A Test Method and System for the Vibration Location of Transformer Based on Dynamic Stray Current Intrusion

Abstract

This invention discloses a testing method and system for detecting the vibration location of a transformer based on dynamic stray current intrusion. The method includes the following steps: synchronously sampling to obtain test data as required; performing discrete Fourier transform on the vibration acceleration sensor data in the test data to obtain the spectral distribution of vibration acceleration and obtain the spectral displacement components at different locations of the transformer; calculating the maximum positive displacement envelope and the maximum negative displacement envelope at each different location; obtaining the amplitude at each different location; performing a delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current; outputting the delay time of vibration caused by the dynamic stray current; and finally, analyzing the correlation between stray current and vibration displacement alarm / early warning information, and providing relevant suggestions for transformer vibration displacement monitoring. This invention obtains more accurate data by installing multiple z-axis vibration acceleration sensors on various surfaces of the transformer tank.

Description

Technical Field

[0001] This invention relates to the field of substation testing technology, specifically to a testing method and system based on the vibration location of a transformer caused by dynamic stray current intrusion. Background Technology

[0002] Excessive transformer vibration displacement can manifest as intensified localized vibration leading to loosening of the internal structure, thereby inducing a series of electrical and mechanical faults. This increases the probability of power outages for maintenance due to transformer failure caused by electrical or mechanical faults. Severely excessive transformer vibration displacement can damage internal components, further extending the duration and scope of power outages.

[0003] Under normal circumstances, the vibration displacement of a transformer is generated by the load current and is only a few micrometers. In some cases, the vibration displacement of a transformer may exceed the standard by 10 micrometers or more. In particular, transformers with large loads often exhibit larger vibration displacements when dynamic stray currents intrude.

[0004] The main structure of a transformer is a large enclosure-plate-spring-block structure, and the principle behind its vibration displacement is quite complex, requiring accurate analysis and early warning through monitoring methods. Research and analysis of vibration displacement caused by dynamic stray currents are still in their early stages, and related theoretical methods and testing techniques need further development. Therefore, research on experimental methods and systems for transformer vibration displacement under the influence of dynamic stray currents is essential. With the rapid development of IoT technology, how to combine IoT technology with the testing of transformer dynamic stray current-vibration displacement is also a worthwhile engineering problem to study. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a testing method and system for detecting the vibration location of a transformer based on dynamic stray current intrusion, aiming to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a test method for determining the vibration location of a transformer based on dynamic stray current intrusion, comprising the following steps:

[0007] Step S1: Obtain dynamic stray current data at the transformer neutral point, as well as synchronous data of vibration acceleration at different locations on the transformer;

[0008] Step S2: Perform a discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum;

[0009] Step S3: Obtain the spectral displacement components at different locations of the transformer based on the vibration acceleration spectrum;

[0010] Step S4: Based on the spectral displacement components at different locations of the transformer, calculate the change of vibration displacement at different locations of the transformer over time;

[0011] Step S5: Based on the set time interval of the dynamic stray current data, calculate the maximum positive displacement envelope and the maximum negative displacement envelope at each different position of the transformer to obtain the amplitude at each different position;

[0012] Step S6: Based on the maximum amplitude at different locations of the transformer, provide corresponding alarm or warning information;

[0013] Step S7: Perform a delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and output the delay time of vibration caused by the dynamic stray current.

[0014] Step S8: Analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information;

[0015] Step S9: Provide relevant suggestions for transformer vibration displacement monitoring.

[0016] Furthermore, the specific process of step S1 is as follows:

[0017] Step S1.1: Select the target transformer to be studied as the test object, install a stray current sensor on the transformer grounding neutral point circuit, and connect the stray current sensor to the first channel of the 16-channel synchronous data acquisition system.

[0018] Step S1.2: Select three facades on the transformer housing other than the radiator side for vibration acceleration measurement. Set five z-axis vibration acceleration sensors on each facade. Connect the 15 z-axis vibration acceleration sensors set on the three facades to channels 2 to 16 of the 16-channel synchronous data acquisition system.

[0019] Step S1.3: The 16-channel synchronous data acquisition system, based on a sampling rate of 16kHz, synchronously monitors dynamic stray current and channel vibration acceleration through stray current sensors and z-axis vibration acceleration sensors, and continuously stores dynamic stray current data and vibration acceleration data for more than 24 hours.

[0020] The five z-axis vibration acceleration sensors installed on each facade are arranged in the same way. Two and three z-axis vibration acceleration sensors are arranged horizontally at equal intervals at 50% and 90% of the height from the bottom of the facade, respectively, along the vertical centerline of each facade. The distance between the two z-axis vibration acceleration sensors at 50% of the height from the bottom of the facade is 90% of the facade width. Among the three z-axis vibration acceleration sensors at 90% of the height from the bottom of the facade, the distance between two adjacent z-axis vibration acceleration sensors is 45% of the facade width.

[0021] Further, the specific process of step S2 is as follows: Discrete Fourier transform is performed on the vibration acceleration data acquired from channels 2 to 16 of the 16-channel synchronous data acquisition system to obtain the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16; the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16 is expressed as a1(f n )~a 15 (f n ), where a x (f n ) represents the (x+1)th channel with respect to the frequency range f n The vibration acceleration spectrum, x = 1, 2, ..., 15, f n ∈[10Hz,2000Hz].

[0022] Furthermore, the specific process of step S3 is as follows: for a1(f n )~a 15 (f n ) is calculated to obtain a1(f n )~a 15 (f n The spectral shift component p1(f) n )~p 15 (f n ):

[0023]

[0024] In the formula, p x (f n (x+1) represents the spectral displacement component of the vibration acceleration spectrum of the (x+1)th channel with respect to the frequency range fn.

[0025] In step S4, the change in vibration displacement p(t) at different locations of the transformer over time is calculated as follows:

[0026] p x (t k ) = IFFT[p x (f n)],k=1,2,…,1382400000,x=1,2,…,15(2);

[0027] In the formula, IFFT is the inverse transform function p of the discrete Fourier transform. x (t k ) indicates that the xth position (measuring point) of the transformer is at t k The vibration displacement at time t; k represents the time series number t; t k This represents the k-th value of the time series t.

[0028] Furthermore, in step S5, the formula for calculating the maximum positive displacement envelope is:

[0029] P x+ (T m ) = max(p x (t k m=1,2,…,864000,t k ∈[0.1(m-1),0.1m),x=1,2,…,15(3);

[0030] In the formula, T m This indicates the set time interval based on dynamic stray current data; the set time for dynamic stray current data is 0.1s. P x+ (T m () represents the maximum positive displacement of position x at time Tm; m represents the number of the stray current monitoring time series T;

[0031] The formula for calculating the maximum negative displacement envelope is:

[0032] P x- (T m ) = min(p x (t k m=1,2,…,864000,t k ∈[0.1(m-1),0.1m),x=1,2,…,15(4);

[0033] In the formula, P x- (T m () represents the maximum negative displacement of position x at time Tm;

[0034] The formula for calculating the amplitude H at different locations is:

[0035] H x (T m ) = P x+ (T m )-P x- (T m ),x=1,2,…,15(5);

[0036] In the formula, H x (T m ) represents the maximum amplitude at position x at time Tm.

[0037] Furthermore, the specific process of step S6 is as follows:

[0038] Step S6.1: Vibration displacement exceeding the limit alarm;

[0039] If the amplitude is greater than 10μm for 1 minute or more than 30 minutes in total throughout the day, it indicates that the transformer vibration exceeds the standard. The location of the exceedance is recorded, and the corresponding vibration acceleration sensor will flash red and issue an alarm message.

[0040] Step S6.2: Vibration displacement early warning;

[0041] If the vibration displacement does not exceed the standard, but the amplitude lasts for 1 minute or accumulates for more than 30 minutes throughout the day, and the maximum displacement is greater than 7.5μm, it indicates that the transformer vibration exceeds the standard. Record the location of the exceedance, and the corresponding vibration acceleration sensor will flash yellow to issue a warning message.

[0042] Step S6.3: Vibration displacement normal indication;

[0043] When the vibration displacement is within the normal range, it indicates that the transformer vibration index is normal, and the corresponding vibration acceleration sensor green light will flash.

[0044] Furthermore, the specific process of step S7 is as follows:

[0045] Step S7.1: Calculate the delay correlation of the maximum positive displacement envelope with respect to the dynamic stray current;

[0046] Step S7.11: Obtain the lag time t d For 0 seconds, the maximum positive displacement envelope data P x+ (T m ) and the corresponding dynamic stray current I(T) m The correlation coefficient R) x+ (t d ), where R x+ (t d The initial value is 0, and x = 1, 2, ..., 15;

[0047] Step S7.12: Calculate P x+ (T m ) and the corresponding dynamic stray current I(T) m -t d The correlation coefficient R′ x+ (T m ), x = 1, 2, ..., 15, the calculation formula is:

[0048]

[0049] In the formula, P x+ For P x+ (T m The average value of ) For I(T) m The average value of )

[0050] When R x+ (T m ) less than R′ x+ (T m ),but:

[0051] R x+ (T m ) = R x ′ + (T m (7);

[0052] Step S7.13: Let t d =0.1+t d ;

[0053] Step S7.14: Determine t d If the value is greater than 60s, then the calculation of the delay correlation degree of the maximum positive displacement envelope with respect to the dynamic stray current ends, and R is output. x+ (T m ) and the lag time t of the maximum positive displacement d+ Otherwise, proceed to step S7.12;

[0054] Step 7.2: Calculate the delay correlation of the maximum negative displacement envelope with respect to the dynamic stray current;

[0055] Step S7.21: Obtain the lag time t d For 0 seconds, the maximum negative displacement envelope data P x- (T m ) and the corresponding dynamic stray current I(T) m The correlation coefficient R) x- (t d ), where R x- (t d The initial value is 0;

[0056] Step S7.22: Calculate P x- (T m ) and the corresponding dynamic stray current I(T) m -t d The correlation coefficient R′ x- (T m ), x = 1, 2, ..., 15, the calculation formula is:

[0057]

[0058] In the formula, P x- For P x- (T m The average value of ), where j represents the number of the time series throughout the day;

[0059] When R x- (T m ) less than R′ x- (T m ),but:

[0060] R x- (T m ) = R x ′ - (T m (9);

[0061] Step S7.23: Let t d =0.1+t d ;

[0062] Step S7.24: Determine t d If the value is greater than 60s, then the calculation of the delay correlation degree of the maximum negative displacement envelope with respect to the dynamic stray current ends, and R is output. x- (T m ) and the lag time t of the maximum negative displacement d- Otherwise, proceed to step S7.22;

[0063] Step S7.3: Delay time T of oscillation caused by output dynamic stray current D =0.5(t) d+ +t d- ).

[0064] Furthermore, the specific process of step S8 is as follows:

[0065] Step S8.1: Analyze the correlation between dynamic stray current and vibration displacement alarm cases;

[0066] Step S8.11: Obtain the alarm time period T B The correlation coefficient curve R between the maximum positive displacement envelope data and the dynamic stray current. x+ (T B Maximum negative displacement envelope data R x- (T B The correlation coefficient curve between ) and dynamic stray current;

[0067] Step S8.12: Calculate the correlation R between dynamic stray current and vibration displacement alarm cases. B :

[0068]

[0069] In the formula, dt represents the integration time;

[0070] Step S8.13: Output the correlation between dynamic stray current and vibration displacement alarm cases;

[0071] correlation degree R B >30% indicates a strong correlation;

[0072] correlation degree R B Vibration displacement alarm occurs when the actual load of the transformer and the dynamic stray current act together, between 10% and 30%.

[0073] correlation degree R B If the value is less than 10%, the correlation between dynamic stray current and vibration displacement alarm is weak.

[0074] Step S8.2: Analyze the correlation between stray current and vibration displacement early warning;

[0075] Step S8.21: Obtain the warning time period T Y The correlation coefficient curve R between the maximum negative displacement envelope data and the dynamic stray current. x+ (T Y Maximum negative displacement envelope data R x- (T Y The correlation coefficient curve between ) and dynamic stray current;

[0076] Step S8.22: Calculate the correlation R between stray current and vibration displacement early warning cases. Y :

[0077]

[0078] Step S8.23: Output the correlation between dynamic stray current and vibration displacement early warning cases;

[0079] correlation degree R Y Vibration displacement early warning under the combined effect of the actual load and dynamic stray current of the transformer, between 10% and 30%;

[0080] correlation degree R Y If the value is less than 10%, the correlation between dynamic stray current and vibration displacement early warning is not strong.

[0081] Furthermore, in step S9, the following suggestions are given regarding transformer vibration displacement monitoring:

[0082] Step S9.1: If the correlation between vibration displacement alarm and dynamic stray current is not strong, then do not install z-axis vibration acceleration sensor and stray current sensor;

[0083] Step S9.2: When there is a strong correlation between the vibration displacement alarm and the dynamic stray current, the z-axis vibration acceleration sensor is no longer installed. Instead, a stray current sensor is installed directly at the transformer neutral point. The dynamic stray current data is multiplied by the correlation degree R. B Issue an alarm for excessive vibration acceleration and displacement.

[0084] Step S9.3: If there is a strong correlation between the vibration displacement warning and the dynamic stray current, then the z-axis vibration acceleration sensor is no longer installed. Instead, a stray current sensor is installed directly at the transformer neutral point, and the dynamic stray current data is multiplied by the correlation degree R. Y Provide early warning of vibration acceleration and displacement;

[0085] Step S9.4: When vibration displacement alarm is triggered by the combined effect of the actual load of the transformer and dynamic stray current, investigate the actual load curve of the transformer and perform alarm analysis.

[0086] Step S9.5: When vibration displacement warning is performed under the combined effect of the actual load and dynamic stray current of the transformer, the actual load curve of the transformer is investigated and a warning analysis is performed.

[0087] Step S9.6: Provide relevant suggestions for transformer vibration and displacement monitoring on the client, cloud and mobile terminals through Internet of Things (IoT) technology.

[0088] A test system based on the vibration location of a transformer intrusion caused by dynamic stray currents, applied to test methods based on the vibration location of a transformer intrusion caused by dynamic stray currents, including:

[0089] The acquisition module is used to acquire dynamic stray current data at the neutral point of the transformer, as well as synchronous data of vibration acceleration at different locations of the transformer;

[0090] The transformation module is used to perform discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum;

[0091] The component calculation module is used to obtain the spectral displacement components at different positions of the transformer based on the vibration acceleration spectrum.

[0092] The variation calculation module is used to calculate the change of vibration displacement of the transformer at different locations over time based on the spectral displacement components at different locations of the transformer.

[0093] The amplitude calculation module is used to calculate the maximum positive displacement envelope and the maximum negative displacement envelope of the transformer at different positions based on a set time interval of dynamic stray current data, so as to obtain the amplitude at different positions.

[0094] The alarm and early warning module is used to provide corresponding alarm or early warning information based on the maximum amplitude at different locations of the transformer;

[0095] The delay correlation analysis module is used to perform delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and outputs the delay time of vibration caused by the dynamic stray current.

[0096] The alarm and early warning correlation analysis module is used to analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information.

[0097] The suggestion module is used to provide relevant suggestions for transformer vibration and displacement monitoring.

[0098] Compared with existing technologies, the present invention has the following advantages: By installing multiple z-axis vibration acceleration sensors on various surfaces of the transformer tank, the present invention collects more accurate data. By analyzing the correlation between stray current and vibration displacement alarm / early warning information, relevant suggestions for transformer vibration displacement monitoring can be given, effectively solving the transformer vibration displacement problem. Attached Figure Description

[0099] Figure 1 This is a flowchart of the method of the present invention.

[0100] Figure 2 This is a diagram showing the arrangement of the z-axis vibration acceleration sensor of the present invention. Detailed Implementation

[0101] like Figure 1 As shown, the present invention provides a technical solution: a test method for determining the vibration location of a transformer based on dynamic stray current intrusion, comprising the following steps:

[0102] Step S1: Obtain dynamic stray current data at the transformer neutral point, as well as synchronous data of vibration acceleration at different locations on the transformer.

[0103] Step S1.1: Select the target transformer to be studied as the test object, install a stray current sensor on the transformer grounding neutral point circuit, and connect the stray current sensor to the first channel of the 16-channel synchronous data acquisition system.

[0104] Step S1.2: Select three facades of the transformer housing other than the radiator side for vibration acceleration measurement. Set five z-axis vibration acceleration sensors on each facade. Connect the 15 z-axis vibration acceleration sensors set on the three facades to channels 2 to 16 of the 16-channel synchronous data acquisition system.

[0105] The five z-axis vibration accelerometers on each facade are arranged identically. Two and three z-axis vibration accelerometers are positioned equidistantly laterally at 50% and 90% of the height from the bottom of the facade, respectively, along the vertical centerline of each facade. The distance between the two z-axis vibration accelerometers at 50% of the height from the bottom of the facade is 90% of the facade width. The distance between adjacent z-axis vibration accelerometers at 90% of the height from the bottom of the facade is 45% of the facade width. Figure 2 As shown.

[0106] Step S1.3: The 16-channel synchronous data acquisition system, based on a sampling rate of 16kHz, synchronously monitors dynamic stray current and channel vibration acceleration through stray current sensors and z-axis vibration acceleration sensors, and continuously stores dynamic stray current data and vibration acceleration data for more than 24 hours.

[0107] Step S2: Perform a discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum.

[0108] The specific process of step S2 is as follows: Discrete Fourier Transform (FFT) is performed on the vibration acceleration data acquired from channels 2 to 16 of the 16-channel synchronous data acquisition system to obtain the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16; the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16 is represented as a1(f n )~a 15 (f n ), where a x (f n ) represents the (x+1)th channel with respect to the frequency range f n The vibration acceleration spectrum, x = 1, 2, ..., 15, f n ∈[10Hz,2000Hz].

[0109] Step S3: Obtain the spectral displacement components at different positions of the transformer based on the vibration acceleration spectrum.

[0110] The specific process of step S3 is as follows: for a1(f n )~a 15 (f n ) is calculated to obtain a1(f n )~a 15 (f n The spectral shift component p1(f) n )~p 15 (f n ):

[0111]

[0112] In the formula, p x (f n ) represents the spectral displacement component of the vibration acceleration spectrum of the (x+1)th channel with respect to the frequency range fn.

[0113] Step S4: Based on the spectral displacement components at different locations of the transformer, calculate the change in vibration displacement p(t) at different locations of the transformer over time.

[0114] p x (t k ) = IFFT[p x (f n )],k=1,2,…,1382400000,x=1,2,…,15(2);

[0115] In the formula, IFFT is the inverse transform function of the discrete Fourier transform; p x (t k ) indicates that the xth position (measuring point) of the transformer is at t k The vibration displacement at time t; k represents the time series number t; t k This represents the k-th value of the time series t.

[0116] Step S5: Based on the 0.1s time interval T of the dynamic stray current data m The maximum positive and maximum negative displacement envelopes of the transformer at different locations (where the z-axis vibration acceleration sensor is installed) are calculated to obtain the amplitude at each location.

[0117] The formula for calculating the maximum positive displacement envelope is:

[0118] P x+ (T m ) = max(p x (t k m=1,2,…,864000,t k ∈[0.1(m-1),0.1m),x=1,2,…,15(3);

[0119] In the formula, P x+ (T m ) represents the maximum positive displacement of position x at time Tm; m represents the number of the stray current monitoring time series T.

[0120] The formula for calculating the maximum negative displacement envelope is:

[0121] P x- (T m ) = min(p x (t km=1,2,…,864000,t k ∈[0.1(m-1),0.1m),x=1,2,…,15(4);

[0122] In the formula, P x- (T m ) represents the maximum negative displacement of position x at time Tm.

[0123] The formula for calculating the amplitude H at different locations is:

[0124] H x (T m ) = P x+ (T m )-P x- (T m ),x=1,2,…,15(5);

[0125] In the formula, H x (T m ) indicates that position x is at time T m The maximum amplitude below.

[0126] Step S6: Based on the maximum amplitude at different locations of the transformer, provide corresponding alarm or warning information.

[0127] Step S6.1: Vibration displacement exceeds the limit alarm.

[0128] If the amplitude is greater than 10μm for 1 minute or more than 30 minutes in total throughout the day, it indicates that the transformer vibration exceeds the standard. The location of the exceedance will be recorded, and the corresponding vibration acceleration sensor will flash red and issue an alarm message.

[0129] Step S6.2: Vibration displacement early warning.

[0130] If the vibration displacement does not exceed the standard, but the amplitude lasts for 1 minute or accumulates for more than 30 minutes throughout the day, and the maximum displacement is greater than 7.5μm, it indicates that the transformer vibration exceeds the standard. The location of the exceedance is recorded, and the corresponding vibration acceleration sensor will flash yellow to issue a warning message.

[0131] Step S6.3: Vibration displacement normal indication.

[0132] If the vibration displacement is within the normal range, it indicates that the transformer vibration index is normal, and the corresponding vibration acceleration sensor green light will flash.

[0133] Step S7: Perform a delay correlation analysis on the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and output the delay time T of the vibration caused by the dynamic stray current. D .

[0134] Step S7.1: Calculate the delay correlation of the maximum positive displacement envelope with respect to the dynamic stray current.

[0135] Step S7.11: Obtain the lag time t d For 0 seconds, the maximum positive displacement envelope data P x+ (T m ) and the corresponding dynamic stray current I(T) m The correlation coefficient R) x+ (t d ), where R x+ (t d The initial value is 0, x = 1, 2, ..., 15.

[0136] Step S7.12: Calculate P x+ (T m ) and the corresponding dynamic stray current I(T) m -t d The correlation coefficient R′ x+ (T m ), x = 1, 2, ..., 15, the calculation formula is:

[0137]

[0138] In the formula, For P x+ (T m The average value of ) For I(T) m The average value of ).

[0139] If R x+ (T m ) less than R′ x+ (T m ),but:

[0140] R x+ (T m ) = R x ′ + (T m (7);

[0141] Step S7.13: Let t d =0.1+t d .

[0142] Step S7.14: Determine t d If the value is greater than 60s, then the calculation of the delay correlation of the maximum positive displacement envelope with respect to the dynamic stray current ends, and R is output. x+ (T m ) and the lag time t of the maximum positive displacement d+ Otherwise, proceed to step S7.12.

[0143] Step 7.2: Calculate the delay correlation of the maximum negative displacement envelope with respect to the dynamic stray current.

[0144] Step S7.21: Obtain the lag time t d For 0 seconds, the maximum negative displacement envelope data P x- (T m ) and the corresponding dynamic stray current I(T) m The correlation coefficient R) x- (t d ), where R x- (t d The initial value is 0.

[0145] Step S7.22: Calculate P x- (T m ) and the corresponding dynamic stray current I(T) m -t d The correlation coefficient R′ x- (T m ), x = 1, 2, ..., 15, the calculation formula is:

[0146]

[0147] In the formula, For P x- (T m The average value of ), where j represents the number of the time series throughout the day.

[0148] If R x- (T m ) less than R′ x- (T m ),but:

[0149] R x- (T m ) = R x ′ - (T m (9);

[0150] Step S7.23: Let t d =0.1+t d .

[0151] Step S7.24: Determine t d If the value is greater than 60s, then the calculation of the delay correlation of the maximum negative displacement envelope with respect to the dynamic stray current ends, and R is output. x- (T m ) and the lag time t of the maximum negative displacement d- Otherwise, proceed to step S7.22.

[0152] Step S7.3: Delay time T of oscillation caused by output dynamic stray current D =0.5(t) d+ +t d- ).

[0153] Step S8: Analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information.

[0154] Transformer vibration is closely related to the actual load fluctuations and stray currents intrusion into the transformer. Therefore, further analysis is needed to determine the factors that influence vibration displacement exceeding limits / early warnings.

[0155] Step S8.1: Analyze the correlation between dynamic stray current and vibration displacement alarm cases.

[0156] Step S8.11: Obtain the alarm time period T B The correlation coefficient curve R between the maximum positive displacement envelope data and the dynamic stray current. x+ (T B Maximum negative displacement envelope data R x- (T B The correlation coefficient curve between the current and the dynamic stray current.

[0157] Step S8.12: Calculate the correlation R between dynamic stray current and vibration displacement alarm cases. B :

[0158]

[0159] In the formula, dt represents the integration time.

[0160] Step S8.13: Output the correlation between dynamic stray current and vibration displacement alarm cases.

[0161] correlation degree R B A correlation of >30% is considered a strong association.

[0162] correlation degree R B If the value is between 10% and 30%, it is considered that the vibration displacement alarm is triggered by the combined effect of the actual load of the transformer and the dynamic stray current.

[0163] correlation degree R B If the value is less than 10%, the correlation between dynamic stray current and vibration displacement alarm is considered weak.

[0164] Step S8.2: Analyze the correlation between stray current and vibration displacement early warning.

[0165] Step S8.21: Obtain the warning time period T YThe correlation coefficient curve R between the maximum negative displacement envelope data and the dynamic stray current. x+ (T Y Maximum negative displacement envelope data R x- (T Y The correlation coefficient curve between the current and the dynamic stray current.

[0166] Step S8.22: Calculate the correlation R between stray current and vibration displacement early warning cases. Y :

[0167]

[0168] Step S8.23: Output the correlation between dynamic stray current and vibration displacement early warning cases.

[0169] correlation degree R Y If the value is between 10% and 30%, it is considered to be a vibration displacement warning under the combined effect of the actual load of the transformer and the dynamic stray current.

[0170] correlation degree R Y If the percentage is less than 10%, the correlation between dynamic stray current and vibration displacement early warning is considered to be weak.

[0171] Step S8.3: Output the analysis results to the client, cloud and mobile terminals through Internet of Things (IoT) technology.

[0172] Step S9: Provide relevant suggestions for transformer vibration displacement monitoring.

[0173] Considering factors such as weather, reliability, and electrical safety, vibration acceleration sensors should not be hung on the transformer facade for extended periods.

[0174] Step S9.1: If the correlation between vibration displacement alarm and dynamic stray current is not strong, then there is no need to install a z-axis vibration acceleration sensor and a stray current sensor.

[0175] Step S9.2: If there is a strong correlation between the vibration displacement alarm and the dynamic stray current, then there is no need to install a z-axis vibration acceleration sensor. Instead, install a stray current sensor directly at the transformer neutral point and calculate the dynamic stray current data by multiplying the correlation coefficient R. B An alarm will be triggered if the vibration acceleration and displacement exceed the limit.

[0176] Step S9.3: If there is a strong correlation between the vibration displacement warning and the dynamic stray current, then there is no need to install a z-axis vibration acceleration sensor. Instead, install a stray current sensor directly at the transformer neutral point and calculate the dynamic stray current data by multiplying the correlation coefficient R. Y Provide early warning of vibration acceleration and displacement.

[0177] Step S9.4: If the vibration displacement alarm is caused by the combined effect of the transformer's actual load and dynamic stray current, it is recommended to investigate the transformer's actual load curve for further alarm analysis.

[0178] Step S9.5: If the vibration displacement warning is due to the combined effect of the transformer's actual load and dynamic stray current, it is recommended to investigate the transformer's actual load curve for further warning analysis.

[0179] Step S9.6: Provide relevant suggestions for transformer vibration and displacement monitoring on the client, cloud and mobile terminals through Internet of Things (IoT) technology.

[0180] A test system based on the vibration location of a transformer intrusion caused by dynamic stray currents, applied to test methods based on the vibration location of a transformer intrusion caused by dynamic stray currents, including:

[0181] The acquisition module is used to acquire dynamic stray current data at the neutral point of the transformer, as well as synchronous data of vibration acceleration at different locations of the transformer;

[0182] The transformation module is used to perform discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum;

[0183] The component calculation module is used to obtain the spectral displacement components at different positions of the transformer based on the vibration acceleration spectrum.

[0184] The variation calculation module is used to calculate the change of vibration displacement of the transformer at different locations over time based on the spectral displacement components at different locations of the transformer.

[0185] The amplitude calculation module is used to calculate the maximum positive displacement envelope and the maximum negative displacement envelope of the transformer at different positions based on a set time interval of dynamic stray current data, so as to obtain the amplitude at different positions.

[0186] The alarm and early warning module is used to provide corresponding alarm or early warning information based on the maximum amplitude at different locations of the transformer;

[0187] The delay correlation analysis module is used to perform delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and outputs the delay time of vibration caused by the dynamic stray current.

[0188] The alarm and early warning correlation analysis module is used to analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information.

[0189] The suggestion module is used to provide relevant suggestions for transformer vibration and displacement monitoring.

[0190] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A test method for determining the vibration location of a transformer based on dynamic stray current intrusion, characterized in that, Includes the following steps: Step S1: Obtain dynamic stray current data at the transformer neutral point, as well as synchronous data of vibration acceleration at different locations on the transformer; Step S2: Perform a discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum; Step S3: Obtain the spectral displacement components at different locations of the transformer based on the vibration acceleration spectrum; Step S4: Based on the spectral displacement components at different locations of the transformer, calculate the change of vibration displacement at different locations of the transformer over time; Step S5: Based on the set time interval of the dynamic stray current data, calculate the maximum positive displacement envelope and the maximum negative displacement envelope at each different position of the transformer to obtain the amplitude at each different position; Step S6: Based on the maximum amplitude at different locations of the transformer, provide corresponding alarm or warning information; Step S7: Perform a delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and output the delay time of vibration caused by the dynamic stray current. Step S8: Analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information; Step S9: Provide suggestions for transformer vibration displacement monitoring; The specific process of step S1 is as follows: Step S1.1: Select the target transformer to be studied as the test object, install a stray current sensor on the transformer grounding neutral point circuit, and connect the stray current sensor to the first channel of the 16-channel synchronous data acquisition system. Step S1.2: Select three facades of the transformer housing (excluding the radiator side) for vibration acceleration measurement. Set five z-axis vibration acceleration sensors on each facade, for a total of 15 sensors on the three facades. The shaft vibration acceleration sensors are connected to channels 2 through 16 of the 16-channel synchronous data acquisition system. Step S1.3: The 16-channel synchronous data acquisition system, based on a sampling rate of 16kHz, uses a stray current sensor and The shaft vibration acceleration sensor performs synchronous monitoring of dynamic stray current and channel vibration acceleration, and continuously stores dynamic stray current data and vibration acceleration data for more than 24 hours. Five of them are set on each facade. The shaft vibration acceleration sensors are arranged in the same way, with two and three equidistantly arranged laterally at positions 50% and 90% of the height from the bottom of the facade, respectively, along the vertical centerline of each facade. Shaft vibration acceleration sensors, including two located at a height of 50% from the bottom of the facade. The distance between the shaft vibration acceleration sensors is 90% of the facade width, and the three sensors are located at 90% of the height from the bottom of the facade. In shaft vibration acceleration sensors, two adjacent The distance between shaft vibration acceleration sensors is 45% of the facade width; The specific process of step S2 is as follows: Discrete Fourier transform is performed on the vibration acceleration data acquired from channels 2 to 16 of the 16-channel synchronous data acquisition system to obtain the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16; the vibration acceleration spectrum of the acquired vibration acceleration data from channels 2 to 16 is expressed as... ,in, For the first Channel with respect to frequency range The vibration acceleration spectrum , ; The specific process of step S3 is as follows: For Calculations were performed to obtain spectral shift component p1(f n )~p 15 (f n ): （1）； In the formula, For the first Channel with respect to frequency range The spectral displacement component of the vibration acceleration spectrum; In step S4, the change of vibration displacement at different locations of the transformer over time is calculated. Represented as: （2）； Where, The inverse transform function of the discrete Fourier transform Indicates the transformer number The location of measuring point No. is at The vibration displacement at any given moment; Representing time series serial number; Representing time series The Values.

2. The test method for determining the vibration location of a transformer based on dynamic stray current intrusion as described in claim 1, characterized in that: In step S5, the formula for calculating the maximum positive displacement envelope is: （3）； Where, This indicates the set time interval based on dynamic stray current data, where the set time for dynamic stray current data is 0.1s; Indicates the first Position number at time The maximum positive displacement below; Represents stray current monitoring time series The number; The formula for calculating the maximum negative displacement envelope is: （4）； In the formula, Indicates the first Position number at time The maximum negative displacement below; Amplitude at different locations The calculation formula is: （5）； Where, Indicates the first Position number at time The maximum amplitude below.

3. The test method for determining the vibration location of a transformer based on dynamic stray current intrusion as described in claim 2, characterized in that: The specific process of step S6 is as follows: Step S6.1: Vibration displacement exceeding the limit alarm; If the amplitude is greater than 10μm for 1 minute or more than 30 minutes in total throughout the day, it indicates that the transformer vibration exceeds the standard. The location of the exceedance is recorded, and the corresponding vibration acceleration sensor will flash red and issue an alarm message. Step S6.2: Vibration displacement early warning; If the vibration displacement does not exceed the standard, but the amplitude lasts for 1 minute or accumulates for more than 30 minutes throughout the day, and the maximum displacement is greater than 7.5μm, it indicates that the transformer vibration exceeds the standard. Record the location of the exceedance, and the corresponding vibration acceleration sensor will flash yellow to issue a warning message. Step S6.3: Vibration displacement normal indication; When the vibration displacement is within the normal range, it indicates that the transformer vibration index is normal, and the corresponding vibration acceleration sensor green light will flash.

4. The test method for determining the vibration location of a transformer based on dynamic stray current intrusion as described in claim 3, characterized in that: The specific process of step S7 is as follows: Step S7.1: Calculate the delay correlation of the maximum positive displacement envelope with respect to the dynamic stray current; Step S7.11: Obtain the lag time Maximum positive displacement envelope data (0 seconds) With the corresponding dynamic stray current correlation coefficient ,in, The initial value is 0. ; Step S7.12: Calculation With the corresponding dynamic stray current correlation coefficient , , the calculation formula is: （6）； Where, for The average value of for The average value; when Less than ,but: （7）； Step S7.13: Let ; Step S7.14: Determine If the value is greater than 60 seconds, then the calculation of the delay correlation of the maximum positive displacement envelope with respect to the dynamic stray current ends, and the output is given. Lag time with maximum positive displacement Otherwise, proceed to step S7.12; Step 7.2: Calculate the delay correlation of the maximum negative displacement envelope with respect to the dynamic stray current; Step S7.21: Obtain the lag time Data for the maximum negative displacement envelope at 0 seconds. With the corresponding dynamic stray current correlation coefficient ,in, The initial value is 0; Step S7.22: Calculation With the corresponding dynamic stray current correlation coefficient , , the calculation formula is: （8）； In the formula, for The average value; when Less than ,but: （9）； Step S7.23: Let ; Step S7.24: Determine If the value is greater than 60 seconds, then the calculation of the delay correlation of the maximum negative displacement envelope with respect to the dynamic stray current ends, and the output is given. Lag time with maximum negative displacement Otherwise, proceed to step S7.22; Step S7.3: Delay time of oscillation caused by output dynamic stray current .

5. The test method for determining the vibration location of a transformer based on dynamic stray current intrusion according to claim 4, characterized in that: The specific process of step S8 is as follows: Step S8.1: Analyze the correlation between dynamic stray current and vibration displacement alarm cases; Step S8.11: Obtain the alarm time period Correlation curve between maximum positive displacement envelope data and dynamic stray current Correlation coefficient curve between maximum negative displacement envelope data and dynamic stray current ; Step S8.12: Calculate the correlation between dynamic stray current and vibration displacement alarm cases. : （10）； In the formula, Indicates the integration time; Step S8.13: Output the correlation between dynamic stray current and vibration displacement alarm cases; correlation >30% indicates a strong correlation; correlation degree R B Vibration displacement alarm occurs when the actual load of the transformer and the dynamic stray current are both at a rate between 10% and 30%. correlation degree R B If the value is less than 10%, the correlation between dynamic stray current and vibration displacement alarm is weak. Step S8.2: Analyze the correlation between stray current and vibration displacement early warning; Step S8.21: Obtain the warning time period T Y The correlation coefficient curve between the maximum negative displacement envelope data and the dynamic stray current. Correlation coefficient curve between maximum negative displacement envelope data and dynamic stray current ; Step S8.22: Calculate the correlation between stray current and vibration displacement early warning cases. : （11）； Step S8.23: Output the correlation between dynamic stray current and vibration displacement early warning cases; correlation Vibration displacement early warning under the combined effect of the actual load and dynamic stray current of the transformer, between 10% and 30%; correlation If the value is less than 10%, the correlation between dynamic stray current and vibration displacement early warning is not strong.

6. The test method for determining the vibration location of a transformer based on dynamic stray current intrusion according to claim 5, characterized in that: In step S9, the following suggestions are given for monitoring transformer vibration displacement: Step S9.1: If the correlation between vibration displacement alarm and dynamic stray current is weak, then do not install it. Shaft vibration acceleration sensor and stray current sensor; Step S9.2: When there is a strong correlation between the vibration displacement alarm and the dynamic stray current, no further installation is required. A shaft vibration acceleration sensor is used, and a stray current sensor is installed directly at the transformer neutral point. The dynamic stray current data is multiplied by the correlation coefficient. Issue an alarm for excessive vibration acceleration and displacement. Step S9.3: If there is a strong correlation between vibration displacement warning and dynamic stray current, then installation is no longer required. A shaft vibration acceleration sensor is used, and a stray current sensor is installed directly at the transformer neutral point. The dynamic stray current data is multiplied by the correlation coefficient. Provide early warning of vibration acceleration and displacement; Step S9.4: When vibration displacement alarm is triggered by the combined effect of the actual load of the transformer and dynamic stray current, investigate the actual load curve of the transformer and perform alarm analysis. Step S9.5: When vibration displacement warning is performed under the combined effect of the actual load and dynamic stray current of the transformer, the actual load curve of the transformer is investigated and a warning analysis is performed. Step S9.6: Provide suggestions for transformer vibration and displacement monitoring on the client, cloud, and mobile terminals through Internet of Things (IoT) technology.

7. A test system for determining the vibration location of a transformer based on dynamic stray current intrusion, applied to the test method for determining the vibration location of a transformer based on dynamic stray current intrusion as described in any one of claims 1-6, characterized in that, include: The acquisition module is used to acquire dynamic stray current data at the neutral point of the transformer, as well as synchronous data of vibration acceleration at different locations of the transformer; The transformation module is used to perform discrete Fourier transform on the acquired vibration acceleration data to obtain the vibration acceleration spectrum; The component calculation module is used to obtain the spectral displacement components at different positions of the transformer based on the vibration acceleration spectrum. The variation calculation module is used to calculate the change of vibration displacement of the transformer at different locations over time based on the spectral displacement components at different locations of the transformer. The amplitude calculation module is used to calculate the maximum positive displacement envelope and the maximum negative displacement envelope of the transformer at different positions based on a set time interval of dynamic stray current data, so as to obtain the amplitude at different positions. The alarm and early warning module is used to provide corresponding alarm or early warning information based on the maximum amplitude at different locations of the transformer; The delay correlation analysis module is used to perform delay correlation analysis of the maximum positive displacement envelope and the maximum negative displacement envelope with respect to the dynamic stray current, and outputs the delay time of vibration caused by the dynamic stray current. The alarm and early warning correlation analysis module is used to analyze the correlation between dynamic stray current and vibration displacement alarm information, and the correlation between dynamic stray current and vibration displacement early warning information. The suggestion module is used to provide suggestions for monitoring transformer vibration and displacement.

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