the ordinate. The critical breakdown voltage curve has the magnetic ring spacing d2 between adjacent magnetic rings as the abscissa and the critical breakdown voltage U of the insulating pad as the ordinate.E The vertical axis represents a straight line. Based on the horizontal axis of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve, the minimum value of the magnetic ring spacing d2 between adjacent magnetic rings is determined. That is, the horizontal axis of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve is used as the minimum value of the magnetic ring spacing d2 between adjacent magnetic rings. In other words, the magnetic ring spacing d2 between adjacent magnetic rings is greater than or equal to the horizontal axis of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve. Alternatively, all d2 values ​​to the right of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve meet the requirement.

[0056] In this embodiment, the voltage stress amplitude curve under transient voltage is determined using the following formula:

[0057]

[0058] Where U is the voltage stress amplitude under transient voltage; B is the saturation magnetic induction intensity of the magnetic ring, which can be 0.5T; R4 is the outer diameter of the magnetic ring; R3 is the inner diameter of the magnetic ring; d1 is the thickness of the magnetic ring; d2 is the magnetic ring spacing between adjacent magnetic rings; t is the rise time of SF6 breakdown between contacts in GIS, which is usually in the range of 5 to 20 ns, and is considered to be the most stringent 5 ns.

[0059] For all magnetic rings with different outer diameters R4 and inner diameters R3 that satisfy the requirement that the thickness d1 of the magnetic ring is 10 mm, the voltage stress amplitude U under transient voltage can be calculated according to the above calculation formula for different values ​​of d2, and the U-d2 curve, i.e. the voltage stress amplitude curve under transient voltage, can be plotted.

[0060] In this embodiment, the critical breakdown voltage U of the insulating pad between magnetic rings with different d2 values ​​can be calculated based on the dielectric strength E of the polyinsulating pad. E And draw U E The -d2 curve is the critical breakdown voltage curve; the critical breakdown voltage U of the insulating pad between the magnetic rings. E Determine using the following formula:

[0061] U E =E×d2;

[0062] Among them, U E d1 is the critical breakdown voltage of the insulating pad between the magnetic rings; E is the dielectric strength of the insulating pad; d2 is the spacing between adjacent magnetic rings.

[0063] Based on the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve, such as Figure 4As shown, the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve is determined. All d2 values ​​to the right of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve meet the requirements. In this embodiment, the abscissa of the intersection point of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve is 2mm, so d2≥2mm is sufficient to meet the requirements.

[0064] In this embodiment, from the perspective of voltage stress, the thickness d3 of the inner insulating layer between the inner surface of the magnetic ring 21 and the outer surface of the central guide rod 1 is required to be the same as d2. As shown in Figure 2, considering that d3 = R3 - R2, in order to control the overall structural dimensions as much as possible, the magnetic ring with the smallest R3 - R2 value is selected from the magnetic ring with a thickness d1 of 10 mm, and the value of R3 - R2 is greater than the U-d2 curve and U E The set of magnetic rings at the intersection of the -d2 curves.

[0065] In this embodiment, when determining the economical quantity of magnetic rings, i.e., the number of magnetic rings n, considers the saturation effect of the magnetic rings. The suppression effect varies under different traveling wave currents. When the current amplitude is low, a small number of magnetic rings can significantly reduce the steepness of the traveling wave; when the current amplitude is high, a larger number of magnetic rings are required. Considering the positive correlation between the transient current amplitude and the GIS voltage level, the number of magnetic rings 21 in the magnetic ring string 2 is determined based on the GIS voltage level. For example, the economical quantity of magnetic rings for a 1000kV GIS circuit is 50 pieces, and the recommended economical quantities n for 500kV, 330kV, 220kV, and 110kV GIS circuits are 25, 20, 10, and 5 pieces, respectively.

[0066] In this embodiment, the voltage stress U between the shielding cover 3 and the central guide rod 1 under transient conditions is... total The voltage stress of a single magnetic ring 21 can be approximately estimated using the product of the voltage stress amplitude U under the transient voltage of a single magnetic ring and the number of magnetic rings 21 inside the shield 3, i.e., calculated using the following formula:

[0067] U total =n×U;

[0068] And calculate the SF6 critical breakdown condition in GIS, satisfying U total The constraint distance is the constraint distance d that satisfies the voltage stress. 约 =U total ÷E, through the constraint distance d that satisfies the voltage stress 约 Comparisons with R3-R2 usually involve d 约 Since R3-R2 is less than 0, the design of the shielding cover should prioritize ease of installation. If d 约 If the value is greater than or less than R3-R2, then the magnetic ring 21 needs to be selected again.

[0069] In this embodiment, the shielding cover 3 can be a hollow cylindrical structure, and it can be a metal shielding cover, meaning the entire metal shielding cover is a hollow cylinder made of aluminum. The inner diameter R5 of the shielding cover 3 and the outer diameter R6 of the metal cover 3 can be determined according to actual conditions. For example, the inner diameter R5 of the metal cover 3 = R5 + d3 + 10mm, and the outer diameter R6 of the metal cover 3 = R5 + d3 + 11mm; of course, the inner and outer diameters of the metal cover 3 can also be calculated in other ways, which are not addressed in this embodiment. The shielding cover 3 is open at one end and closed at the other, meaning one end of the shielding cover 3 is open, and the other end can be provided with an annular closed plate 31 for connecting the central guide rod 1. A connecting plate can be provided on the outer wall of the central guide rod 1, for example, at approximately 9 / 10 of its length. The connecting plate has connecting holes, such as... Figure 5 As shown, the annular sealing plate 31 is provided with screw holes 311 corresponding to the connecting holes. Nuts can be used to fix the annular sealing plate 31 to the connecting plate, so as to ensure the reliable connection between the shielding cover 3 and the central guide rod 1 and to play a fixing role. In order to prevent corona generation, preferably, the corners of the shielding cover 3 are all rounded and smoothed. For example, the connection between the shielding cover 3 and the annular sealing plate 31 is provided with a rounded transition section 32 to prevent corona generation.

[0070] In this embodiment, to avoid altering the original insulation design and margin of the GIS, the inner diameter R7 of the transformer housing 5 is limited so that the distance between the inner surface of the transformer housing 5 and the outer surface of the shield 3 is equal to the difference between the original outer surface of the GIS, i.e., the distance between the outer surface of the GIS housing and the outer surface of the central guide rod 1. In other words, the inner diameter of the transformer housing is determined based on the difference between the outer diameter of the GIS housing and the outer diameter of the central guide rod. The inner diameter R7 of the transformer housing 5 is calculated using the following formula:

[0071] R7 = R6 + R - R2;

[0072] Wherein, R6 is the outer diameter of the shielding cover; R is the outer diameter of the GIS shell, i.e., the outer diameter of the GIS pipe 201 of GIS section 200; and R2 is the outer diameter of the central guide rod.

[0073] In this embodiment, as Figure 3As shown, plate 4 can be a cylindrical structure, such as a columnar stainless steel plate, which is fitted between the shielding cover 3 and the transformer housing 5 to form a coaxial structure of the GIS, thus forming a cylindrical capacitor. An insulating medium, such as SF6, needs to be filled between plate 4 and the transformer housing 5 to form an outer insulating layer 7. A wire is led out from both plate 4 and transformer housing 5 to connect to the secondary measurement low-voltage arm, forming a low-voltage arm circuit. The high-voltage arm stray capacitance C1 between the plate and the shielding cover, i.e., the high-voltage side stray capacitance between the columnar stainless steel plate and the metal shielding cover, constitutes the high-voltage arm capacitance of the capacitive voltage divider. Its size is related to the diameter of the transformer housing, conductor, and columnar stainless steel plate; that is, the high-voltage arm stray capacitance C1 between the plate and the shielding cover is determined based on the outer diameter of the shielding cover and the effective length of the plate. The high-voltage arm stray capacitance between the plate and the shielding cover is calculated using the following formula:

[0074]

[0075] Where C1 is the stray capacitance of the high-voltage arm between the electrode and the shield; R6 is the outer diameter of the shield in meters; ε is the relative permittivity of the gas; ε0 is the permittivity in a vacuum; and L is the effective length of the electrode in meters.

[0076] The low-voltage arm stray capacitance between the electrode and the housing constitutes the low-voltage arm capacitance of the voltage sensor. This low-voltage arm stray capacitance is calculated using the following formula:

[0077]

[0078] Where C2 is the low-voltage arm stray capacitance between the plate and the casing; R7 is the inner diameter of the transformer casing, in meters; r2 is the outer diameter of the plate, in meters; ε r ε0 is the relative permittivity of the insulating material; ε0 is the permittivity in vacuum; L is the effective length of the plate, in meters.

[0079] In this embodiment, the low-voltage arm is composed of stray capacitance between the columnar stainless steel plate (i.e., electrode plate 4) and the transformer housing 5, as well as an external integrated capacitor or resistor. The external integrated capacitor or resistor can be adjusted as needed to ensure that the high-voltage and low-voltage arms meet the voltage ratio requirements.

[0080] In this embodiment, for the current transformer, the primary circuit of the GIS electronic current transformer is the GIS center conductor, and the secondary circuit is an insulated wire wound around a ring-shaped magnetic core, commonly referred to as the CT winding. This CT winding is installed between the inner surface of the GIS housing and the metal shield, with the signal led out at the junction box on the GIS housing. One end of the metal shield is short-circuited to the GIS housing, and the other end is suspended, achieving effective shielding of the electric field but not the magnetic field, thus not affecting the measurement of the primary current. Typically, each GIS bay has multiple CT windings, installed between the GIS circuit breaker and the disconnecting switch. Regarding the Rogowski coil structure 8, since the transformer housing 5 is a cylindrical axisymmetric structure, the frame 81 of the Rogowski coil structure 8 is a ring structure, which can be a uniform cross-section non-magnetic material frame, and, as... Figure 6 As shown, a measuring wire 82 is wound around the outer edge of the frame 81. The measuring wire 82 is uniformly and tightly wound on a non-magnetic material frame with a uniform cross-section, forming a Rogowski coil structure 8. The frame 81 of the Rogowski coil structure 8 can be determined based on the inner diameter R7 of the transformer, that is, the outer radius of the frame is smaller than R7, and the inner diameter can be larger than the outer diameter of the electrode plate.

[0081] In summary, the combined instrument transformer device for GIS with high-frequency suppression function provided in this embodiment, through the magnetic ring string 2 set on the central guide rod 1, when VFTO occurs, due to the high frequency of the traveling wave (above MHz), the conductor section where the magnetic ring string 2 is located exhibits a large inductive reactance. The entire line is equivalent to a nonlinear inductor connected in series, and the steepness of the traveling wave will be reduced. At the same time, at high frequencies, the magnetic ring string will generate eddy current losses, and the energy of the traveling wave will be dissipated in the form of heat, thus reducing the amplitude and effectively ensuring the safety of the electronic instrument transformer. The shield 3 outside the magnetic ring string 2 ensures a uniform distribution of the internal field strength, ensuring the accuracy of the measurement and meeting the actual needs of GIS substations for VFTO suppression. This solves the problem that existing VFTO suppression methods cannot adequately meet the actual needs of GIS substations for VFTO suppression.

[0082] GIS Unit Example:

[0083] This embodiment also proposes a GIS unit, such as Figure 7 As shown, the GIS unit is equipped with the aforementioned combined instrument transformer device for GIS with high-frequency suppression function. The specific implementation process of the combined instrument transformer device for GIS with high-frequency suppression function can be found in the above description, and will not be repeated here.

[0084] The GIS unit also includes: GIS segment 200; wherein, there can be two GIS segments 200, respectively arranged on both sides of the GIS combined current transformer device 100 (e.g., Figure 6(as shown on the left and right sides), and the two GIS segments 200 are respectively connected to the two ends of the GIS combined current transformer device 100 via the transition section 300 (as shown on the left and right sides). Figure 6 The transition section 300 is connected to the GIS section 200 and the GIS combined instrument transformer device 100 in a detachable manner, forming an integral detachable structure for the GIS unit. To meet insulation performance requirements, the addition of a magnetic ring string 2 and a shield 3 to the central guide rod 1 in the GIS combined instrument transformer device 100 increases the overall space size. Therefore, the size of the instrument transformer housing 5 of the GIS combined instrument transformer device 100 needs to be designed according to the actual size of the added magnetic ring 21, and corresponding transition sections 300 are added at both ends so that the modified GIS combined instrument transformer device 100 can be connected to the GIS section 200.

[0085] Since the combined instrument transformer device for GIS with high frequency suppression function has the above-mentioned effects, the GIS unit with the combined instrument transformer device for GIS with high frequency suppression function also has the corresponding technical effects.

[0086] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0087] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0088] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A combined transformer device for GIS with a high frequency suppression function, characterized by, Includes: a central guide rod, a magnetic ring string, a shielding cover, pole plates, and the transformer housing; among which, The magnetic ring string and the shielding cover are sequentially fitted onto the outside of the central guide rod, and the shielding cover is also connected to the central guide rod; Each of the magnetic ring strings is provided with an inner insulating layer between itself and the central guide rod and the shielding cover, for insulating support of the magnetic ring strings; The transformer housing is fitted outside the shield, and the electrode plate is fitted between the shield and the transformer housing. The space between the electrode plate and the transformer housing, and between the electrode plate and the shield, is filled with an insulating medium to form an outer insulating layer. The electrode plate and the shield form a high-voltage arm capacitor of the voltage sensor, and the electrode plate and the transformer housing form a low-voltage arm capacitor of the voltage sensor. The inner wall of the transformer housing is provided with a Rogowski coil structure, which serves as a current sensor. Both the electrode plate and the transformer housing are provided with wires for connecting the secondary measurement integrated low-voltage arm to form a low-voltage arm circuit to complete the measurement of voltage and current. The magnetic ring string comprises: a plurality of magnetic rings; wherein... Each of the magnetic rings is arranged at intervals along the axial direction of the magnetic ring, and an insulating pad is provided between any two adjacent magnetic rings; The minimum spacing between adjacent magnetic rings is determined based on the intersection of the voltage stress amplitude curve under transient voltage and the critical breakdown voltage curve; wherein, the voltage stress amplitude curve under transient voltage is a straight line with the spacing between adjacent magnetic rings as the abscissa and the voltage stress amplitude of the insulating pad under transient voltage as the ordinate, and the critical breakdown voltage curve is a straight line with the spacing between adjacent magnetic rings as the abscissa and the critical breakdown voltage of the insulating pad as the ordinate; The voltage stress amplitude curve under transient voltage is determined using the following formula: ； in, This refers to the voltage stress amplitude under transient voltage. The saturation magnetic flux density of the magnetic ring; The outer diameter of the magnetic ring; This is the inner diameter of the magnetic ring; The thickness of the magnetic ring; The distance between adjacent magnetic rings; The rise time for SF6 breakdown between contacts in GIS; The critical breakdown voltage curve is determined using the following formula: ； wherein, is a critical breakdown voltage of the magnetic ring-to-ring insulation pad; is a dielectric strength of the insulation pad; is a magnetic ring-to-ring spacing between adjacent said magnetic rings; The thickness of the magnetic ring Calculate using the following formula: ； wherein the resistivity of the magnetic ring; the initial relative permeability of the magnetic ring.

2. The combined transformer device for GIS with high frequency suppression function according to claim 1, characterized in that, The inner diameter of the current transformer housing is determined based on the difference between the inner diameter of the GIS housing and the outer diameter of the central guide rod.

3. The combined transformer device for GIS with high frequency suppression function according to claim 2, characterized in that, The inner diameter of the transformer housing The calculation is made using the formula: ； in, The outer diameter of the shielding cover; The outer diameter of the GIS casing; The outer diameter of the central guide rod.

4. The combined instrument transformer device for GIS with high-frequency suppression function according to claim 1, characterized in that, The stray capacitance of the high-voltage arm between the electrode plate and the shield constitutes the high-voltage arm capacitance of the voltage sensor. The stray capacitance of the high-voltage arm between the electrode plate and the shield is calculated using the following formula: ； in, This refers to the high-voltage arm stray capacitance between the electrode plate and the shielding cover; The outer diameter of the shielding cover is in meters (m). The relative permittivity of the gas; The dielectric constant in a vacuum; This represents the effective length of the electrode, expressed in meters (m).

5. The combined instrument transformer device for GIS with high-frequency suppression function according to claim 1, characterized in that, The low-voltage arm stray capacitance between the electrode plate and the housing constitutes the low-voltage arm capacitance of the voltage sensor. The low-voltage arm stray capacitance between the electrode plate and the housing is calculated using the following formula: ； in, This refers to the low-voltage arm stray capacitance between the electrode plate and the outer casing; The inner diameter of the transformer housing is in meters (m). is the outer diameter of the electrode plate, in meters (m). The relative permittivity of the insulating material; The dielectric constant in a vacuum; This represents the effective length of the electrode, expressed in meters (m).

6. A GIS unit characterized in that, A combined current transformer device for GIS with high-frequency suppression function as described in any one of claims 1 to 5 is provided.

7. The GIS unit according to claim 6, characterized in that, Also includes: GIS segment; among which, The GIS segment consists of two sections, which are respectively located on both sides of the GIS combined instrument transformer device. Furthermore, the two GIS segments are respectively connected to both ends of the GIS combined instrument transformer device through transition sections.

Images