Transformer mechanical instability active protection method, device, equipment and storage medium

Abstract

The present invention discloses a method, device, equipment and storage medium for active protection of mechanical instability of transformers. The method for active protection of mechanical instability of transformers of the present invention comprises: real-time acquisition of voltage, current, oil pressure, oil temperature and vibration signals of the oil tank surface of the transformer; when the current amplitude of the transformer is greater than or equal to 1.5 times the current rating or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0 seconds before the abnormal trigger of the transformer and within 0.3-0.4 seconds after the trigger are used to evaluate the mechanical state of the transformer winding, and at the same time, the winding ratio change rate, odd harmonic ratio and sound-current ratio within 0.2-1.0 seconds before the trigger and within 0.3-0.4 seconds after the trigger are calculated, and the active protection strategy for mechanical instability of the transformer is given. The present invention can integrate electrical parameters and non-electrical operating state parameters to instantly evaluate the mechanical strength of the transformer winding, and timely give an active protection strategy for mechanical instability of the transformer, so as to realize comprehensive perception and active protection of the mechanical state of the transformer operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transformers, and relates to a method, a device, a equipment and a storage medium for active protection of transformer mechanical instability. Background Art

[0002] Power transformers, especially large oil-immersed transformers of 110kV and above, are key core equipment of the power grid, and their health status is directly related to the safe and stable operation of the power system. With the increasing system capacity, equipment and line numbers, the short-circuit impact current and frequency of transformers have increased accordingly. The short-circuit impact of reclosing has caused great damage to the mechanical stability of the transformer, seriously affecting the safe and stable operation of the equipment. However, due to technical difficulties such as the complex development mechanism of mechanical defects, the inability to directly perceive the internal mechanical state, and the decentralized health status parameters, there is a lack of effective online real-time perception and early warning means, and it is impossible to timely and effectively warn of mechanical instability defects when the equipment is in operation, which may cause the equipment to operate with defects for a long time, and in severe cases, it may cause equipment failure and shutdown, resulting in huge economic losses.

[0003] At present, the commonly used transformer mechanical instability diagnosis methods are all power outage test methods: frequency response method, low voltage short-circuit impedance test method and winding dielectric loss capacitance test method, which have disadvantages such as intervention, difficulty in obtaining state quantities, long test intervals, and large workload. The existing online frequency response method and online monitoring devices for mechanical instability based on vibration signals have disadvantages such as low sensitivity, unclear thresholds, and a certain probability of missed judgment, which cannot meet the actual production needs.

[0004] Therefore, it is urgent to develop an active transformer protection and online monitoring device to accurately evaluate the mechanical state of the transformer, promptly provide an active protection strategy for transformer mechanical defects, achieve accurate diagnosis and scientific decision-making of transformer defect faults, improve the operation and maintenance level of power equipment, and ensure the safe and stable operation of the power grid. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide a method, device, equipment and storage medium for active protection of transformer mechanical instability with multi-source parameter fusion, which can integrate electrical parameters and non-electrical operating status parameters to instantaneously evaluate the mechanical strength of the transformer winding, and timely provide an active protection strategy for transformer mechanical instability, so as to realize comprehensive perception and active protection of the mechanical state of the transformer operation.

[0006] In a first aspect, the present invention provides a transformer mechanical instability active protection method, which comprises:

[0007] Real-time collection of the voltage, current, oil pressure, oil temperature and oil tank surface vibration signal of the transformer, wherein the oil tank surface vibration signal is processed to obtain a vibration waveform;

[0008] When the transformer current amplitude is greater than or equal to 1.5 times the rated current or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0 seconds before the transformer abnormal trigger and within 0.3-0.4 seconds after the trigger are used to evaluate the transformer winding mechanical state, and the winding ratio change rate, odd harmonic ratio and sound-to-current ratio within 0.2-1.0 seconds before the trigger and within 0.3-0.4 seconds after the trigger are calculated;

[0009] When any of the following conditions is met: the odd harmonic ratio is greater than or equal to 0.3, the winding ratio change rate is greater than or equal to 0.01, and the acoustic-current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and communication is carried out with the line protection of the outgoing line interval connected to the transformer to obtain the protection tripping signal of each line protection, and a locking reclosing signal is sent to the tripped line protection accordingly.

[0010] Furthermore, when all the conditions of the odd harmonic ratio being less than 0.3, the winding ratio change rate being less than 0.01, and the acoustic-current ratio being less than 4.5 are met, the internal windings of the transformer are not deformed, and the reclosing function of the line protection device operates normally.

[0011] Furthermore, when the transformer current amplitude is less than 1.5 times the rated current and the vibration amplitude is less than 1.5 times the full-load vibration amplitude, the vibration characteristic quantity is extracted and the winding ratio change rate is calculated at the same time. The transformer vibration characteristic quantity, winding ratio change rate, oil temperature and oil pressure data are uploaded at a regular period to evaluate the mechanical state of the transformer winding.

[0012] Furthermore, the vibration characteristic quantities include frequency complexity, certainty, energy difference rate, vibration correlation level, odd harmonic ratio, effective energy ratio, vibration acceleration peak-to-peak value and sound-to-flow ratio.

[0013] In a second aspect, the present invention provides a transformer mechanical instability active protection device, which includes a signal acquisition module, a data processing module, a low-frequency recording module, a trigger module, a high-frequency recording module and an active protection module;

[0014] The signal acquisition module amplifies and filters the voltage, current, oil pressure, oil temperature and vibration signals of the oil tank surface. The vibration waveform is obtained by processing the vibration signal of the oil tank surface and then transmitted to the data processing module.

[0015] The data processing module extracts the vibration characteristic quantity, calculates the winding ratio change rate, and uploads it to the low-frequency recording module at a fixed period; the low-frequency recording module uploads the winding ratio change rate, vibration characteristic quantity, oil temperature and oil pressure to the health management and control platform according to the prescribed protocol to evaluate the mechanical state of the transformer winding;

[0016] When the transformer current amplitude is greater than or equal to 1.5 times the rated value or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the trigger module is activated, and the data processing module synchronously uploads the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0s before the abnormal trigger and within 0.3-0.4s after the abnormal trigger to the high-frequency recording module and the active protection module; the high-frequency recording module uploads the data to the health management and control platform according to the prescribed protocol to evaluate the mechanical state of the transformer winding; the active protection module calculates the winding ratio change rate, odd harmonic ratio and sound-to-current ratio within 0.2-1.0s before the abnormal trigger and within 0.3-0.4s after the abnormal trigger;

[0017] When any of the following conditions is met: the odd harmonic ratio is greater than or equal to 0.3, the winding ratio change rate is greater than or equal to 0.01, and the acoustic-current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and communication is carried out with the line protection of the outgoing line interval connected to the transformer to obtain the protection tripping signal of each line protection, and a locking reclosing signal is sent to the tripped line protection accordingly.

[0018] In a third aspect, the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method when executing the computer program.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the described method when executed by a processor.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1) The present invention explores the intrinsic connection between transformer winding deformation and vibration-electrical signals, integrates electrical parameters and non-electrical operating status parameters to instantaneously evaluate the mechanical strength of transformer windings, makes up for the shortcomings of a single monitoring method, improves the online detection rate and monitoring efficiency of transformer winding deformation under operating conditions, optimizes the transformer reclosing short-circuit active protection strategy, and realizes comprehensive perception and active protection of the transformer's operating mechanical state, thereby further improving the intrinsic safety of oil-immersed power transformers.

[0022] 2) The present invention uses the odd harmonic ratio of winding vibration, the winding ratio change rate and the acoustic-current ratio as key parameters and threshold settings, which can accurately reflect the winding mechanical state inside the transformer after being subjected to a short-circuit impact.

[0023] 3) Compared with the short-circuit impedance method, the transformation ratio change rate obtained by inverting the real-time voltage and current of the transformer in the present invention can more sensitively reflect the mechanical state of the winding, and can be used as an online monitoring state quantity for early warning protection.

[0024] 4) Periodically upload transformer voltage, current amplitude, frequency complexity, certainty, energy difference rate, vibration correlation level, odd harmonic ratio, effective energy ratio, vibration acceleration peak-to-peak value, acoustic-to-current ratio, operating voltage peak-to-peak value, current peak-to-peak value, winding ratio, oil pressure, and oil temperature to the health management and control platform, which can evaluate the mechanical status of the winding online and guide actual operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a flow chart of the transformer mechanical instability active protection method of the present invention;

[0027] Figure 2 A schematic diagram of a transformer mechanical instability active protection device according to the present invention;

[0028] Figure 3 A comparison diagram of the ratio change rate of each group of short-circuit tests in the application example of the present invention;

[0029] Figure 4 This is a graph showing the proportion of vibration frequency components in a phase A short-circuit test in an application example of the present invention (upper sensor);

[0030] Figure 5 This is a diagram showing the proportion of vibration frequency components in a B-phase short-circuit test in an application example of the present invention (upper sensor);

[0031] Figure 6 This is a graph showing the proportion of vibration frequency components in a C-phase short-circuit test in an application example of the present invention (upper sensor);

[0032] Figure 7 It is a relationship diagram between the high-to-center short-circuit current and the time-domain peak value of the sound pressure in the application example of the present invention;

[0033] Figure 8 A schematic diagram of a logical structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment is a transformer mechanical instability active protection method. Figure 1 As shown, the steps are as follows:

[0037] Real-time collection of the voltage, current, oil pressure, oil temperature and oil tank surface vibration signal of the transformer, wherein the oil tank surface vibration signal is processed to obtain a vibration waveform;

[0038] When the transformer current amplitude is greater than or equal to 1.5 times the rated current or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1 seconds before the transformer abnormal trigger and within 0.3-0.4 seconds after the trigger are used to evaluate the transformer winding mechanical state, and the winding ratio change rate, odd harmonic ratio and sound-to-current ratio within 0.2-1 seconds before the trigger and within 0.3-0.4 seconds after the trigger are calculated;

[0039] When any of the following conditions is met: odd harmonic ratio is greater than or equal to 0.3, winding ratio change rate is greater than or equal to 0.01, and acoustic current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and communication is carried out with the line protection of the outgoing line interval connected to the transformer to obtain the protection tripping signal of each line protection, and a locking reclosing signal is sent to the tripped line protection accordingly; when the line protection does not trip, an alarm message of transformer winding deformation is sent; when all the conditions of odd harmonic ratio is less than 0.3, winding ratio change rate is less than 0.01, and acoustic current ratio is less than 4.5 are met, the internal winding of the transformer is not deformed, and the reclosing function of the line protection device operates normally;

[0040] When the transformer current amplitude is less than 1.5 times the rated current and the vibration amplitude is less than 1.5 times the full-load vibration amplitude, the vibration characteristic quantity is extracted and the winding ratio change rate is calculated. The transformer vibration characteristic quantity, winding ratio change rate, oil temperature and oil pressure data are uploaded in a 5-minute cycle to evaluate the mechanical state of the transformer winding, so that the operation and maintenance personnel can grasp the mechanical state of the transformer in time and guide the timely maintenance of the transformer.

[0041] Specifically, the winding ratio change rate The calculation process is as follows:

[0042] The calculation formula of winding ratio is as follows:

[0043] ,

[0044] In the formula, and are the effective values ​​of the high-voltage side current and the low-voltage side current of the transformer respectively.

[0045] If the relative change rate of the transformer ratio before and after the abnormal trigger exceeds 0.01, it is considered that the winding ratio has changed, as shown in the following formula:

[0046] ,

[0047] In the formula, is the winding ratio change rate, and The winding ratios are calculated 0.2-1s before the abnormal triggering moment and 0.3-0.4s after the abnormal triggering moment.

[0048] Specifically, the calculation process of odd harmonic ratio OHR is as follows:

[0049] Odd harmonic ratio: characterizes the mechanical state of the transformer during short-circuit impact; due to the existence of electromechanical coupling, when the winding mode changes, a harmonic signal with an odd multiple of 50Hz will appear in the transient acoustic vibration signal. Therefore, 50Hz, 150Hz, 250Hz, ..., 950Hz, a total of 10 frequencies are defined as odd harmonics, and the odd harmonic ratio OHR is:

[0050] ,

[0051] In the formula, A 2i+1 is the 50Hz odd harmonic energy, A j It is 50Hz energy.

[0052] Specifically, the calculation process of the acoustic flow ratio PI is as follows:

[0053] Acoustic-current ratio PI: The ratio of sound pressure intensity to current under different currents, used to characterize the vibration intensity under different currents.

[0054] ,

[0055] In the formula, V maxa is the average value of the maximum sound pressure amplitude in 1 second of data, I maxa is the maximum current average value in 1 second data, I n is the rated current of the transformer.

[0056] Specifically, the vibration characteristic quantities are frequency complexity FCD, determinism DET, energy difference rate EDR, vibration correlation level VCL, odd harmonic ratio OHR, effective energy ratio EER, vibration acceleration peak-to-peak value PPV and acoustic flow ratio PI.

[0057] Frequency complexity FCD: It characterizes the dispersion degree of vibration energy in the frequency domain. When the transformer winding is deformed, mechanical instability will cause the vibration energy to be dispersed in more frequency components, and the FCD value will increase significantly.

[0058] ,

[0059] In the formula, p f Indicates frequency f The harmonic proportion under.

[0060] Deterministic DET: Characterizes the stability of the vibration signal in terms of periodicity, and its value is between 0 and 1. When the transformer winding is deformed, mechanical instability will increase the uncertainty of the system and generate random vibration, resulting in a decrease in the DET value.

[0061] ,

[0062] In the formula, l is the length of the diagonal line; P(l) The length is l The number of diagonals; l min is the minimum length of the diagonal line, usually l min =2, m=n-(DE-1)T, DE is the embedding dimension, and T is the delay coefficient.

[0063] Energy difference rate (EDR): It characterizes the overall change relationship of vibration energy at each measuring point over time, and its value is between 0 and 1. A normal transformer maintains mechanical stability during operation, and its energy in each frequency band does not change much, and the EDR is usually small. When the transformer winding deforms, the EDR value will suddenly increase.

[0064] ,

[0065] In the formula, v i For the i eigenvectors; μ is the average energy of the eigenvectors; N is the number of vibration sensors.

[0066] Vibration correlation level VCL: It characterizes the correlation degree of vibration between each measuring point, and its value is between 0 and 1. For a normal transformer, the change mode of vibration signals at each measuring point is highly similar, and the VCL value is close to 1. When the transformer has winding deformation and mechanical instability, the vibration characteristics of each measuring point change, the consistency is weakened, and the VCL value decreases accordingly.

[0067] ,

[0068] In the formula, is the eigenvalue of the vibration characteristic matrix.

[0069] Effective Energy Ratio (EER): refers to the ratio of the integral multiple system frequency energy to the total vibration energy, which is used to reflect the degree to which the vibration of the transformer tank surface is affected by external interference (such as cooling system vibration, grid harmonics, etc.). When the transformer is seriously affected by external interference, the EER will decrease. The frequency range involved in calculating the EER is related to the instrument sampling frequency, and the formula is as follows:

[0070]

[0071] In the formula, X ( f ) indicates the frequency is f Vibrational energy; Indicates rounding down; f s is the sampling frequency; σ is the threshold for energy inclusion, which is usually ; f sys is the system frequency 50Hz, and h is the harmonic multiple.

[0072] Vibration acceleration peak-to-peak value PPV: characterizes the surface vibration intensity of the transformer, and measures 1 second of vibration data every 5 minutes;

[0073] PPV = V max - V minv ,

[0074] In the formula, V max is the maximum vibration amplitude in 1 second of data, V min It is the minimum vibration amplitude in 1 second data.

[0075] Example 2

[0076] This embodiment is a transformer mechanical instability active protection device. Figure 2 As shown, it consists of a signal acquisition module, a data processing module, a low-frequency recording module, a trigger module, a high-frequency recording module and an active protection module.

[0077] The signal acquisition module amplifies and filters the voltage, current, oil pressure, oil temperature and vibration signals of the oil tank surface. The vibration waveform is obtained by processing the vibration signal of the oil tank surface and then transmitted to the data processing module.

[0078] The data processing module extracts the vibration characteristic quantity, calculates the winding ratio change rate, and uploads it to the low-frequency recording module at a fixed period; the low-frequency recording module uploads the winding ratio change rate, vibration characteristic quantity, oil temperature and oil pressure to the health management and control platform according to the prescribed protocol to evaluate the mechanical state of the transformer winding.

[0079] When the transformer current amplitude is greater than or equal to 1.5 times the current rating or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the trigger module is activated, and the data processing module synchronously uploads the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0s before the abnormal trigger and within 0.3-0.4s after the abnormal trigger to the high-frequency recording module and the active protection module; the high-frequency recording module uploads the data to the health management and control platform in accordance with the prescribed protocol to evaluate the mechanical state of the transformer winding; the active protection module calculates the winding ratio change rate, odd harmonic ratio and acoustic-current ratio within 0.2-1.0s before the abnormal trigger and within 0.3-0.4s after the abnormal trigger. The calculation formula is detailed in Example 1.

[0080] When any one of the following conditions is met: the odd harmonic ratio is greater than or equal to 0.3, the winding ratio change rate is greater than or equal to 0.01, and the acoustic-current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and communication is carried out with the line protection of the outgoing line interval connected to the transformer to obtain the protection tripping signal of each line protection, and a locking reclosing signal is sent to the tripped line protection accordingly; when the line protection does not trip, an alarm information about the transformer winding deformation is sent; when all the conditions are met: the odd harmonic ratio is less than 0.3, the winding ratio change rate is less than 0.01, and the acoustic-current ratio is less than 4.5, the internal winding of the transformer is not deformed, and the reclosing function of the line protection device operates normally.

[0081] When the transformer current amplitude is less than 1.5 times the rated value and the vibration amplitude is less than 1.5 times the full-load vibration amplitude, the vibration characteristic quantity is extracted and the winding ratio change rate is calculated. The transformer vibration characteristic quantity, winding ratio change rate, oil temperature and oil pressure data are uploaded to the health management and control platform in a 5-minute cycle to evaluate the mechanical state of the transformer winding online.

[0082] Specifically, the vibration characteristic quantities include frequency complexity, certainty, energy difference rate, vibration correlation level, odd harmonic ratio, effective energy ratio, vibration acceleration peak-to-peak value and sound-to-flow ratio. The calculation formula is detailed in Example 1.

[0083] This embodiment uses a microsystem built with a SIP chip to integrate and sense multiple source data such as the electrical state quantity and non-electrical operation state quantity of the transformer, where the electrical state quantity is the operating voltage and current, and the non-electrical operation state quantity is the vibration, oil pressure, and oil temperature of the transformer oil tank surface. The vibration signal is collected in real time by an acceleration sensor installed on the surface of the oil tank corresponding to the transformer winding, where the sampling rate of the vibration sensor is greater than 20kHz; the voltage and current signals rely on the secondary fault recording device to realize the real-time collection of operating current and voltage data through a hard node method, and the voltage and current sampling rate is greater than 4kHz; the oil temperature and oil pressure are monitored in real time by a built-in optical fiber sensor, and the signal sampling rate is greater than 1kHz.

[0084] This embodiment realizes the online acquisition of transformer vibration and electrical signals through lossless sensing, extracts the characteristic quantities mainly related to the mechanical instability of the transformer, optimizes the transformer reclosing short-circuit fault protection strategy, and realizes the primary and secondary fusion active protection technology of transformer mechanical instability defect warning, effectively solving the problems of transformer mechanical stability evaluation, monitoring and early warning, and active protection under the impact of reclosing short-circuit actually faced in production operation.

[0085] Application Examples

[0086] The device described in Example 2 was used for the following applications.

[0087] From December 1 to 4, 2023, a sudden short circuit and short circuit reclosing test was carried out. The characteristic quantities such as winding ratio change rate, odd harmonic ratio, and acoustic current ratio proposed in the present invention can accurately reflect the state of the transformer winding, and are confirmed in the routine test and disassembly after the test. The main parameters of the tested transformer are shown in Table 1.

[0088] Table 1 Main parameters of the tested transformer

[0089]

[0090] 1. Experimental Project

[0091] (1) Medium to low short circuit impact test

[0092] During the test, phase A is tapped at 1, phase B is tapped at 9b, and phase C is tapped at 17. During the test, the acoustic vibration is monitored, the reactance and swept frequency impedance are measured before and after a single short-circuit impact, and the winding frequency response and oil color spectrum are measured before and after the medium to low short-circuit impact test.

[0093] (2) High-to-center short-circuit impact test

[0094] During the test, phase A is tapped at 1, phase B is tapped at rated 9b, and phase C is tapped at 17. During the test, the acoustic vibration is monitored, the reactance and swept frequency impedance are measured after a single short-circuit impact, and the winding frequency response is measured after a high-to-center short-circuit impact test.

[0095] (3) Reclosing test

[0096] During the test, phase A was tapped at 17, phase B was tapped at 9b, and phase C was tapped at 1. The main test parameters are shown in Table 2. During the test, the acoustic vibration was monitored, the reactance and swept frequency impedance were measured after a single test, and routine tests such as winding frequency response, DC resistance, and oil chromatography were carried out after the reclosing test.

[0097] Table 2 Reclosing test parameters

[0098]

[0099] 2. Feature quantity calculation

[0100] When the current amplitude is greater than 1.5 times the rated current of the transformer or the vibration amplitude is greater than 1.5 times the full-load vibration amplitude, the calculation results of the winding ratio change rate, odd harmonic ratio and sound-to-current ratio characteristic quantities are as follows:

[0101] (1) Winding ratio change rate

[0102] By calculating the real-time ratio change , it is possible to judge the short circuit between turns. If the relative change rate of the transformer ratio before and after the abnormal trigger exceeds 0.01, it is considered that the winding ratio has changed, as shown in the following formula:

[0103] ,

[0104] In the formula, is the winding ratio change rate, and The winding ratios are calculated 0.1s before and 0.02s after the abnormal triggering moment respectively.

[0105] After calculation, the ratio change rate of each group of short-circuit test is Figure 3 As shown in the figure, in the third short-circuit impact of the high-voltage pair of phase A and each reclosing test, the change in the high-voltage pair ratio is between 0.05 and 0.07, and the ratio becomes smaller, which can be judged as a turn-to-turn short circuit on the medium-voltage side of phase A.

[0106] (2) Odd harmonic ratio

[0107] The frequency components during transformer short circuit can generally be divided into 50Hz, 150Hz, 100Hz, half-frequency ratio (the total proportion of 25Hz, 75Hz, 125Hz, etc.) and other components. By analyzing the changes in frequency components, the mechanical state inside the transformer can be judged. The transformer odd harmonic ratio is the sum of 50Hz and 150Hz.

[0108] The 50Hz component of the three short-circuit impulses in the A-phase high-to-middle short-circuit test and the B-phase middle-to-low short-circuit test gradually increased, and the 50Hz component of the four short-circuit impulses in the A-phase reclosing test gradually decreased. Among them, the spectral component of the third short-circuit in the A-phase high-to-middle short-circuit changed significantly, and the odd harmonic ratio was 0.46, which was greater than the threshold of 0.3. Figure 4-Figure 6 .

[0109] (3) Acoustic flow ratio

[0110] The square of the current is related to the winding vibration or the current amplitude. Figure 7 This is the relationship between the square of the short-circuit current and the sound pressure. At rated current, the PI value of phase A is greater than the PI value of the BC two-phase windings, and is greater than 4.5, and the A phase winding has winding deformation.

[0111] 3. Post-test inspection

[0112] On December 5-6, after the reclosing test, routine tests such as transformation ratio test, no-load current test, and dissolved gas detection in oil were carried out.

[0113] (1) Transformation ratio test

[0114] The maximum deviation of the high-pressure-low-pressure ratio CA / ca is 7.91%, the maximum deviation of the ratio AB / ab is 2.82%, and the high-pressure-medium-pressure ratio AB / A m B m The maximum deviation is 6.33%, the ratio CA / C m A m The maximum deviation is 4.81%, and the ratio deviation is large, exceeding the standard requirement of 0.5%. The ratio deviation related to the A-phase winding is large, and the analysis shows that the possibility of abnormality at the A-phase high-voltage and medium-voltage windings is high.

[0115] (2) No-load current measurement

[0116] In the no-load current measurement, the three-phase low-voltage side currents were 34.198A, 0.351A, and 34.156A, respectively, exceeding the standard requirements (the standard requires no more than 0.2A).

[0117] (3) Oil chromatography detection

[0118] The oil chromatography data are shown in Table 3. The dissolved acetylene in the oil was 2.77 μL / L 24 hours after the test, and the maximum dissolved acetylene in the oil was 6.46 μL / L 48 hours after the test, which did not meet the standard requirements (the standard requires that acetylene should not be present in the oil).

[0119] Table 3 Offline oil chromatography data

[0120]

[0121] (4) Inspection of hanging cover

[0122] On December 8, after the transformer was returned to the factory, a cover inspection was carried out and it was found that the A-phase coil was offset toward the side yoke, which was more obvious at the upper end. The end ring at the upper end was damaged, and the pressure block and gasket were detached and deformed.

[0123] (5) Disassembly inspection

[0124] On December 11, the upper clamp was disassembled. On December 12, the iron yoke was removed. On December 13, the coils were pulled out in groups.

[0125] When pulling out the iron yoke, the first row of oil channel buckles on the iron core near the upper end of the A-phase coil and near the side yoke fell off; the step wood was damaged; the upper laminate at the bottom of the A-phase iron yoke was broken in two sections, one on each side near the side yoke window, and separation occurred between the layers of the laminate.

[0126] Below the upper pressure plate, the insulating ring was severely damaged, and large areas of corner ring fragments, electrostatic ring frames, insulating paper, and insulating wire fragments were found. The wires were scattered and severely deformed.

[0127] There is a big hole in the medium voltage outer screen, which is caused by the horn pad used for transposition. In the medium voltage winding of phase A, the middle of the coil begins to bulge upward near the side yoke. The top 6 coils (height 40-60cm) are arched upward, 6-7 coils are turned outward and loose, and the insulation paper of the paper-wrapped insulation is damaged. 15-16 coils (height 28cm) are arched, and the insulation of 42-43 coils is damaged. The bottom end is arched about 20-30mm. The normal coil height is about 175cm, the height of the deformed part is 184cm, and the length in the circumferential direction is about 108cm.

[0128] No obvious abnormalities were found in phases B and C.

[0129] (6) Analysis of disintegration

[0130] Based on the comprehensive test and disassembly inspection, it is analyzed that the short-circuit resistance of the A-phase medium-voltage winding is insufficient and abnormalities occur under high-medium short-circuit conditions. The damage is aggravated by the short-term (1s interval) continuous short-circuit and large current in the high-medium reclosing test (the A-phase test was at 17 taps, the current was 50%-70%, the worst working condition), resulting in axial deformation of the A-phase medium-voltage winding, upward arching and loose strands of the coil, and inter-turn or inter-cake discharge after the external insulation of the coil is damaged, and intermittent short circuits between turns or between cakes of the winding occur, resulting in abnormal transformation ratio, no-load current, and oil dissolved gas analysis data.

[0131] The characteristic parameters winding ratio change rate, odd harmonic ratio and acoustic-to-current ratio proposed in the present invention can accurately reflect the state of transformer windings.

[0132] Example 3

[0133] This embodiment provides an electronic device, comprising: at least one processor; and a memory connected to the at least one processor in communication. The memory stores a computer program executable by the at least one processor, and when the computer program is executed by the at least one processor, the electronic device executes the method according to Embodiment 1 of the present invention.

[0134] Example 4

[0135] This embodiment provides a non-transitory computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor of a computer, is used to cause the computer to execute the method according to Embodiment 1 of the present invention.

[0136] refer to Figure 8 , a block diagram of an electronic device 400 that can be used as a server or client of the present invention will now be described, which is an example of a hardware device that can be applied to various aspects of the present invention. The electronic device is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0137] like Figure 8 As shown, the electronic device 400 includes a computing unit 401, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 402 or a computer program loaded from a storage unit 408 into a random access memory (RAM) 403. In the RAM 403, various programs and data required for the operation of the electronic device 400 can also be stored. The computing unit 401, the ROM 402, and the RAM 403 are connected to each other via a bus 404. An input / output (I / O) interface 405 is also connected to the bus 404.

[0138] A plurality of components in the electronic device 400 are connected to the I / O interface 405, including: an input unit 406, an output unit 407, a storage unit 408, and a communication unit 409. The input unit 406 may be any type of device capable of inputting information to the electronic device 400, and the input unit 406 may receive input digital or character information, and generate key signal inputs related to user settings and / or function control of the electronic device. The output unit 407 may be any type of device capable of presenting information, and may include, but is not limited to, a display, a speaker, a video / audio output terminal, a vibrator, and / or a printer. The storage unit 408 may include, but is not limited to, a disk, an optical disk. The communication unit 409 allows the electronic device 400 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks, and may include, but is not limited to, a modem, a network card, an infrared communication device, a wireless communication transceiver, and / or a chipset, such as a Bluetooth™ device, a WiFi device, a WiMax device, a cellular communication device, and / or the like.

[0139] The computing unit 401 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 401 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 401 performs the various methods and processes described above. For example, in some embodiments, the aforementioned metal corrosion prediction method may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 408. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 400 via the ROM 402 and / or the communication unit 409. In some embodiments, the computing unit 401 may be configured to perform the aforementioned metal corrosion prediction method in any other appropriate manner (e.g., by means of firmware).

[0140] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0141] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0142] As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, apparatus, and / or device (e.g., disk, optical disk, memory, programmable logic device (PLD)) for providing machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal for providing machine instructions and / or data to a programmable processor.

[0143] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0144] The systems and techniques described herein may be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), and the Internet.

[0145] A computer system may include clients and servers. Clients and servers are generally remote from each other and usually interact through a communication network. The relationship of client and server is generated by computer programs running on respective computers and having a client-server relationship to each other.

[0146] It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the scope of protection of the present invention.

Claims

1. A transformer mechanical instability active protection method, characterized in that: include: Real-time collection of the voltage, current, oil pressure, oil temperature and oil tank surface vibration signal of the transformer, wherein the oil tank surface vibration signal is processed to obtain a vibration waveform; When the transformer current amplitude is greater than or equal to 1.5 times the rated current or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0 seconds before the transformer abnormal trigger and within 0.3-0.4 seconds after the trigger are used to evaluate the transformer winding mechanical state, and the winding ratio change rate, odd harmonic ratio and sound-to-current ratio within 0.2-1.0 seconds before the trigger and within 0.3-0.4 seconds after the trigger are calculated; When any of the following conditions is met: odd harmonic ratio is greater than or equal to 0.3, winding ratio change rate is greater than or equal to 0.01, and acoustic current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and the line protection of the outgoing line bay connected to the transformer is communicated with to obtain the protection tripping signal of each line protection, and accordingly a blocking reclosing signal is sent to the tripped line protection; The odd harmonic ratio is used to characterize the mechanical state of the transformer during short-circuit impact; the odd harmonic ratio OHR is: ， In the formula, A 2i+1 is the 50Hz odd harmonic energy, A j It is 50Hz energy; Acoustic-to-current ratio PI: The ratio of sound pressure intensity to current under different currents. It is used to characterize the vibration intensity under different currents. The calculation process of the acoustic-to-current ratio PI is as follows: ， In the formula, V maxa is the average value of the maximum sound pressure amplitude in 1 second of data, I maxa is the maximum current average value in 1 second data, I n is the rated current of the transformer.

2. The transformer mechanical instability active protection method according to claim 1 is characterized in that: When all the conditions of odd harmonic ratio less than 0.3, winding ratio change rate less than 0.01, and acoustic-current ratio less than 4.5 are met, the internal winding of the transformer is not deformed and the reclosing function of the line protection device operates normally.

3. The transformer mechanical instability active protection method according to claim 1 or 2, characterized in that: When the transformer current amplitude is less than 1.5 times the rated current and the vibration amplitude is less than 1.5 times the full-load vibration amplitude, the vibration characteristic quantity is extracted and the winding ratio change rate is calculated. The transformer vibration characteristic quantity, winding ratio change rate, oil temperature and oil pressure data are uploaded at a regular period to evaluate the mechanical state of the transformer winding.

4. The transformer mechanical instability active protection method according to claim 3 is characterized in that: The vibration characteristic quantities include frequency complexity, certainty, energy difference rate, vibration correlation level, odd harmonic ratio, effective energy ratio, vibration acceleration peak-to-peak value and sound-to-flow ratio; Frequency complexity FCD: characterizes the dispersion of vibration energy in the frequency domain; When the transformer windings are deformed, mechanical instability will cause the vibration energy to be dispersed over more frequency components, and the FCD value will increase significantly. Deterministic DET: Characterizes the stability of the vibration signal in terms of periodicity, and its value is between 0 and 1. When the transformer winding is deformed, mechanical instability will increase the uncertainty of the system and generate random vibration, resulting in a decrease in the DET value. Energy difference rate (EDR): It characterizes the overall change relationship of vibration energy at each measuring point over time, and its value is between 0 and 1. When the transformer winding is deformed, the EDR value will suddenly increase. Vibration correlation level VCL: It characterizes the correlation degree of vibration between each measuring point, and its value is between 0 and 1. For a normal transformer, the change mode of vibration signals at each measuring point is highly similar, and the VCL value is close to 1. When the transformer has winding deformation and mechanical instability, the vibration characteristics of each measuring point change, the consistency is weakened, and the VCL value decreases accordingly. Effective Energy Ratio (EER): refers to the ratio of the integral multiple system frequency energy to the total vibration energy, which is used to reflect the degree of external interference on the transformer tank surface vibration. When the transformer is seriously interfered by external interference, the EER will decrease. Vibration acceleration peak-to-peak value PPV: Characterizes the surface vibration intensity of the transformer, and measures 1 second vibration data every 5 minutes.

5. A transformer mechanical instability active protection device, characterized in that: It includes signal acquisition module, data processing module, low-frequency recording module, trigger module, high-frequency recording module and active protection module; The signal acquisition module amplifies and filters the voltage, current, oil pressure, oil temperature and vibration signals of the oil tank surface. The vibration waveform is obtained by processing the vibration signal of the oil tank surface and then transmitted to the data processing module. The data processing module extracts the vibration characteristic quantity, calculates the winding ratio change rate, and uploads it to the low-frequency recording module at a fixed period; the low-frequency recording module uploads the winding ratio change rate, vibration characteristic quantity, oil temperature and oil pressure to the health management and control platform according to the prescribed protocol to evaluate the mechanical state of the transformer winding; When the transformer current amplitude is greater than or equal to 1.5 times the current rating or the vibration amplitude is greater than or equal to 1.5 times the full-load vibration amplitude, the trigger module is activated, and the data processing module synchronously uploads the voltage, current, vibration waveform, oil pressure and oil temperature data within 0.2-1.0 seconds before the abnormal trigger and within 0.3-0.4 seconds after the abnormal trigger to the high-frequency recording module and the active protection module; the high-frequency recording module uploads the data to the health management and control platform according to the prescribed protocol to evaluate the mechanical state of the transformer winding; the active protection module calculates the winding ratio change rate, odd harmonic ratio and sound-to-current ratio within 0.2-1.0 seconds before the abnormal trigger and within 0.3-0.4 seconds after the abnormal trigger; When any of the following conditions is met: odd harmonic ratio is greater than or equal to 0.3, winding ratio change rate is greater than or equal to 0.01, and acoustic current ratio is greater than or equal to 4.5, it is determined that there is obvious winding deformation inside the transformer, and the line protection of the outgoing line bay connected to the transformer is communicated with to obtain the protection tripping signal of each line protection, and accordingly a blocking reclosing signal is sent to the tripped line protection; The odd harmonic ratio is used to characterize the mechanical state of the transformer during short-circuit impact; the odd harmonic ratio OHR is: ， In the formula, A 2i+1 is the 50Hz odd harmonic energy, A j It is 50Hz energy; Acoustic-to-current ratio PI: The ratio of sound pressure intensity to current under different currents. It is used to characterize the vibration intensity under different currents. The calculation process of the acoustic-to-current ratio PI is as follows: ， In the formula, V maxa is the average value of the maximum sound pressure amplitude in 1 second of data, I maxa is the maximum current average value in 1 second data, I n is the rated current of the transformer.

6. The transformer mechanical instability active protection device according to claim 5, characterized in that: When all the conditions of odd harmonic ratio less than 0.3, winding ratio change rate less than 0.01, and acoustic-current ratio less than 4.5 are met, the internal winding of the transformer is not deformed and the reclosing function of the line protection device operates normally.

7. The transformer mechanical instability active protection device according to claim 5 or 6, characterized in that: When the transformer current amplitude is less than 1.5 times the rated current and the vibration amplitude is less than 1.5 times the full-load vibration amplitude, the vibration characteristic quantity is extracted and the winding ratio change rate is calculated. The transformer vibration characteristic quantity, winding ratio change rate, oil temperature and oil pressure data are uploaded to the health management and control platform at a regular period to evaluate the mechanical state of the transformer winding online.

8. The transformer mechanical instability active protection device according to claim 7, characterized in that: The vibration characteristic quantities include frequency complexity, certainty, energy difference rate, vibration correlation level, odd harmonic ratio, effective energy ratio, vibration acceleration peak-to-peak value and sound-to-flow ratio; Frequency complexity FCD: characterizes the dispersion of vibration energy in the frequency domain; When the transformer windings are deformed, mechanical instability will cause the vibration energy to be dispersed over more frequency components, and the FCD value will increase significantly. Deterministic DET: Characterizes the stability of the vibration signal in terms of periodicity, and its value is between 0 and 1. When the transformer winding is deformed, mechanical instability will increase the uncertainty of the system and generate random vibration, resulting in a decrease in the DET value. Energy difference rate (EDR): It characterizes the overall change relationship of vibration energy at each measuring point over time, and its value is between 0 and 1. When the transformer winding is deformed, the EDR value will suddenly increase. Vibration correlation level VCL: It characterizes the correlation degree of vibration between each measuring point, and its value is between 0 and 1. For a normal transformer, the change mode of vibration signals at each measuring point is highly similar, and the VCL value is close to 1. When the transformer has winding deformation and mechanical instability, the vibration characteristics of each measuring point change, the consistency is weakened, and the VCL value decreases accordingly. Effective Energy Ratio (EER): refers to the ratio of the integral multiple system frequency energy to the total vibration energy, which is used to reflect the degree of external interference on the transformer tank surface vibration. When the transformer is seriously interfered by external interference, the EER will decrease. Vibration acceleration peak-to-peak value PPV: Characterizes the surface vibration intensity of the transformer, and measures 1 second vibration data every 5 minutes.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

Images