Dry-type reactor turn-to-turn short circuit fault positioning method based on magnetic field direction angle

Abstract

The invention discloses a dry type reactor turn-to-turn short circuit fault positioning method based on a magnetic field direction angle. Obtaining radial and axial magnetic field component data of an outer side designated area under different working conditions; dividing a measurement area according to a reactor structure and magnetic field distribution characteristics; screening optimal measurement areas under different working conditions based on the divided measurement areas and initial moment magnetic field components in the obtained radial and axial magnetic field component data; calculating a magnetic field direction angle of the optimal measurement area under different screened working conditions; making a sensor layout scheme according to the calculated magnetic field direction angles of the optimal measurement area under different working conditions and the change characteristics of the magnetic field direction angles of the measurement points under different working conditions, and determining each measurement point; fault positioning is realized by analyzing the magnetic field direction angle difference between the short-circuit working condition and the normal working condition of each measuring point. According to the method, the problems of insensitive response to the turn-to-turn short circuit fault of the inner layer encapsulation and low positioning precision of a traditional method are solved, and a high-reliability technical scheme is provided for fault detection of the dry-type air-core reactor.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring technology, specifically a method for locating inter-turn short-circuit faults in dry-type reactors based on magnetic field direction angle. Background Technology

[0002] Dry-type air-core reactors are crucial equipment in power systems, primarily used for limiting short-circuit currents and compensating for reactive power. Due to their long-term operation under high voltage and high current conditions, their windings are subjected to various factors such as electrodynamics, thermal stress, and mechanical vibration, leading to aging and embrittlement of the inter-turn insulation, ultimately causing inter-turn short-circuit faults. Statistics show that inter-turn short circuits account for over 60% of reactor failures, seriously threatening the safe and stable operation of power systems.

[0003] Currently, numerous diagnostic methods exist for inter-turn short-circuit faults in dry-type air-core reactors, encompassing electrical parameter analysis, vibration signal analysis, infrared thermal imaging detection, and detection coil methods. However, these methods all have limitations in practical applications, resulting in unsatisfactory fault detection and difficulty in achieving precise fault location. Specifically:

[0004] Electrical parameter analysis methods identify faults by monitoring changes in parameters such as voltage, current, and impedance of reactors. However, during power system operation, various factors such as load changes and system faults can cause fluctuations in electrical parameters, interfering with the accuracy of fault diagnosis. Vibration signal analysis methods locate faults based on changes in winding vibration characteristics. However, this method has extremely stringent requirements for sensor installation, requiring precise installation at vibration-sensitive points on the windings. Moreover, in complex environments such as substations, vibrations from external equipment can severely interfere with measurement signals, making fault feature extraction difficult. Traditional magnetic field analysis methods rely on changes in magnetic field strength amplitude to detect faults. However, under normal operating conditions and short-circuit conditions, especially in the initial stage of a short circuit, the difference in magnetic field amplitude is small, making accurate fault location difficult.

[0005] Furthermore, existing methods have significant shortcomings in sensor layout optimization and fault feature extraction: In terms of sensor layout, most adopt a uniform distribution approach, lacking targeted analysis of the reactor's magnetic field distribution characteristics and fault-sensitive areas, resulting in insufficient collection of magnetic field information in fault-sensitive areas. Regarding fault feature extraction, current methods mainly select features such as magnetic field strength amplitude and vibration frequency. These features fail to effectively reflect the local magnetic field distortion characteristics at the short-circuit point and are difficult to distinguish subtle differences in short circuits at different locations.

[0006] To address the problems existing in the prior art, this invention proposes a method for locating inter-turn short-circuit faults in dry-type air-core reactors based on magnetic field direction angle. This method optimizes the sensor layout by deeply analyzing the changing characteristics of the magnetic field direction angle and utilizing the difference in magnetic field direction angle between short-circuit and normal operating conditions to achieve precise fault location. It aims to solve the problems of low location accuracy and weak anti-interference capability in existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide a method for locating inter-turn short-circuit faults in dry-type air-core reactors based on the magnetic field direction angle. By utilizing the changing characteristics of the magnetic field direction angle at different measurement points during an inter-turn short circuit, the method can locate the short-circuit point of the reactor, providing a reference for reactor fault detection and maintenance.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] A method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle, the detection method comprising:

[0010] Step S1: Obtain radial and axial magnetic field component data for the specified outer region under different working conditions;

[0011] Step S2: Divide the measurement area according to the reactor structure and magnetic field distribution characteristics;

[0012] Step S3: Based on the measurement area divided in Step S2 and the initial magnetic field components in the radial and axial magnetic field component data obtained in Step S1, select the optimal measurement area under different working conditions.

[0013] Step S4: Calculate the magnetic field direction angle of the optimal measurement area under different working conditions selected in Step S3;

[0014] Step S5: Based on the magnetic field direction angle of the optimal measurement area under different working conditions calculated in Step S4 and the variation characteristics of the magnetic field direction angle of the measurement point under different working conditions, formulate a sensor layout scheme and determine each measurement point;

[0015] Step S6: Fault location is achieved by analyzing the difference in magnetic field direction angle between short-circuit and normal operating conditions at each measurement point.

[0016] Optionally, step S1 specifically includes the following method for obtaining the magnetic field component data: building a two-dimensional axisymmetric model of a dry-type air-core reactor, and obtaining the radial and axial magnetic field strengths under normal operating conditions and inter-turn short-circuit conditions at different locations by adjusting the short-circuit point position; and improving the reactor model by combining simulation and experimental measurement data.

[0017] Optionally, in step S2, the measurement area is divided according to the following rule: based on the characteristic that the radial magnetic field and the axial magnetic field are equal at a certain distance from the outermost layer of the dry air reactor under different operating conditions, the measurement area is set in any direction outside the reactor according to the preset radial distance and the full axial height range.

[0018] Optionally, in step S2, the specific method for dividing the measurement area is as follows:

[0019] Using the outermost encapsulated surface of the reactor as a reference, measurement lines with radial distances of d0, d0+d, d0+2d, ..., d0+nd (unit: cm) are set in any direction, covering the entire height h of the reactor (from the bottom end to the top end of the encapsulation).

[0020] Define the region at a radial distance d0 and an axial height of h as l0. Similarly, define the region at a radial distance d0+d and an axial height of h as l1, and the region at a radial distance d0+nd and an axial height of h as l. n ;

[0021] Where d0 is the preset minimum radial measurement distance, d0+nd is the preset maximum radial measurement distance, d is the radial step size, and the divided measurement area covers the entire height of the reactor winding and the effective radial detection range.

[0022] Optionally, in step S3, the specific process of selecting the optimal measurement area is as follows:

[0023] For different working conditions, based on the radial and axial magnetic field component data obtained in step S1, the l0, l1, ..., l values ​​divided in step S2 are obtained respectively. n The real parts of the radial and axial magnetic fields of the region are taken as absolute values; the real parts of the radial and axial magnetic fields obtained in the simulation are the instantaneous value components at a specific moment defined by the reference phase zero point (t=0) when the dry air reactor is operating normally.

[0024] The optimal measurement area is selected based on the absolute values ​​of the real parts of the radial and axial magnetic fields in different regions under different working conditions.

[0025] Optionally, in step S4, the magnetic field direction angle is (θ) the angle between the magnetic field vector and the radial direction (r-axis) in the r-z plane:

[0026]

[0027] In the formula, θ is the direction angle of the magnetic field, and B r B is the radial component of the magnetic field. z This represents the axial component of the magnetic field; in actual measurements, fiber optic sensors (which can only detect non-negative values) are used, and the absolute value of the ratio of the axial to radial components is taken.

[0028] Optionally, in step S5, formulating the sensor layout scheme includes the following steps:

[0029] a. Short - circuit point setting: Short - circuit turns are respectively set in the innermost layer, middle layer and outermost layer of the dry - type air - core reactor. The positions of the short - circuit turns include the central turn and any 1 to several turns in the upper part.

[0030] b. Magnetic - field direction - angle calculation: Obtain the radial magnetic field and axial magnetic field in the optimal measurement area under different working conditions, and calculate the corresponding magnetic - field direction angles.

[0031] c. Analysis of change characteristics: At the initial moment, there are differences in the distribution of magnetic - field direction angles and the offset law of extreme - value points between normal working conditions and short - circuit working conditions. Specifically, when the central turn is short - circuited, the heights of the measurement points with a magnetic - field direction angle of 0° are b2 and b4, those with a magnetic - field direction angle of 90° are b1, b3, and b5, and the points with the same direction angle in normal and short - circuit working conditions are b6 and b7 (b1 < b6 < b2 < b3 < b4 < b7 < b5); when the top - most turn is short - circuited, the height of the 0° point is c2, the height of the 90° point is c1, and the same points are c3 and c4 (c1 < c3 < c2 < c4). And as the short - circuit turn rises, b2 tends to c2 and b1 tends to c1.

[0032] d. Selection of layout points: Based on the above analysis, 10 measurement points are set in the area where the magnetic - field direction angle changes significantly (numbered 1 - 10 from bottom to top). Specifically, 1 is set at each of the positions 5 - 10 cm below b1 and above b5, 2 are set at each of the positions 5 - 10 cm above and below c1 and c2, and 4 are set at intervals of 10 - 20 cm above and below the center line.

[0033] Optionally, in step S6, the difference in the magnetic - field direction angles between the short - circuit working condition and the normal working condition at different measurement points is Δθ = θ 短路 −θ 正常 ;

[0034] Optionally, step S6 realizes fault location by analyzing the difference in the magnetic - field direction angles between the short - circuit working condition and the normal working condition at each measurement point, including the following steps:

[0035] a. Fault diagnosis: Based on measurement points 4 - 7 for fault diagnosis. If the difference between the magnetic - field direction angle obtained at the measurement point and the magnetic - field direction at the initial moment of the previous cycle exceeds the set threshold, it is judged that a fault has occurred.

[0036] b. Division of short - circuit height: The axial direction of the reactor is divided into the upper part, the central point and the lower part.

[0037] c. Short-circuit height location: First, determine the center point short circuit. If the ratio of the absolute value of the difference between the magnetic field direction angle of any lower measurement point (e.g., measurement point 1 and measurement point 10 are symmetrical) and the sum of the absolute values ​​of the magnetic field direction angles of the upper symmetrical measurement points is less than 1%, then the fault occurs in the center of the reactor. If the Δθ of measurement points 1, 2, and 3 is non-negative, or the Δθ of measurement points 1 and 2 is non-negative and increasing, and measurement points 9 and 10 have negative values, or the Δθ of measurement points 1, 2, 9, and 10 is all greater than 0, and the Δθ of measurement point 2 is greater than the Δθ of measurement point 9, then the short circuit point is in the upper part. If the Δθ of measurement points 8, 9, and 10 is non-negative, or the Δθ of measurement points 9 and 10 is non-negative and decreasing, and measurement points 1 and 2 have negative values, or the Δθ of measurement points 1, 2, 9, and 10 is all greater than 0, and the Δθ of measurement point 2 is less than the Δθ of measurement point 9, then the short circuit point is in the lower part.

[0038] d. Short-circuit location: For a short circuit in the upper part, the location is determined based on the Δθ values ​​of measurement points 1 and 3; for a short circuit in the lower part, the location is determined based on the Δθ values ​​of measurement points 8 and 10; for a short circuit at the center point in the middle, the location can be determined using either the Δθ values ​​of measurement points 1 and 3 or the Δθ values ​​of measurement points 8 and 10. Taking a short circuit on a certain turn in the upper part as an example, the location of the short circuit is specifically determined by first using measurement point 1 to filter the short circuit location. When short circuits occur at different locations, the Δθ values ​​of measurement point 1 may be equal. Therefore, the Δθ value of measurement point 3 is used for secondary filtering to locate the short circuit point. If equal values ​​still exist, the Δθ value of measurement point 2 can be added for tertiary filtering.

[0039] The present invention has the following technical effects:

[0040] Based on the changing characteristics of the magnetic field direction angle of the outer side of the dry-type air-core reactor before and after an inter-turn short circuit, this invention proposes a layout method for the magnetic field sensor on the outer side of the dry-type air-core reactor. This method can locate the short circuit point by measuring the difference in the magnetic field direction angle before and after the short circuit at multiple measurement points, providing a reference for fault diagnosis and maintenance of the reactor. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A flowchart of a method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle, provided for an embodiment of the present invention;

[0043] Figure 2 A measurement area diagram of a dry-type air-core reactor provided in an embodiment of the present invention;

[0044] Figure 3 The graph showing the change in magnetic field direction angle in different measurement areas when the 43rd layer and 92 turns are short-circuited is provided for an embodiment of the present invention.

[0045] Figure 4 A graph showing the absolute values ​​of the real parts of the radial and axial magnetic fields in a selected measurement area during normal operation of a dry-type air-core reactor, as provided in an embodiment of the present invention.

[0046] Figure 5 This is a graph showing the change in the magnetic field direction angle of the selected measurement area when different turns of the 43rd layer are short-circuited, provided as an embodiment of the present invention.

[0047] Figure 6 An orientation diagram of the array arrangement of the fiber optic magnetic field measurement sensor provided in an embodiment of the present invention.

[0048] Figure 7 This invention provides a flowchart for fault location based on the magnetic field direction angle difference Δθ.

[0049] Figure 8 The graph shows the change in the magnetic field direction angle of the selected measurement area when different turns of the first layer are short-circuited, as provided in the embodiments of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] The purpose of this invention is to provide a method for locating inter-turn short-circuit faults in dry-type air-core reactors based on magnetic field direction angle. This method can locate the short-circuit point by analyzing the difference in magnetic field direction angles before and after the short circuit at multiple measurement points. Figure 1 As shown, the method includes the following steps:

[0052] Step S1: Obtain radial and axial magnetic field component data of the specified outer region under different working conditions;

[0053] First, a two-dimensional axisymmetric model of the dry-type air-core reactor was built. The dry-type air-core reactor was cast with epoxy resin. The inter-turn short-circuit test was more ideal for the outermost winding, but it was more difficult for other layers and the test was more complicated. Therefore, simulation was used.

[0054] Then, by adjusting the short-circuit point location, the radial magnetic field strength and axial magnetic field strength under normal operating conditions and inter-turn short-circuit conditions at different locations are obtained;

[0055] Finally, the reactor model was improved by combining simulation and experimental measurement data.

[0056] Step S2: Divide the measurement area according to the reactor structure and magnetic field distribution characteristics;

[0057] The measurement area is divided according to the following rules: based on the characteristic that the radial magnetic field and the axial magnetic field are equal at a certain distance from the outermost layer of the dry air reactor under different operating conditions, the measurement area is set in any direction outside the reactor according to the preset radial distance and the full axial height range.

[0058] The sensor needs to be perpendicular to the rz plane formed by the radial and axial directions of the reactor to ensure accurate acquisition of the radial and axial magnetic field components and avoid measurement errors caused by angular deviations.

[0059] Step S3: Based on the measurement area divided in step S2 and the initial magnetic field components in the radial and axial magnetic field component data obtained in step S1, select the optimal measurement area.

[0060] The specific method for dividing the measurement area is as follows:

[0061] Using the outermost surface of the reactor as a reference, measuring lines with radial distances of 20, 25, 30, ..., 20+5n (unit: cm) are set in any direction, covering the entire height of the reactor (1.7878m) axially (from the bottom to the top of the enclosure).

[0062] like Figure 2 As shown, the region with a radial distance of 20cm and an axial height of 1.7878m is defined as l0. Similarly, the region with a radial distance of 25cm and an axial height of 1.7878m is defined as l1, and the region with a radial distance of 30cm and an axial height of 1.7878m is defined as l2.

[0063] The preset minimum radial measurement distance is 20cm, the preset maximum radial measurement distance is 30cm, and the radial step size is 5cm. The divided measurement area covers the entire height of the reactor winding and the effective radial detection range. If the preset distance is too close, it will affect the reactor's heat dissipation; if it is too far, it will be easily affected by other interference sources.

[0064] For different working conditions, the real parts of the radial and axial magnetic fields in regions l0, l1, and l2 are obtained and their absolute values ​​are taken, such as... Figure 3 As shown; the real parts of the radial and axial magnetic fields obtained in the simulation are the instantaneous value components at a specific moment defined by the reference phase zero point (t=0) when the dry air reactor is operating normally;

[0065] The optimal measurement area is selected based on the absolute values ​​of the real parts of the radial and axial magnetic fields in different regions under different working conditions.

[0066] Step S4: Calculate the magnetic field direction angle of the optimal measurement area under different working conditions selected in Step S3;

[0067] Using l0 as the optimal measurement area, obtain the radial and axial magnetic fields of the optimal measurement area during normal operation and take their absolute values, such as... Figure 4 As shown. Then, short-circuit turns are set at layers 1, 22, and 43 respectively. Taking layer 43 as an example, turns 92, 138, and 183 are selected as short-circuit turns. The magnetic field direction angle of the optimal measurement area when short-circuiting between turns at different locations is shown in the figure. Figure 5 As shown.

[0068] The magnetic field direction angle is (θ) the angle between the magnetic field vector and the radial direction (r-axis) in the r−z plane:

[0069]

[0070] In the formula, θ is the direction angle of the magnetic field, and B r B is the radial component of the magnetic field. z This represents the axial component of the magnetic field; in actual measurements, fiber optic sensors (which can only detect non-negative values) are used, and the absolute value of the ratio of the axial to radial components is taken.

[0071] Step S5: Based on the magnetic field direction angle of the optimal measurement area under different working conditions calculated in Step S4 and the variation characteristics of the magnetic field direction angle of the measurement point under different working conditions, formulate a sensor layout scheme and determine each measurement point;

[0072] The formulation of the sensor layout scheme includes the following steps:

[0073] a. Short-circuit point setting: Short-circuit turns are set in the innermost, middle and outermost layers of the dry-type air-core reactor. The short-circuit turn positions include the center turn and one to several turns in the upper part.

[0074] b. Calculation of magnetic field direction angle: Obtain the radial and axial magnetic fields within the optimal measurement area under different working conditions, and calculate the corresponding magnetic field direction angle;

[0075] c. Analysis of Variation Characteristics: The distribution of the magnetic field direction angle and the shift of extreme points differ between the normal operating condition and the short-circuit operating condition at the initial moment. Specifically, as follows: Figure 5 As shown in (a), when the center turn is short-circuited, the heights of the measurement points with a magnetic field direction angle of 0° are 0.64m and 1.16m, and those with a direction angle of 90° are 0.16m, 0.9m, and 1.64m. The points with the same direction angle under normal and short-circuit conditions are 0.32m and 1.48m. When the highest turn is short-circuited, the height of the 0° point is 1.46m, the 90° point is 0.43m, and the points with the same direction angle are 0.61m and 1.72m.

[0076] d. Selection of measurement points: Based on the above analysis, 10 measurement points (numbered 1-10 from bottom to top) are set in the area where the magnetic field direction angle changes significantly. Specifically: one point is set at the lower part of 0.16m and 5-10cm above 1.64m, i.e., at 0.1m and 1.7m; two points are set at the upper and lower parts of 0.32m and 1.48m, i.e., at 0.3m and 0.5m, and at 1.3m and 1.5m; and four points are set every 10-20cm above and below the center line, i.e., at 0.7m and 0.8m, and at 1m and 1.1m. Figure 6 As shown.

[0077] Step S6: Fault location is achieved by analyzing the difference in magnetic field direction angle between short circuit and normal operating conditions at each measurement point.

[0078] The difference in magnetic field direction angle between short-circuit conditions and normal conditions at different measurement points is Δθ = θ 短路 −θ 正常 Fault location is based on the difference in magnetic field direction angle Δθ, such as Figure 7 As shown, it includes the following steps:

[0079] a. Fault diagnosis: Fault diagnosis is performed based on measurement points 4-7. If the difference between the magnetic field direction angle obtained from the measurement point and the magnetic field direction at the initial moment of the previous cycle exceeds the set threshold, it is judged that a fault has occurred.

[0080] b. Short-circuit height division: The reactor is axially divided into upper part, center point and lower part;

[0081] c. Short-circuit height location: First, determine the center point short circuit. If the ratio of the absolute value of the difference between the magnetic field direction angle of any lower measurement point (e.g., measurement point 1 and measurement point 10 are symmetrical) and the sum of the absolute values ​​of the magnetic field direction angles of the upper symmetrical measurement points is less than 1%, then the fault occurs in the center of the reactor. If the Δθ of measurement points 1, 2, and 3 is non-negative, or the Δθ of measurement points 1 and 2 is non-negative and increasing, and measurement points 9 and 10 have negative values, or the Δθ of measurement points 1, 2, 9, and 10 is all greater than 0, and the Δθ of measurement point 2 is greater than the Δθ of measurement point 9, then the short circuit point is in the upper part. If the Δθ of measurement points 8, 9, and 10 is non-negative, or the Δθ of measurement points 9 and 10 is non-negative and decreasing, and measurement points 1 and 2 have negative values, or the Δθ of measurement points 1, 2, 9, and 10 is all greater than 0, and the Δθ of measurement point 2 is less than the Δθ of measurement point 9, then the short circuit point is in the lower part.

[0082] d. Short circuit location: such as Figure 8 As shown, when the short circuit occurs on the upper side of the reactor, the changes in Δθ at measurement points 1 and 3 follow a certain pattern, that is, it decreases as the short circuit location increases. Furthermore, this is combined with... Figure 5As shown, when the short-circuit point shifts from the inside to the outside, the change in Δθ also follows a certain pattern, that is, it increases as the short-circuit position moves outward. Therefore, for a short circuit in the upper part, the location is determined based on the Δθ of measurement points 1 and 3; similarly, for a short circuit in the lower part, the location is determined based on the Δθ of measurement points 8 and 10. For a short circuit at the center point in the middle part, the location can be determined using either the Δθ of measurement points 1 and 3 or the Δθ of measurement points 8 and 10. Taking a short circuit in a certain turn in the upper part as an example, the location of the short circuit position is specifically determined by first using measurement point 1 to filter the short circuit position. When short circuits occur at different positions, the Δθ of measurement point 1 may be equal. Therefore, the Δθ of measurement point 3 is used for secondary filtering to locate the short circuit point. If equal values ​​still exist, the Δθ of measurement point 2 can be added for tertiary filtering.

[0083] This invention utilizes the high sensitivity and significant variation characteristics of magnetic field direction angle to inter-turn short-circuit faults, combined with an optimal sensor layout scheme based on the selection of the best measurement area, to solve the problems of insensitive response and low positioning accuracy of inter-turn short-circuit faults caused by the reliance on magnetic field amplitude in traditional methods. Specific beneficial effects include:

[0084] 1. High-sensitivity inter-turn short circuit fault detection: By replacing the traditional magnetic field amplitude with the magnetic field direction angle θ, the magnetic field distortion generated when an inter-turn short circuit occurs at any position of the dry reactor can be captured, thus achieving high-sensitivity inter-turn short circuit fault early warning.

[0085] 2. Precise positioning capability: Based on the optimal measurement area selection (step S3) and the 10-point sensor array layout (step S5), combined with Δθ (θ 短路 −θ 正常 By determining the sign and size relationship of the symbols, the axial height and radial layer position of the short-circuit point can be accurately located with a positioning error of less than 1%.

[0086] 3. Strong anti-interference capability: The optimal region is selected by the absolute value of the real part of the magnetic field component at the initial moment (step S3), which reduces the interference of the external environment on the magnetic field measurement and improves the reliability under complex working conditions.

[0087] 4. Sensor layout optimization: Sensors are placed in areas with significant changes in magnetic field direction angle (such as extreme points of 0° / 90°, and points with the same conditions under normal / short circuit conditions) to reduce redundant measurement points, lower costs, and improve data acquisition efficiency.

[0088] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle, characterized in that, The method includes: Step S1: Obtain radial and axial magnetic field component data for the specified outer region under different working conditions; Step S2: Divide the measurement area according to the reactor structure and magnetic field distribution characteristics; Step S3: Based on the measurement area divided in Step S2 and the initial magnetic field components in the radial and axial magnetic field component data obtained in Step S1, select the optimal measurement area under different working conditions. Step S4: Calculate the magnetic field direction angle of the optimal measurement area under different working conditions selected in Step S3; Step S5: Based on the magnetic field direction angle of the optimal measurement area under different working conditions calculated in Step S4 and the variation characteristics of the magnetic field direction angle of the measurement point under different working conditions, formulate a sensor layout scheme and determine each measurement point; Step S6: Fault location is achieved by analyzing the difference in magnetic field direction angle between short-circuit and normal operating conditions at each measurement point.

2. The method for locating inter-turn short-circuit faults in dry-type air-core reactors based on magnetic field direction angle according to claim 1, characterized in that, Step S1 specifically includes: building a two-dimensional axisymmetric model of a dry-type air-core reactor, and obtaining the radial and axial magnetic field strengths under normal operating conditions and inter-turn short-circuit conditions at different locations by adjusting the short-circuit point position.

3. The method for locating inter-turn short-circuit faults in dry-type air-core reactors based on magnetic field direction angle according to claim 1, characterized in that, In step S2, the measurement area is divided according to the following rules: based on the characteristic that the radial magnetic field and the axial magnetic field are equal at a certain distance from the outermost layer of the dry air reactor under different operating conditions, the measurement area is set in any direction outside the reactor according to the preset radial distance and the full axial height range.

4. The method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle according to claim 1, wherein in step S2, the specific division of the measurement area is as follows: Using the outermost encapsulated surface of the reactor as a reference, measurement lines with radial distances of d0, d0+d, d0+2d, ..., d0+nd are set in any direction, covering the entire height h of the reactor axially; Define the region at a radial distance d0 and an axial height of h as l0. Similarly, define the region at a radial distance d0+d and an axial height of h as l1, and the region at a radial distance d0+nd and an axial height of h as l. n ; Where d0 is the preset minimum radial measurement distance, d0+nd is the preset maximum radial measurement distance, d is the radial step size, and the divided measurement area covers the entire height of the reactor winding and the effective radial detection range.

5. The method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle according to claim 4, characterized in that, In step S3, the specific process of selecting the optimal measurement area is as follows: For different working conditions, based on the radial and axial magnetic field component data obtained in step S1, the l0, l1, ..., l values ​​divided in step S2 are obtained respectively. n The real parts of the radial and axial magnetic field components of the region are taken as absolute values; the real parts of the radial and axial magnetic fields obtained in the simulation are the instantaneous value components at a specific moment defined by the reference phase zero point when the dry air reactor is operating normally. The optimal measurement area is selected based on the absolute values ​​of the real parts of the radial and axial magnetic fields in different regions under different working conditions.

6. The method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle according to claim 1, characterized in that, In step S4, the magnetic field direction angle is the angle between the magnetic field vector in the r−z plane and the radial r-axis: ； In the formula, θ is the direction angle of the magnetic field, and B r B is the radial component of the magnetic field. z This represents the axial component of the magnetic field; in actual measurements, fiber optic sensors are used, and the absolute value of the ratio of the axial to radial components is taken.

7. The method for locating inter-turn short-circuit faults in dry-type air-core reactors based on magnetic field direction angle according to claim 1, characterized in that, In step S5, the formulation of the sensor layout scheme includes the following steps: a. Short-circuit point setting: Short-circuit turns are set in the innermost, middle and outermost layers of the dry-type air-core reactor. The short-circuit turn positions include the center turn and one to several turns in the upper part. b. Calculation of magnetic field direction angle: Obtain the radial and axial magnetic fields within the optimal measurement area under different working conditions, and calculate the corresponding magnetic field direction angle; c. Analysis of variation characteristics: At the initial moment, under normal and short-circuit conditions, there are differences in the magnetic field direction angle distribution and the offset law of extreme points. Specifically, when the center turn is short-circuited, the heights of the measurement points with a magnetic field direction angle of 0° are b2 and b4, and those with a magnetic field direction angle of 90° are b1, b3, and b5. The points with the same direction angle under normal and short-circuit conditions are b6 and b7, where b1 < b6 < b2 < b3 < b4 < b7 < b5; when the top turn is short-circuited, the height of the 0° point is c2, the height of the 90° point is c1, and the same points are c3 and c4, where c1 < c3 < c2 < c4. And as the short-circuited turn rises, b2 tends to c2 and b1 tends to c1. d. Selection of layout points: Based on the results of the variation characteristics analysis, 10 measurement points are set in the region where the magnetic field direction angle changes significantly. Specifically, one is set at 5 - 10 cm below b1 and 5 - 10 cm above b5 respectively, two are set at 5 - 10 cm above and below c1 and c2 respectively, and four are set at intervals of 10 - 20 cm above and below the center line.

8. The method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle according to claim 7, wherein the difference in magnetic field direction angle between the short-circuit condition and the normal condition at different measurement points in step S6 is Δθ = θ 短路 −θ 正常 .

9. The method for locating inter-turn short-circuit faults in a dry-type air-core reactor based on magnetic field direction angle according to claim 8, characterized in that, Step S6 realizes fault location by analyzing the differences in the magnetic field direction angles of each measurement point under short-circuit and normal conditions, including the following steps: a. Fault diagnosis: Based on measurement points 4 - 7 for fault diagnosis. If the difference between the magnetic field direction angle obtained from the measurement point and the magnetic field direction at the initial moment of the previous cycle exceeds the set threshold, it is judged that a fault has occurred. b. Division of short-circuit height: The axial direction of the reactor is divided into the upper part, the center point, and the lower part. c. Location of short-circuit height: If the ratio of half of the sum of the absolute values of the differences in the magnetic field direction angles between any measurement point in the lower part and the symmetric measurement point in the upper part is within 1%, the fault occurs in the center of the middle part of the reactor; if the Δθ of measurement points 1, 2, and 3 is non-negative, or the Δθ of measurement points 1 and 2 is non-negative and increasing, and there are negative values at measurement points 9 and 10, or the Δθ of measurement points 1, 2, 9, and 10 are all greater than 0, and the Δθ of measurement point 2 is greater than the Δθ of measurement point 9, the short-circuit point is in the upper part; if the Δθ of measurement points 8, 9, and 10 is non-negative, or the Δθ of measurement points 9 and 10 is non-negative and decreasing, and there are negative values at measurement points 1 and 2, or the Δθ of measurement points 1, 2, 9, and 10 are all greater than 0, and the Δθ of measurement point 2 is less than the Δθ of measurement point 9, the short-circuit point is in the lower part. d. Location of short-circuit position: When the upper part is short-circuited, it is located based on the Δθ of measurement points 1 and 3. When the lower part is short-circuited, it is located based on the Δθ of measurement points 8 and 10. When the middle center point is short-circuited, it can be located based on the Δθ of measurement points 1 and 3 and the Δθ of measurement points 8 and 10.

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