Transformer winding fault online detection method based on transient overvoltage signal

Abstract

The invention discloses a transformer winding fault online detection method based on transient overvoltage signals. The method comprises the following steps: firstly, building a transformer winding fault detection platform, and acquiring transient overvoltage signals at two ends of each phase winding of a transformer in an active acquisition or passive acquisition mode; obtaining an amplitude-frequency response curve of each phase of the transformer; calculating an accumulative distance matrix DP, an offset relation vector MP, a transverse accumulative offset vector THP and a longitudinal accumulative offset vector TVP; and calculating a transformer winding state evaluation factor: # imgabs0 # evaluates the operation state of each phase of the transformer winding through the winding state evaluation factor. According to the method, the operation state of the transformer winding can be effectively evaluated through simple calculation.

Description

Technical Field

[0001] The present invention belongs to the field of transformer winding state assessment, and in particular relates to an online transformer winding fault detection method based on transient overvoltage signals. Background Art

[0002] Power and distribution transformers are integral components of power supply networks and play a vital role in maintaining the continuity and stability of the electricity supply. Failures in these transformers can lead to power outages and financial losses. Therefore, quickly identifying and repairing faults in power transformer windings is crucial. This not only ensures the transformer can be switched on and off safely but is also essential for improving the reliability and stability of the entire power system.

[0003] When transformer windings are exposed to high-frequency signals, they can be modeled as a complex two-port network consisting of components such as resistors, inductors, and capacitors. In this two-port network model, the magnitude of the inductors and capacitors directly influences the network's behavior. If a winding fault occurs, the parameters of these components, especially the inductors and capacitors, will change significantly, affecting the performance of the entire network. Therefore, by observing changes in the winding's frequency response, we can effectively diagnose and assess whether the winding has a fault. Power systems generate transient overvoltage signals in response to load switching, lightning strikes, external faults, and protective device activation. When the high-frequency component of the transient overvoltage signal is significant, the amplitude-frequency response curve of the transformer winding can be obtained within the 1kHz to 1MHz frequency range. Currently, there is a lack of standards for accurately detecting transformer winding faults using transient overvoltage signals. This patent utilizes the readily available nature of transient overvoltage signals to propose an online transformer winding fault detection method based on transient overvoltage signals. This technology effectively diagnoses transformer winding faults, enabling timely repairs and ensuring stable power system operation, which is crucial for maintaining the continuity and reliability of the entire energy supply. Summary of the Invention

[0004] The present application provides an online detection method for transformer winding faults based on transient overvoltage signals, which can accurately determine the fault type of the transformer according to the proposed characteristic parameters.

[0005] A method for online detection of transformer winding faults based on transient overvoltage signals, characterized in that an experimental platform comprises: a grounding electrode (1), a grounding resistor (2), a transformer high-voltage side neutral point bushing (3), a transformer high-voltage side neutral point voltage sensor (4), a transformer A-phase high-voltage bushing (5a), a transformer B-phase high-voltage bushing (5b), a transformer C-phase high-voltage bushing (5c), a transformer A-phase high-voltage side voltage sensor (6a), a transformer B-phase high-voltage side voltage sensor (6b), a transformer C-phase high-voltage side voltage sensor (6c), a transformer A-phase high-voltage side coupling coil (7a), a transformer B-phase high-voltage side coupling coil (7b), a transformer C phase high voltage side coupling coil (7c), transformer A phase low voltage bushing (8a), transformer B phase low voltage bushing (8b), transformer C phase low voltage bushing (8c), transformer A phase high voltage side lead (9a), transformer B phase high voltage side lead (9b), transformer C phase high voltage side lead (9c), coupling capacitor group (10), A phase high voltage side injection signal switch (11a), B phase high voltage side injection signal switch (11b), C phase high voltage side injection signal switch (11c), high voltage winding (12), low voltage winding (13), computer (14), transformer box (15), transformer core (16), the specific testing method comprises the following steps:

[0006] Step 1: Obtain transient overvoltage signals at the high-voltage side and neutral point of the transformer winding:

[0007] The experimental platform acquires the transient overvoltage signal of the port in two ways: active acquisition and passive acquisition. When in the active acquisition mode, the switch (11a) is first closed, and the computer controls the transient overvoltage signal generating device to generate a standard transient overvoltage signal. The transient overvoltage signal amplitude is 1.5 times the rated voltage of the high-voltage side of the transformer, the peak time is 250us (±20%), and the half-peak time is 2500us (±60%). The transient overvoltage signal is injected into the transformer through the coupling capacitor group (10) and the A-phase high-voltage side coupling coil (7a), and the voltage signal at both ends of the A-phase high-voltage winding of the transformer is acquired through the A-phase high-voltage side voltage sensor (6a) and the high-voltage side neutral point voltage sensor (4). Open the switch (11a), close the switch (11b), repeat the above steps, and obtain the voltage signal at both ends of the transformer B phase high voltage winding through the B phase high voltage side voltage sensor (6b) and the high voltage side neutral point voltage sensor (4), which is recorded as Open the switch (11b), close the switch (11c), repeat the above steps, and obtain the voltage signal at both ends of the transformer C phase high voltage winding through the C phase high voltage side voltage sensor (6c) and the high voltage side neutral point voltage sensor (4), which is recorded as The acquired voltage signal is transmitted to a computer (14) via a high-pass filter and a signal acquisition device;

[0008] When in the passive acquisition mode, switches (11a), (11b), and (11c) are in the disconnected state, and the transient overvoltage signal entering the transformer from the outside is acquired by the high-voltage side neutral point voltage sensor (4), the A-phase high-voltage side voltage sensor (6a), the B-phase high-voltage side voltage sensor (6b), and the C-phase high-voltage side voltage sensor (6c), and is transmitted to the computer (14) through a high-pass filter and a signal acquisition device;

[0009] Step 2: Calculate the amplitude-frequency response curve of the transient overvoltage signal:

[0010] The input voltages of phases A, B, and C are measured respectively ( Where P=A, B, C), output voltage ( Where P = A, B, C) is Fourier transformed to obtain the frequency domain information of the input voltage and output voltage The amplitude-frequency response curve of the three-phase windings A, B, and C is calculated by formula (1):

[0011]

[0012] Where H P (f) is the amplitude-frequency response curve of the P-phase winding, intercepting H P (f) The data with frequency in the range of 1kHz-1MHz is recorded as The data of the amplitude-frequency response curve of the P-phase winding of the transformer when it leaves the factory in the range of 1kHz-1MHz is and A frequency point of the amplitude-frequency response curve is composed of amplitude and frequency, which are recorded as

[0013] Step 3: Calculate the cumulative distance matrix D P :

[0014]

[0015] In the formula, min means taking the minimum value, C P is the distance matrix of the P-phase winding and each value in the matrix is ​​calculated by formula (4);

[0016] Step 4: Obtain the offset relationship vector M of the frequency response curve P :

[0017] The cumulative matrix D for the P-phase winding P To backtrack, first use D P (n,n) is the starting point, and the three points D that are adjacent to the upper left of the current point are found. P (n-1,n),D P (n,n-1),D PThe point with the smallest value in (n-1,n-1) is determined. After determining the position of the minimum point in the cumulative matrix, it is used as the new current point and the above process is repeated until it is backtracked to D P (1,1), the path of the minimum value is the offset relationship vector M of the P-phase winding P :

[0018]

[0019] Where m P k Indicates that each minimum point recorded in the backtracking process is in the cumulative matrix D P The position in α P k , β P k Represents position m P k The row and column indices of

[0020] Step 5: Calculate the lateral cumulative offset vector TH P , longitudinal cumulative offset vector TV P :

[0021]

[0022] Step 6: Calculate the winding condition assessment factor

[0023]

[0024] Where, max(TV P )、min(TV P ) represent the longitudinal cumulative offset vector TV P The maximum and minimum values ​​of ;

[0025] Step 7: Determine the fault status of the transformer winding:

[0026] when When the transformer P phase winding works in normal state, When the transformer P phase winding has an axial displacement fault, When the transformer P phase winding has a short circuit fault or a bulging and warping fault;

[0027] when and When the transformer P phase winding has a short circuit fault, and The P-phase winding of the transformer bulges and warps. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of transformer winding fault detection based on transient overvoltage signals.

[0029] Figure 2 Schematic diagram of transformer winding fault detection platform. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below with reference to the accompanying drawings:

[0031] like Figure 1 As shown in the figure, a transformer winding fault online detection method based on transient overvoltage signal is proposed. The experimental platform is as follows: Figure 2 As shown, the experimental platform includes: grounding electrode (1), grounding resistor (2), transformer high-voltage side neutral point bushing (3), transformer high-voltage side neutral point voltage sensor (4), transformer A phase high-voltage bushing (5a), transformer B phase high-voltage bushing (5b), transformer C phase high-voltage bushing (5c), transformer A phase high-voltage side voltage sensor (6a), transformer B phase high-voltage side voltage sensor (6b), transformer C phase high-voltage side voltage sensor (6c), transformer A phase high-voltage side coupling coil (7a), transformer B phase high-voltage side coupling coil (7b), transformer C phase high-voltage side coupling coil (7c), A transformer A phase low-voltage bushing (8a), a transformer B phase low-voltage bushing (8b), a transformer C phase low-voltage bushing (8c), a transformer A phase high-voltage side lead (9a), a transformer B phase high-voltage side lead (9b), a transformer C phase high-voltage side lead (9c), a coupling capacitor group (10), an A phase high-voltage side injection signal switch (11a), a B phase high-voltage side injection signal switch (11b), a C phase high-voltage side injection signal switch (11c), a high-voltage winding (12), a low-voltage winding (13), a computer (14), a transformer box (15), and a transformer core (16). The specific testing method includes the following steps:

[0032] Step 1: Obtain transient overvoltage signals at the high-voltage side and neutral point of the transformer winding:

[0033] The experimental platform acquires the transient overvoltage signal of the port in two ways: active acquisition and passive acquisition. When in the active acquisition mode, the switch (11a) is first closed, and the computer controls the transient overvoltage signal generating device to generate a standard transient overvoltage signal. The transient overvoltage signal amplitude is 1.5 times the rated voltage of the high-voltage side of the transformer, the peak time is 250us (±20%), and the half-peak time is 2500us (±60%). The transient overvoltage signal is injected into the transformer through the coupling capacitor group (10) and the A-phase high-voltage side coupling coil (7a), and the voltage signal at both ends of the A-phase high-voltage winding of the transformer is acquired through the A-phase high-voltage side voltage sensor (6a) and the high-voltage side neutral point voltage sensor (4). Open the switch (11a), close the switch (11b), repeat the above steps, and obtain the voltage signal at both ends of the transformer B phase high voltage winding through the B phase high voltage side voltage sensor (6b) and the high voltage side neutral point voltage sensor (4), which is recorded as Open the switch (11b), close the switch (11c), repeat the above steps, and obtain the voltage signal at both ends of the transformer C phase high voltage winding through the C phase high voltage side voltage sensor (6c) and the high voltage side neutral point voltage sensor (4), which is recorded as The acquired voltage signal is transmitted to a computer (14) via a high-pass filter and a signal acquisition device;

[0034] When in the passive acquisition mode, switches (11a), (11b), and (11c) are in the disconnected state, and the transient overvoltage signal entering the transformer from the outside is acquired by the high-voltage side neutral point voltage sensor (4), the A-phase high-voltage side voltage sensor (6a), the B-phase high-voltage side voltage sensor (6b), and the C-phase high-voltage side voltage sensor (6c), and is transmitted to the computer (14) through a high-pass filter and a signal acquisition device;

[0035] Step 2: Calculate the amplitude-frequency response curve of the transient overvoltage signal:

[0036] The input voltages of phases A, B, and C are measured respectively ( Where P=A, B, C), output voltage ( Where P = A, B, C) is Fourier transformed to obtain the frequency domain information of the input voltage and output voltage The amplitude-frequency response curve of the three-phase windings A, B, and C is calculated by formula (1):

[0037]

[0038] Where H P (f) is the amplitude-frequency response curve of the P-phase winding, intercepting H P (f) The data with frequency in the range of 1kHz-1MHz is recorded as The data of the amplitude-frequency response curve of the P-phase winding of the transformer when it leaves the factory in the range of 1kHz-1MHz is and A frequency point of the amplitude-frequency response curve is composed of amplitude and frequency, which are recorded as

[0039] Step 3: Calculate the cumulative distance matrix D P :

[0040]

[0041] In the formula, min means taking the minimum value, C Pis the distance matrix of the P-phase winding and each value in the matrix is ​​calculated by formula (4);

[0042] Step 4: Obtain the offset relationship vector M of the frequency response curve P :

[0043] The cumulative matrix D for the P-phase winding P To backtrack, first use D P (n,n) is the starting point, and the three points D that are adjacent to the upper left of the current point are found. P (n-1,n),D P (n,n-1),D P The point with the smallest value in (n-1,n-1) is determined. After determining the position of the minimum point in the cumulative matrix, it is used as the new current point and the above process is repeated until it is backtracked to D P (1,1), the path of the minimum value is the offset relationship vector M of the P-phase winding P :

[0044]

[0045] Where m P k Indicates that each minimum point recorded in the backtracking process is in the cumulative matrix D P The position in α P k , β P k Represents position m P k The row and column indices of

[0046] Step 5: Calculate the lateral cumulative offset vector TH P , longitudinal cumulative offset vector TV P :

[0047]

[0048] Step 6: Calculate the winding condition assessment factor

[0049]

[0050] Where, max(TV P )、min(TV P ) represent the longitudinal cumulative offset vector TV P The maximum and minimum values ​​of ;

[0051] Step 7: Determine the fault status of the transformer winding:

[0052] when When the transformer P phase winding works in normal state, When the transformer P phase winding has an axial displacement fault, When the transformer P phase winding has a short circuit fault or a bulging and warping fault;

[0053] when and When the transformer P phase winding has a short circuit fault, and The P-phase winding of the transformer bulges and warps.

Claims

1. A method for online detection of transformer winding faults based on transient overvoltage signals, characterized in that: The experimental platform includes: grounding electrode (1), grounding resistor (2), transformer high-voltage side neutral point bushing (3), transformer high-voltage side neutral point voltage sensor (4), transformer A phase high-voltage bushing (5a), transformer B phase high-voltage bushing (5b), transformer C phase high-voltage bushing (5c), transformer A phase high-voltage side voltage sensor (6a), transformer B phase high-voltage side voltage sensor (6b), transformer C phase high-voltage side voltage sensor (6c), transformer A phase high-voltage side coupling coil (7a), transformer B phase high-voltage side coupling coil (7b), transformer C phase high-voltage side coupling coil (7c), transformer A transformer A phase low-voltage bushing (8a), a transformer B phase low-voltage bushing (8b), a transformer C phase low-voltage bushing (8c), a transformer A phase high-voltage side lead (9a), a transformer B phase high-voltage side lead (9b), a transformer C phase high-voltage side lead (9c), a coupling capacitor group (10), an A phase high-voltage side injection signal switch (11a), a B phase high-voltage side injection signal switch (11b), a C phase high-voltage side injection signal switch (11c), a high-voltage winding (12), a low-voltage winding (13), a computer (14), a transformer box (15), and a transformer core (16). The specific testing method includes the following steps: Step 1: Obtain transient overvoltage signals at the high-voltage side and neutral point of the transformer winding: The experimental platform acquires the transient overvoltage signal of the port in two ways: active acquisition and passive acquisition. When in the active acquisition mode, the switch (11a) is first closed, and the computer controls the transient overvoltage signal generating device to generate a standard transient overvoltage signal. The transient overvoltage signal amplitude is 1.5 times the rated voltage of the high-voltage side of the transformer, the peak time is 250us (±20%), and the half-peak time is 2500us (±60%). The transient overvoltage signal is injected into the transformer through the coupling capacitor group (10) and the A-phase high-voltage side coupling coil (7a), and the voltage signal at both ends of the A-phase high-voltage winding of the transformer is acquired through the A-phase high-voltage side voltage sensor (6a) and the high-voltage side neutral point voltage sensor (4). Open the switch (11a), close the switch (11b), repeat the above steps, and obtain the voltage signal at both ends of the transformer B phase high voltage winding through the B phase high voltage side voltage sensor (6b) and the high voltage side neutral point voltage sensor (4), which is recorded as Open the switch (11b), close the switch (11c), repeat the above steps, and obtain the voltage signal at both ends of the transformer C phase high voltage winding through the C phase high voltage side voltage sensor (6c) and the high voltage side neutral point voltage sensor (4), which is recorded as The acquired voltage signal is transmitted to a computer (14) via a high-pass filter and a signal acquisition device; When in the passive acquisition mode, switches (11a), (11b), and (11c) are in the disconnected state, and the transient overvoltage signal entering the transformer from the outside is acquired by the high-voltage side neutral point voltage sensor (4), the A-phase high-voltage side voltage sensor (6a), the B-phase high-voltage side voltage sensor (6b), and the C-phase high-voltage side voltage sensor (6c), and is transmitted to the computer (14) through a high-pass filter and a signal acquisition device; Step 2: Calculate the amplitude-frequency response curve of the transient overvoltage signal: The input voltages of phases A, B, and C are Where P=A, B, C), output voltage Where P = A, B, C) is Fourier transformed to obtain the frequency domain information of the input voltage and output voltage The amplitude-frequency response curve of the three-phase windings A, B, and C is calculated by formula (1): Where H P (f) is the amplitude-frequency response curve of the P-phase winding, intercepting H P (f) The data with frequency in the range of 1kHz-1MHz is recorded as The data of the amplitude-frequency response curve of the P-phase winding of the transformer when it leaves the factory in the range of 1kHz-1MHz is and A frequency point of the amplitude-frequency response curve is composed of amplitude and frequency, which are recorded as Step 3: Calculate the cumulative distance matrix D P : In the formula, min means taking the minimum value, C P is the distance matrix of the P-phase winding and each value in the matrix is ​​calculated by formula (4); Step 4: Obtain the offset relationship vector M of the frequency response curve P : The cumulative matrix D for the P-phase winding P To backtrack, first use D P (n,n) is the starting point, and the three points D that are adjacent to the upper left of the current point are found. P (n-1,n),D P (n,n-1),D P The point with the smallest value in (n-1,n-1) is determined. After determining the position of the minimum point in the cumulative matrix, it is used as the new current point and the above process is repeated until it is backtracked to D P (1,1), the path of the minimum value is the offset relationship vector M of the P-phase winding P : Where m P k Indicates that each minimum point recorded in the backtracking process is in the cumulative matrix D P The position in α P k , β P k Represents position m P k The row and column indices of Step 5: Calculate the lateral cumulative offset vector TH P , longitudinal cumulative offset vector TV P : Step 6. Calculate the winding condition assessment factor FT1 P 、 Where, max(TV P )、min(TV P ) represent the longitudinal cumulative offset vector TV P The maximum and minimum values ​​of ; Step 7: Determine the fault status of the transformer winding: When FT1 P ≤0.4, the transformer P-phase winding works in normal state. When 0.4<FT1 P ≤1.0, the transformer P-phase winding has an axial displacement fault. When FT1 P When >1.0, the transformer P-phase winding has a short circuit fault or a bulging and warping fault; When FT1 P >1.0 and When the transformer P phase winding has a short circuit fault, when FT1 P >1.0 and The P-phase winding of the transformer bulges and warps.

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