A method for simulating transformer winding deformation and axial displacement fault and processing oscillating wave signal

Abstract

The application discloses a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, and the system comprises a main body structure, a vibration device, an axial displacement device and a signal acquisition device; the device is manually placed in a suitable position inside the transformer winding, and then a transformer winding fault type to be simulated is selected; if winding deformation under current impact is to be simulated, a vibration piece is attached to the transformer winding inside; if winding axial displacement fault is to be simulated, a high pad tooth is inserted into the transformer winding, and the degree of winding axial displacement is controlled by controlling the force of pulling the pull handle. Secondly, different fault conditions are simulated at different positions, corresponding oscillation waveform data are collected for diagnosis and analysis, a fault coefficient is obtained by calculation, and the transformer winding fault position is known, so that the possibility of improving the accuracy and efficiency of transformer winding fault detection is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind power prediction, in particular to a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method. BACKGROUND

[0002] As the core hub of the power system, the mechanical integrity of the transformer winding is directly related to the stability and safety of power transmission. Mechanical faults such as winding deformation (such as axial deformation, twisting) and axial displacement are often caused by complex factors such as short-circuit current impact, vibration during transportation, long-term operation aging or temperature stress. If these faults are not discovered in time, they may gradually develop into winding insulation breakdown, partial discharge aggravation or even transformer burning, which may lead to large-scale power outage accidents and cause great losses to the society and economy and people's livelihood.

[0003] Traditional detection techniques such as frequency response analysis (FRA) are relatively sensitive to winding deformation, but have limited detection capability for axial displacement and are easily disturbed by external interference. Low-voltage short-circuit impedance method can reflect winding deformation, but the quantitative analysis precision is insufficient and it is difficult to identify slight faults. Offline detection methods cannot meet the real-time monitoring requirements because they require power outage, and online monitoring techniques face difficulties such as signal extraction and insignificant features. Compared with the above methods, the oscillation wave test technology injects a specific frequency oscillation voltage into the winding to excite the mechanical vibration response of the winding, which has the advantages of low test voltage, small damage to equipment, and rich mechanical characteristic information in the signal, and is suitable for online or offline detection. However, there are still many challenges in practical application: on the one hand, traditional winding fault simulation models (such as lumped parameter model or simplified mechanical model) cannot accurately reproduce the dynamic physical process of winding deformation and axial displacement, resulting in deviation between simulation results and actual fault characteristics; on the other hand, the oscillation wave signal is easily affected by environmental noise, electromagnetic interference, etc. during transmission, and the weak feature changes (such as frequency shift and amplitude attenuation) caused by faults are difficult to extract directly, and advanced signal processing algorithms (such as wavelet transform, deep learning, etc.) are needed to improve the sensitivity and accuracy of feature recognition.

[0004] Therefore, it is of great significance to develop a method that can accurately simulate the winding deformation and axial displacement fault mechanism and effectively process the oscillation wave signal to accurately identify the fault characteristics, in order to improve the reliability of transformer state evaluation and ensure the safe and stable operation of the power system. SUMMARY

[0005] The purpose of the present application is to provide a simulation method of winding deformation and axial displacement of transformer winding under current impact and a processing method of oscillation wave signal.

[0006] In order to solve the above technical purposes, the present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, comprising: a main body structure, a vibration device, an axial displacement device, and a signal acquisition device;

[0007] The main body structure comprises a pull handle, three pull arms, a fixing ring, a center column, a bottom ring, a sliding sleeve and three unfolding arms; one end of the three pull arms is connected with the pull handle, and the other end is connected with the sliding sleeve; the pull arms are evenly connected on the sliding sleeve; the sliding sleeve is directly sleeved on the center column; the three unfolding arms are connected with the sliding sleeve through connecting rods.

[0008] The vibration device comprises three vibration sheets, a motor, a rotating rod and two vibration devices; the three vibration sheets are connected with the three unfolding arms through shafts respectively; the motor drives the rotating rod and the two vibration devices to rotate; the rotating rod and the two vibration devices are both in the center column.

[0009] The axial displacement device comprises three heightening teeth; the three heightening teeth are connected with the three unfolding arms through shafts respectively.

[0010] The signal acquisition device is connected with one end of the transformer winding, and is used for obtaining the transformer oscillation wave waveform data under the fault condition.

[0011] Optionally, the high-voltage oscillation wave power supply system comprises a high-frequency high-voltage switch and a high-frequency high-voltage DC power supply; the high-frequency high-voltage switch, the high-frequency high-voltage DC power supply and the signal acquisition device are connected in series at two ends of the transformer winding; the high-frequency high-voltage switch is used for controlling the high-frequency high-voltage DC power supply to periodically charge and discharge the transformer winding.

[0012] The present application also provides a transformer winding fault analysis method, comprising:

[0013] 1. Signal model establishment

[0014] 2. Band-pass filter preprocessing

[0015] 3. Hilbert transform demodulation

[0016] 4. Effective value (RMS) calculation

[0017] 5. Kurtosis calculation

[0018] 6. Short-time Fourier transform (STFT)

[0019] 7. Autocorrelation function estimation frequency

[0020] 8. Least square parameter fitting

[0021] 9. Phase unmixing and characteristic parameter fusion to obtain fault coefficient

[0022] 10. Result verification and optimization

[0023] Optionally, the failure coefficient is represented as:

[0024]

[0025] C feature : comprehensive characteristic parameter, obtained by weighted fusion of effective value (RMS), kurtosis and phase change rate α, β, γ: weight coefficient (adjust the contribution of each feature according to actual requirements).

[0026] Compared with the prior art, the present application has at least the following beneficial effects:

[0027] The present application does not need to perform long-time current impact on the transformer winding, and the deformation of the transformer winding caused by the current impact is simulated by adding physical vibration to the transformer winding; different positions are simulated by changing the position of the vibration piece inside the winding, and stepless axial displacement fault simulation of the transformer winding can be realized by using the high tooth; different positions are simulated by changing the position of the high tooth inside the winding, and stepless axial displacement under different fault states can be simulated by changing the depth of the high tooth into the transformer winding, and the state of the transformer winding is obtained by using high-voltage oscillation wave technology, thereby providing a basis for the operation and maintenance of the transformer. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a front view of the transformer winding fault simulation and detection system in the embodiment of the present application

[0029] Figure 2 is a bottom view of the transformer winding fault simulation and detection system in the embodiment of the present application

[0030] Figure 3 is an oscillation device of the transformer winding fault simulation and detection system in the embodiment of the present application

[0031] Figure 4 is a schematic diagram of transformer winding fault detection in the embodiment of the present application.

[0032] In the figure, 1, pull handle; 2, first pull arm; 3, second pull arm; 4, fixed ring; 5, first unfolding arm; 6, second unfolding arm; 7, third unfolding arm; 8, sliding sleeve; 9, center column; 10, first heightening tooth; 11, second heightening tooth; 12, third heightening tooth; 13, first vibration piece; 14, second vibration piece; 15, third vibration piece; 16, bottom ring; 17, third pull arm; 18, motor; 19, rotating rod; 20, first vibrator; 21, second vibrator; 22, transformer winding; 23, pressure vibration wave power system; 24, head end lead-out wire; 25, tail end lead-out wire; 26, signal acquisition device. DETAILED DESCRIPTION

[0033] The transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method of the present application will be described in more detail below with reference to the accompanying drawings, in which the preferred embodiments of the present application are shown, it should be understood that those skilled in the art can modify the present application described herein while still achieving the advantageous effects of the present application. Therefore, the following description should be understood as a broad knowledge to those skilled in the art, and not as a limitation of the present application.

[0034] The present application will be described in more detail in the following paragraphs with reference to the accompanying drawings. The advantages and features of the present application will be more apparent according to the following description. It should be noted that the drawings are very simplified and use non-precise proportions, only for the purpose of facilitating, clarifying the purpose of assisting the description of the embodiments of the present application.

[0035] Example one (simulate winding deformation of different positions of transformer under current impact)

[0036] The present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, please refer to Figure 1 - Figure 3 .

[0037] In one example, three pull arms are evenly connected between the pull handle 1 and the sliding sleeve 8, which are the first pull arm 2, the second pull arm 3 and the third pull arm 17, and the sliding sleeve 8 is directly sleeved on the center column 9. Three unfolding arms are connected with the sliding sleeve through connecting rods, and the three unfolding arms are the first unfolding arm 5, the second unfolding arm 6 and the third unfolding arm 7. Put the device into the appropriate position inside the transformer winding 22.

[0038] The pulling handle 1 pulls up the sliding sleeve 8 through the first pulling arm 2, the second pulling arm 3 and the third pulling arm 17. The sliding sleeve 8 drives the first unfolding arm 5, the second unfolding arm 6 and the third unfolding arm 7 to unfold through the rotating shaft. The first vibration piece 13, the second vibration piece 14 and the third vibration piece 15 are manually adjusted to be close to the inner wall of the transformer winding 22. The motor 18 is directly connected with the rotating rod 19. The first vibrator 20 and the second vibrator 21 are connected in series on the rotating rod 19. When the motor 18 starts to rotate, the rotating rod 19, the first vibrator 20 and the second vibrator 21 are directly driven to rotate. The first vibrator 20 and the second vibrator 21 are not symmetrical, and when they rotate, vibration is generated. The vibration is transmitted to the sliding sleeve 8 through the central column 9 and then transmitted to the three vibration pieces through the three unfolding arms. Finally, the three vibration pieces act on the inner wall of the transformer winding 22, so that the winding deformation of the transformer at different positions under current impact is simulated.

[0039] Example two (simulating transformer winding axial displacement fault)

[0040] The present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, please refer to Figure 1 Figure 2 .

[0041] In one of the examples, the three pulling arms are evenly connected between the pulling handle 1 and the sliding sleeve 8, which are the first pulling arm 2, the second pulling arm 3 and the third pulling arm 17. The sliding sleeve 8 is directly sleeved on the central column 9. The three unfolding arms are connected with the sliding sleeve through connecting rods, and the three unfolding arms are the first unfolding arm 5, the second unfolding arm 6 and the third unfolding arm 7. The device is placed in the appropriate position inside the transformer winding 22.

[0042] The pulling handle 1 pulls up the sliding sleeve 8 through the first pulling arm 2, the second pulling arm 3 and the third pulling arm 17. The sliding sleeve 8 drives the first unfolding arm 5, the second unfolding arm 6 and the third unfolding arm 7 to unfold through the rotating shaft. The first vibration piece 13, the second vibration piece 14 and the third vibration piece 15 are manually adjusted to be close to the inner wall of the transformer winding 22. The motor 18 is directly connected with the rotating rod 19. The first vibrator 20 and the second vibrator 21 are connected in series on the rotating rod 19. When the motor 18 starts to rotate, the rotating rod 19, the first vibrator 20 and the second vibrator 21 are directly driven to rotate. The first vibrator 20 and the second vibrator 21 are not symmetrical, and when they rotate, vibration is generated. The vibration is transmitted to the sliding sleeve 8 through the central column 9 and then transmitted to the three vibration pieces through the three unfolding arms. Finally, the three vibration pieces act on the inner wall of the transformer winding 22, so that the winding deformation of the transformer at different positions under current impact is simulated.

[0043] Example three (obtaining the oscillation wave of the winding after simulating the transformer winding fault)

[0044] ​The embodiment of the present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, based on the two transformer winding fault simulations provided in embodiment one and two, including the following steps:

[0045] The transformer winding after the simulated fault is obtained through example one or example two, and then the oscillation wave signals corresponding to different fault conditions at different positions of the transformer winding 1 are obtained.

[0046] Specifically,

[0047] S11, the first end of the transformer winding 22 is connected to the first end of the wire 24, and the other end of the wire is connected to the second end of the wire 24, and the other end of the wire is connected to the second end of the wire 25;

[0048] S12, the wire connected to the first end of the transformer winding 22 is connected to the high-frequency high-voltage DC power supply, and the high-frequency high-voltage switch is periodically operated, and the transformer winding 22 is periodically charged and discharged;

[0049] S13, the above process is repeated to obtain the transformer oscillation wave form data under different fault conditions at different positions through the signal acquisition device 26.

[0050] Embodiment four (processing the obtained oscillation wave signal)

[0051] The embodiment of the present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method, based on the transformer winding fault simulation provided in embodiment one or embodiment two and the oscillation wave form data obtained by using the transformer winding fault generation and detection method provided in embodiment three, including the following steps:

[0052] 1. Signal model establishment

[0053] The obtained oscillation wave signal is a noise-like sinusoidal signal:

[0054] x(t)=A sin(2πft+φ)+n(t)

[0055] Wherein, A is the amplitude, f is the frequency, φ is the initial phase, and n(t) is the Gaussian white noise.

[0056] 2. Band-pass filter preprocessing

[0057] The band-pass filter is designed, and the transfer function is:

[0058]

[0059] Wherein, fc is the center frequency, B is the bandwidth, and Q is the quality factor. The filtered signal is:

[0060]

[0061] where, is the inverse Fourier transform. X(f): Fourier transform of the original signal x(t).

[0062] 3. Hilbert transform demodulation

[0063] Construct the analytic signal by Hilbert transform:

[0064]

[0065] where, denotes the Hilbert transform. The signal envelope is:

[0066]

[0067] 4. Effective value (RMS) calculation

[0068]

[0069] where, T is the signal duration.

[0070] 5. Kurtosis calculation

[0071]

[0072] where, μ is the signal mean.

[0073] 6. Short-time Fourier transform (STFT)

[0074]

[0075] where, w(τ) is the window function (such as Hanning window).

[0076] 7. Autocorrelation function estimates frequency

[0077] The autocorrelation function is:

[0078]

[0079] Estimate the period by the main peak interval: T0 = 1 / f.

[0080] 8. Least squares parameter fitting

[0081] Estimate the parameters A, f, φ by minimizing the error function:

[0082]

[0083] Solve:

[0084]

[0085] 9. Phase unwrapping and feature parameter fusion

[0086] Unwrap the phase sequence φ(t) to obtain the continuous phase:

[0087] φ unwrapped (t) = φ(t) + 2πk(t) where k(t) is an integer correction term. The final fault coefficient is defined as:

[0088]

[0089] where α, β, γ are weight coefficients.

[0090] 10. Result verification and optimization

[0091] Verify the fitting accuracy by the root mean square error (RMSE):

[0092]

[0093] where, is the fitting signal.

[0094] According to the obtained C feature , the degree of transformer winding deformation fault can be known. Table 1 is the matching relationship between C feature and the fault position of the transformer winding:

[0095] Table 1

[0096] Transformer winding fault location C feature of the values Top fault C feature ≥455]]> Middle fault 100 < C feature <455 Bottom fault 55 < C feature <100]]

[0097] The present application provides a transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method. The device is manually placed in the appropriate position inside the transformer winding, and then the type of transformer winding fault to be simulated is selected. If the winding deformation under current impact is to be simulated, the vibration piece is selected to be attached to the inside of the transformer winding. If the axial displacement fault of the winding is to be simulated, the high pad tooth is selected to be inserted into the inside of the transformer winding, and the degree of winding axial displacement is controlled by controlling the force of the lifting handle. Secondly, the present application simulates different fault conditions at different positions, collects corresponding oscillation waveform data for diagnosis and analysis, calculates the fault coefficient, and knows the degree of transformer winding deformation fault, which provides the possibility for improving the accuracy and efficiency of transformer winding fault detection.

[0098] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for transformer winding deformation and axial displacement fault simulation and oscillating wave signal processing, characterized in that, The method comprises the following steps: a main body structure, a vibration device, an axial displacement device, a high-voltage oscillation wave power supply system, and a signal acquisition device; the main body structure comprises a pulling handle, three pulling arms, a fixing ring, a central column, a bottom ring, a sliding sleeve, and three unfolding arms; the pulling arms are evenly connected between the pulling handle and the sliding sleeve, and the sliding sleeve is sleeved outside the central column; the unfolding arms are connected with the sliding sleeve through connecting rods and can be unfolded or retracted with the movement of the sliding sleeve; the vibration device comprises three vibration pieces, a motor, a rotating rod, and two vibration devices; the vibration pieces are connected with the unfolding arms through rotating shafts, the motor drives the rotating rod and the asymmetrically arranged vibration devices to rotate, generates vibration, and transmits the vibration to the unfolding arms and the vibration pieces through the central column; the axial displacement device comprises three heightening teeth; the heightening teeth are connected with the unfolding arms through rotating shafts, the depth of the heightening teeth inserted into the winding is controlled by adjusting the pulling force of the pulling handle, and stepless axial displacement simulation is realized; the vibration pieces and the heightening teeth are manually adjusted to be close to the inner wall of the winding, and different position fault simulations are realized by the position change of the unfolding arms; the high-voltage oscillation wave power supply system and the signal acquisition device are connected in series at both ends of the transformer winding for periodic charging and discharging and oscillation wave signal acquisition; wherein, the obtained oscillation wave signal processing comprises: signal model establishment; band-pass filter pretreatment; Hilbert transform demodulation; effective value (RMS) calculation; Kurtosis calculation; short-time Fourier transform (STFT); autocorrelation function estimation frequency; least squares parameter fitting; phase unwrapping and characteristic parameter fusion to obtain a fault coefficient; result verification and optimization; the fault coefficient is expressed as: ； wherein : comprehensive characteristic parameter, obtained by weighted fusion of effective value (RMS), kurtosis and phase change rate ; a, b, g: weight coefficients According to The value matches the transformer winding fault location.

2. The transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method according to claim 1, wherein: the high-voltage oscillation wave power supply system comprises a high-frequency high-voltage switch and a high-frequency high-voltage DC power supply, and the high-frequency high-voltage switch controls the high-frequency high-voltage DC power supply to periodically charge and discharge the transformer winding.

3. The transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method according to claim 1, wherein: the signal acquisition device comprises a signal amplifier and a data acquisition card, and is used for synchronously recording the oscillation waveforms in the charging and discharging process.

4. The transformer winding deformation and axial displacement fault simulation and oscillation wave signal processing method according to claim 1, wherein: the unfolding arms, the vibration pieces, and the heightening teeth are all three and are evenly distributed in the circumferential direction of the main body structure, realizing multi-position synchronous fault simulation.

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