CN112345967A - Transformer iron core ground fault diagnosis simulation method and device based on equivalent method - Google Patents
Transformer iron core ground fault diagnosis simulation method and device based on equivalent method Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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- G—PHYSICS
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/10—Numerical modelling
Abstract
A transformer iron core ground fault diagnosis simulation method and device based on an equivalence method. Establishing a transformer three-dimensional finite element model based on an equivalence method idea in ANSYS software, simulating a transformer core ground fault, and performing three-dimensional research and analysis on the iron core, the high-low voltage side winding and the coil simulating the conduction fault of the transformer to be simulated by using a three-dimensional anisotropic conductivity formula and a three-dimensional anisotropic conductivity formula. Different fault types are set on the iron core of the simulation device, and the relation between the fault current and the fault position is detected and obtained. And equivalently replacing a complex grounding condition by using a short-circuit coil to diagnose the fault. The upper end of a transformer iron core of the device is provided with an upper iron yoke surface, a high-low voltage simulation winding is arranged in a transformer box body, and a fault short circuit wire is arranged in the high-low voltage simulation winding. And the fault short-circuit lead is in short-circuit contact with the short-circuit grounding points of the left iron yoke surface and the upper iron yoke surface respectively to form a fault loop simulating the transformer. The method is simple, rapid, convenient and accurate in troubleshooting and solving of the power transformer faults.
Description
Technical Field
The invention belongs to the technical field of power equipment fault diagnosis, and relates to a transformer iron core ground fault diagnosis simulation method and device based on an equivalence method.
Background
When the transformer iron core has a multipoint earth fault, a fault loop is formed between the iron core and the ground, and fault current is generated. The fault current can cause additional loss in the iron core, and the fault current causes the local high temperature of the iron core, and then leads to the decomposition of transformer oil, and insulating properties descends, and then blows the grounding piece, causes the suspension potential, even burns out the iron core.
The traditional methods for detecting whether the transformer core is grounded at multiple points generally comprise three methods, namely a method for measuring the insulation resistance of the core, an electrical method for measuring the current of the core during operation and a gas chromatography method for detecting the characteristics of the transformer insulation oil. However, these methods can only roughly diagnose whether the multi-point ground fault exists, and the judgment of the fault position usually needs to be manually checked one by one, which is time-consuming and labor-consuming. Therefore, the method is particularly important for detecting the current rule of the grounding fault of the transformer iron core and carrying out fault position analysis research. The accurate and effective fault position prediction can timely prevent and control the occurrence of multipoint ground faults, improve the running reliability of the transformer, prolong the overhaul period and prolong the service life of the transformer, and compared with the traditional means, the method has the advantages of no substitution and extremely wide application prospect.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a transformer core ground fault diagnosis simulation method and device based on an equivalence method, and solves the problems of difficult fault classification and fault position judgment and difficult troubleshooting processing when a transformer core is grounded at multiple points.
The purpose of the invention is achieved by the following steps: and creating a simulation model capable of simulating the grounding of the transformer core, wherein the simulation model is based on the idea of an equivalence method. Establishing a three-dimensional finite element model of the transformer in finite element analysis software ANSYS, and performing three-dimensional research and analysis on an iron core, a high-low voltage side winding and a coil for simulating a conduction fault of the transformer to be simulated on the simulation model by using a three-dimensional anisotropic conductivity formula and a three-dimensional anisotropic permeability formula; setting different fault types on the simulation model iron core, and detecting and acquiring the relation between the fault current and the fault position; and equivalently replacing a complex grounding condition by using a short-circuit coil to obtain an iron core multipoint grounding fault model of the transformer, and performing fault diagnosis.
The method comprises the following specific steps:
step 1): the actual iron core lamination is equivalent to a uniform and continuous real iron core, and an equivalent conductivity formula and an equivalent permeability formula of the homogeneous iron core are provided according to an equivalent method theory;
wherein F is the iron core stacking coefficient, sigma is the electrical conductivity of the silicon steel sheet body, d is the thickness of the single silicon steel sheet, and a is the single sheetWidth of silicon steel sheet; mu is the bulk permeability of the silicon steel sheetfx、μfy、μfzMagnetic permeability mu in x, y and z directions of silicon steel sheet body0The vacuum magnetic permeability of the silicon steel sheet is obtained;
step 2): setting various parameters of the transformer in an ANSYS Maxwell transient field, and establishing a basic model of the transformer;
step 3): setting a fault area in an ANSYS Maxwell 3D current field, and equivalently replacing a complex grounding condition with a short circuit coil to obtain a transformer iron core multipoint grounding fault model;
step 4): and simulating two points at different positions on the iron core into a group of ground by using the established transformer multipoint ground model, classifying the transformer multipoint ground fault into two types, acquiring the current calculation value after each group of simulation, recording the current calculation values into a book, and performing comparative analysis.
In step 2), setting parameters including the material type, the conductivity and the magnetic permeability of an iron core, the connection group of high and low voltage side windings and the voltage grade in an ANSYS Maxwell transient field in ANSYS software; and establishing a transformer basic model to perform 3D finite element modeling in x, y and z directions for a high-low voltage side winding of a transformer iron core and a coil for simulating conduction faults.
In the step 3), a three-phase double-winding core type EI-type transformer is used as a simulation object, a medium-low frequency model is used, medium-low frequency voltage is input, and the two-point grounding condition of the equivalent complexity of the short circuit of the conducting wire on the iron yoke of the transformer is utilized.
In step 4), the calculation of the fault current after the iron core is grounded comprises the following steps: the magnitude of the magnetic flux contained by the circuit; and the alternating current resistance is arranged between the two grounding points of the iron core under the input frequency.
In the step 4), the multipoint ground faults of the transformer are classified into two types, one type is a left iron yoke of the exposed surface of the iron core when the position rule of the multipoint ground faults of the exposed surface of the silicon steel sheet is discussed; one is that when the position rule of multipoint earth fault in the thickness direction of silicon steel sheet is discussed, the transformer is facing to the upper surface of iron core, namely the thickness direction of silicon steel sheet.
And 3D finite element modeling is carried out by using ANSYS software, the model of the adopted transformer is S10-6300/35, the model of the silicon steel sheet is Z11, and the transformer is subjected to fault position change and fault loop current is collected in an ANSYS Maxwell transient field.
The device for the transformer iron core multipoint ground fault diagnosis simulation method based on the equivalence method comprises a transformer box body and a transformer iron core. An upper iron yoke surface is arranged at the upper end of a transformer iron core of the device, a high-low voltage simulation winding is arranged in a transformer box body, and the high-low voltage simulation winding comprises laminated silicon steel sheets with an E-shaped structure, an iron core grounding bar and a fault short circuit lead; the core ground bar is in short circuit contact with the transformer core.
The fault short-circuit lead is respectively connected with the short-circuit grounding point m of the left iron yoke surface of the transformer iron core at the grounding point1～m6Short-circuit contact, short-circuit grounding point n to upper yoke face1～n6Short-circuit contacts; and the short circuit grounding point of the upper iron yoke surface, the iron core grounding bar and the fault short circuit lead form a fault loop.
The short circuit grounding point of the left iron yoke surface of the transformer iron core forms a fault loop with the iron core grounding bar and the fault short circuit lead.
The upper end and the lower end of the device are respectively fixed by an upper clamping piece and a lower clamping piece, the transformer box is reinforced by a penetrating screw rod, the left clamping piece, the right clamping piece and the binding band are combined and fastened by an insulating bolt, and the potential difference of parts in a strong electric field is discharged from an iron core grounding bar on a silicon steel sheet.
The transformer iron core ground fault diagnosis device adopts different transformer iron core components, and when the ground fault position of the exposed surface of the silicon steel sheet is diagnosed, a fault loop formed by a left side iron yoke short circuit grounding point of the exposed surface of the iron core, an iron core grounding bar and a fault short circuit wire is used; when the grounding fault position in the thickness direction of the silicon steel sheet is diagnosed, a fault loop formed by the upper iron yoke surface short circuit grounding point, the iron core grounding bar and the fault short circuit conducting wire is used.
And different short circuit grounding points of the left iron yoke are respectively and short-circuited with the fault short circuit lead to form a silicon steel sheet exposed surface ground fault current data set.
And different short circuit grounding points of the upper iron yoke surface are respectively in short circuit with the fault short circuit lead to form a fault short circuit upper iron yoke surface fault current data set.
A three-phase double-winding core type EI-type transformer is adopted as a simulation object; a medium-low frequency model is adopted, medium-low frequency current and voltage are input, and the model number of the silicon steel sheet is Z11.
The model of the adopted three-phase double-winding core EI-type transformer is S10-6300/35.
The invention has the positive effects that:
(1) the method is based on the idea of an equivalent method, so that huge calculation cost caused by direct fine subdivision of the iron core silicon steel sheet by a finite element is avoided.
(2) The invention utilizes the established three-dimensional finite element model to carry out simulation, thereby not only avoiding the destructiveness and the operation difficulty of the simulation of the solid transformer test in engineering, but also having strong simulation timeliness and good effect because the simulation can acquire a large amount of data for rapid analysis.
(3) According to the method, the fault position rule analysis is carried out through the obtained model fault current, the positioning is accurate, the working efficiency is improved for maintainers, the working life of the transformer is prolonged, and therefore effective guarantee is further provided for equipment safety.
Drawings
Fig. 1 is an overall schematic diagram of a transformer core ground fault simulation apparatus of the present invention.
Fig. 2 is a schematic diagram of the mechanical structure of the core ground fault of the present invention.
Fig. 3 is a schematic diagram of the yoke surfaces and different ground fault locations on the transformer of the present invention.
In the figure, 1 upper yoke surface, 2 high-low voltage winding, 3 penetrating screw rods, 4 upper and lower clamping pieces, 5 iron cores, 6 iron core grounding bars, 7 fault short circuit wires, 31 left and right clamping pieces, 32 insulating bolts, 41 binding bands, 42 insulating paper boards, 51 laminated silicon steel sheets, n1～n6Different short circuit contact points on the upper yoke surface, m 1-m6Different shorting contacts on the left yoke face, where x, y, z represent three dimensional directions on the left yoke face of the transformer core.
Detailed Description
The equivalent method of the invention is to use a three-dimensional anisotropic conductivity formula and a magnetic conductivity formula to make the actual discontinuous uneven iron core equivalent to a homogeneous iron core. In order to reduce the finite element calculation cost, the three-dimensional anisotropy is considered, the iron core laminations with the large number are equivalent to a uniform and continuous real iron core, a transformer multipoint grounding finite element calculation model is established, and the finite element calculation and the rule analysis are carried out on the multipoint grounding fault current of the test transformer under the three-dimensional current field. The equivalent conductivity provided by the invention is suitable for calculating the multipoint earth fault current of the laminated core, and for laminated core transformers of different models, different core structures and shapes only influence the parameter size without influencing the formula.
In order to effectively simulate the simulation and simultaneously consider the simplicity and controllability of the experiment, the finite element modeling is carried out by taking the transformers of models S10-6300/35 as simulation objects in the embodiment. The parameters of the transformer, including the shape, the size, the rated capacity and the like of the transformer, are obtained through the use specification and relevant data of the model transformer.
The iron core material adopted by the model is Z11 oriented electrical silicon steel sheet produced by Nippon Nissan iron company, and various parameters of the silicon steel sheet are shown in Table 1.
TABLE 1
| Parameter(s) | Numerical value |
| Thickness (d/mm) | 0.35 |
| Conductivity (sigma/S/m) | 2083333 |
| Relative magnetic permeability (mu)r) | 36500 |
| Coefficient of stacking | 0.96 |
| Density (kg/m)3) | 7650 |
Simulation environment of the embodiment: and (3) setting various parameters of the transformer in an ANSYS Maxwell transient field by using ANSYS software, and establishing a basic model of the transformer, wherein the parameters of the power transformer are shown in a table 2.
TABLE 2
| Parameter(s) | Numerical value |
| Rated capacity (KVA) | 6300 |
| Rated voltage/V of high and low voltage | 35000/10500 |
| Type of silicon steel sheet | Z11 |
| High and low voltage coil turns/turn | 550/286 |
A fault area is set in an ANSYS Maxwell 3D current field, and a short-circuit coil is used for equivalently replacing a complex grounding condition to obtain a three-dimensional multi-point grounding fault model of the transformer core in the x direction, the y direction and the z direction. A medium-low frequency model is adopted, medium-low frequency voltage is input, and the equivalent complex two-point grounding condition of the short circuit of a lead on a transformer yoke is utilized.
The calculation of the fault current after the iron core is grounded needs to determine 1): the magnitude of the magnetic flux contained by the circuit; 2) and the alternating current resistance is arranged between the two grounding points of the iron core under the input frequency. The three-dimensional finite element method can accurately calculate the two parameters. The two-point grounding of the iron core is equivalent to two-point short circuit in nature, and the simulation model utilizes the equivalent two-point grounding of the short circuit lead on the iron yoke of the transformer. In order to be able to directly obtain the fault current value, the wire loop is set as a single-turn coil, and the corresponding coil is set as a short circuit at the coil setting interface. Thus, the current value in the coil, that is, the multipoint earth fault current value can be directly acquired in the subsequent processing.
And simulating two-point grounding groups at different positions of the iron core on the established transformer multipoint grounding model, wherein the specific positions are shown as grounding points in fig. 3. The grounding points shown in fig. 3 are divided into two groups, the first group being the short-circuit grounding point m of the left return yoke1～m6And acquiring fault current according to the movement of the arrow direction. The second group being short-circuit earthing points n of the upper yoke1～n6The fault current is obtained by moving according to the arrow direction. When the position rule of the multipoint ground fault on the exposed surface of the silicon steel sheet is discussed, a two-point ground fault simulation experiment is carried out on the first group; and when the position rule of the multipoint grounding fault in the thickness direction of the silicon steel sheet is discussed, the grounding points in the second group are connected pairwise respectively to carry out simulation experiments.
Three-dimensional anisotropic equivalent conductivity:
equivalent permeability of the homogeneous model:
wherein F is the iron core stacking coefficient, sigma is the electrical conductivity of the silicon steel sheet body, d is the thickness of the single silicon steel sheet, a is the width of the single silicon steel sheet, mu is the magnetic conductivity of the silicon steel sheet body, and mufx、μfy、μfzAre respectively provided withIs the magnetic permeability mu of the silicon steel sheet body in the x, y and z directions0Is the vacuum magnetic permeability of the silicon steel sheet.
The transformer core multipoint ground fault diagnosis simulation based on the equivalence method of the embodiment is carried out in a simulation device.
Performing three-dimensional research and analysis on an iron core, a high-low voltage side winding and a coil simulating conduction fault of a simulation object transformer on a simulation device; setting different fault types on the simulation model iron core, and detecting and acquiring the relation between the fault current and the fault position; and (3) equivalently replacing a complex grounding condition by using a short-circuit coil to obtain a simulation object transformer iron core multipoint grounding fault model, and performing fault diagnosis.
An upper yoke surface 1 is arranged at the upper end of the transformer, a high-low voltage simulation winding 2 is arranged in a transformer box body, and the high-low voltage simulation winding 2 comprises laminated silicon steel sheets 51 with an E-shaped structure, an iron core grounding bar 6 and a fault short circuit lead 7; the core ground bar 6 is in short-circuit contact with the core 5.
The upper end and the lower end of the device are respectively fixed by an upper clamping piece 4 and a lower clamping piece 4, the transformer box is reinforced by a penetrating screw rod 3, and the left clamping piece 31, the right clamping piece 31 and the binding band 41 are combined and fastened by an insulating bolt 32.
The gap between the iron core 5 and the binding band 41 is filled with an insulating paper sheet 42.
And the iron core grounding bar 6 on the silicon steel sheet discharges the potential difference of the parts in a strong electric field.
Short-circuit grounding point m of fault short-circuit lead 7 and left iron yoke surface of transformer iron core 5 respectively1～m6Short-circuit contact, short-circuit grounding point n with upper yoke face 11～n6Shorting the contacts.
Short-circuit grounding point n of upper yoke surface 11～n6And the fault circuit is respectively formed with the iron core grounding bar 6 and the fault short-circuit lead 7, and the complex condition of the iron yoke surface grounding fault on the simulation object is equivalent.
Short-circuit grounding point m of left iron yoke surface of transformer iron core 51～m6A fault loop is formed respectively with the iron core grounding bar 6 and the fault short-circuit lead 7, and the short-circuit grounding point m of the left iron yoke surface of the transformer iron core 51～m6And the fault circuit, the iron core grounding bar 6 and the fault short-circuit lead 7 form a fault loop, and the complex condition of the grounding fault of the exposed surface of the silicon steel sheet of the simulation object is equivalent.
The simulation of the ground fault diagnosis of the transformer core adopts different transformer core components, and when the ground fault position of the exposed surface of the silicon steel sheet is diagnosed, the short-circuit grounding point m of the left iron yoke of the exposed surface of the iron core is used1～m6A fault loop is formed by the core grounding bar 6 and the fault short-circuit lead 7; when diagnosing the position of a ground fault in the thickness direction of a silicon steel sheet, a short-circuit grounding point n of an upper yoke surface 1 is used1～n6A fault loop is formed by the core grounding bar 6 and the fault short-circuit lead 7; the fault current at different positions is obtained by continuously changing the position of the short-circuit fault conductor 7.
Short-circuit earthing point m on left yoke1～m6And respectively form a silicon steel sheet exposed surface earth fault current data set after short circuit contact with the fault short circuit lead 7.
Short-circuit grounding point n of upper yoke surface 11～n6And the short circuit of the upper iron yoke surface and the short circuit of the fault short circuit lead 7 are respectively formed into an upper iron yoke surface grounding fault current data group.
In the embodiment, a three-phase double-winding core type EI-type transformer is adopted as a simulation object; the transformer model is S10-6300/35. A medium-low frequency model is adopted, medium-low frequency current and voltage are input, and the model of the silicon steel sheet is Z11.
The embodiment is verified by building a model in simulation software ANSYS Electronics.
The simulation result proves that the simulation diagnosis method achieves better fault diagnosis performance than the traditional method for monitoring the earth fault. The method and the device can accurately and reliably provide good reference application value for intelligent power station service management.
Claims (10)
1. A transformer iron core multipoint ground fault diagnosis simulation method based on an equivalence method is characterized by comprising the following steps: establishing a simulation model capable of simulating the grounding of the transformer core, establishing a three-dimensional finite element model of the transformer in finite element analysis software ANSYS based on the idea of an equivalent method, and performing three-dimensional research and analysis on the iron core, the high-low voltage side winding and the coil for simulating the conduction fault of the transformer to be simulated on a simulation device by using a three-dimensional anisotropic conductivity formula and a three-dimensional anisotropic magnetic conductivity formula; setting different fault types on the simulation model iron core, and detecting and acquiring the relation between the fault current and the fault position; a short-circuit coil is used for equivalently replacing a complex grounding condition to obtain a transformer iron core multipoint grounding fault model for fault diagnosis;
the method comprises the following specific steps:
step 1): the actual iron core lamination is equivalent to a uniform and continuous real iron core, and an equivalent conductivity formula and an equivalent permeability formula of the homogeneous iron core are provided according to an equivalent method theory;
f is an iron core stacking coefficient, sigma is the conductivity of the silicon steel sheet body, d is the thickness of a single silicon steel sheet, and a is the width of the single silicon steel sheet; mu is the bulk permeability of the silicon steel sheetfx、μfy、μfzMagnetic permeability mu in x, y and z directions of silicon steel sheet body0The vacuum magnetic permeability of the silicon steel sheet is obtained;
step 2): setting various parameters of the transformer in an ANSYS Maxwell transient field, and establishing a basic model of the transformer;
step 3): setting a fault area in an ANSYS Maxwell 3D current field, and equivalently replacing a complex grounding condition with a short circuit coil to obtain a transformer iron core multipoint grounding fault model;
step 4): and simulating two points at different positions on the iron core into a group of ground by using the established transformer multipoint ground model, classifying the transformer multipoint ground fault into two types, acquiring the current calculation value after each group of simulation, recording the current calculation values into a book, and performing comparative analysis.
2. The equivalent method-based transformer core multipoint ground fault diagnosis simulation method of claim 1, characterized in that: in step 2), setting parameters including the material type, the conductivity and the magnetic permeability of an iron core, the connection group of high and low voltage side windings and the voltage grade in an ANSYS Maxwell transient field in ANSYS software; and establishing a transformer basic model to perform 3D finite element modeling in x, y and z directions for a high-low voltage side winding of a transformer iron core and a coil for simulating conduction faults.
3. The equivalent method-based transformer core multipoint ground fault diagnosis simulation method of claim 1, characterized in that: in the step 3), a three-phase double-winding core type EI-type transformer is used as a simulation object, a medium-low frequency model is used, medium-low frequency voltage is input, and the two-point grounding condition of the equivalent complexity of the short circuit of the conducting wire on the iron yoke of the transformer is utilized.
4. The equivalent method-based transformer core multipoint ground fault diagnosis simulation method of claim 1, characterized in that: in step 4), the calculation of the fault current after the iron core is grounded comprises the following steps: the magnitude of the magnetic flux contained by the circuit; and the alternating current resistance is arranged between the two grounding points of the iron core under the input frequency.
5. The equivalent method-based transformer core multipoint ground fault diagnosis simulation method of claim 1, characterized in that: in the step 4), the multipoint ground faults of the transformer are classified into two types, one type is a left iron yoke of the exposed surface of the iron core when the position rule of the multipoint ground faults of the exposed surface of the silicon steel sheet is discussed; one is that when the position rule of multipoint earth fault in the thickness direction of silicon steel sheet is discussed, the transformer is facing to the upper surface of iron core, namely the thickness direction of silicon steel sheet.
6. The equivalent method-based transformer core multipoint ground fault diagnosis simulation method of claim 3, characterized in that: and 3D finite element modeling is carried out by using ANSYS software, the model of the adopted transformer is D10-6300/35, the model of the silicon steel sheet is Z11, and the transformer is subjected to fault position change and fault loop current is collected in an ANSYS Maxwell transient field.
7. The device for the multipoint earth fault diagnosis simulation method of the transformer core based on the equivalence method according to claim 1, is characterized in that: the transformer comprises a transformer box body and a transformer core (5), wherein an iron yoke surface (1) is arranged at the upper end of the transformer core (5), a high-low voltage simulation winding (2) is arranged in the transformer box body, and the high-low voltage simulation winding (2) comprises laminated silicon steel sheets (51) with an E-shaped structure, an iron core grounding bar (6) and a fault short circuit lead (7); the iron core grounding bar (6) is in short-circuit contact with the transformer iron core (5);
the fault short-circuit lead (7) is respectively connected with a short-circuit grounding point (m) of the left iron yoke surface of the transformer iron core (5)1～m6) Short-circuit contact, short-circuit grounding point (n) with upper yoke surface (1)1～n6) Short-circuit contacts;
short-circuit grounding point (n) of upper yoke surface (1)1～n6) A fault loop is formed by the iron core grounding bar (6) and the fault short-circuit lead (7);
short-circuit grounding point (m) of left yoke surface of transformer core (5)1～m6) A fault loop is formed by the iron core grounding bar (6) and the fault short-circuit lead (7);
the upper end and the lower end of the device are respectively fixed by an upper clamping piece and a lower clamping piece (4), a feed-through screw rod (3) is used for reinforcing a transformer box, a left clamping piece, a right clamping piece (31) and a binding band (41) are combined and fastened by an insulating bolt (32), and a gap between an iron core (5) and the binding band (41) is filled by an insulating paper board (42); and an iron core grounding bar (6) on the silicon steel sheet is in the discharge of potential difference of parts in a strong electric field.
8. The transformer core ground fault simulation device based on the equivalence method according to claim 1, wherein: the transformer core ground fault diagnosis device adopts different transformer core components, and when the ground fault position of the exposed surface of the silicon steel sheet is diagnosed, the left side yoke short circuit grounding point (m) of the exposed surface of the iron core is used1～m6) A fault loop formed by the iron core grounding bar (6) and the fault short-circuit lead (7); when diagnosing the position of a ground fault in the thickness direction of a silicon steel sheet, an upper yoke surface (1) is used to short-circuit a ground point (n)1～n6) A fault loop formed by the iron core grounding bar (6) and the fault short-circuit lead (7);
different short circuit grounding points (n) of the upper yoke surface (1)1～n6) The short circuit of the short circuit wire and the fault short circuit wire (7) respectively forms a silicon steel sheet exposed surface earth fault current data set;
different short circuit grounding points (m) on left side yoke surface1～m6) And the fault short-circuit wires (7) are respectively short-circuited to form a fault short-circuit upper yoke surface fault current data group.
9. The transformer core ground fault simulation device based on the equivalent method as claimed in claim 7, wherein: a three-phase double-winding core type EI-type transformer is adopted as a simulation object; a medium-low frequency model is adopted, medium-low frequency current and voltage are input, and the model number of the silicon steel sheet is Z11.
10. The transformer core ground fault simulation device based on the equivalent method as claimed in claim 9, wherein: the adopted three-phase double-winding core EI-type transformer has the model number of S10-6300/35.
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| CN115825809A (en) * | 2023-02-17 | 2023-03-21 | 国网山西省电力公司电力科学研究院 | Transformer core multipoint ground fault simulation device and evaluation method |
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| CN115825809A (en) * | 2023-02-17 | 2023-03-21 | 国网山西省电力公司电力科学研究院 | Transformer core multipoint ground fault simulation device and evaluation method |
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