Method and device for evaluating the degree of harmonic interference of a variable frequency drive source with vibration signals

Abstract

The application provides a method and device for evaluating the harmonic interference degree of a converter transformer by using a vibration signal. The method comprises the following steps: collecting multiple vibration signals collected by multiple vibration sensors as vibration samples; obtaining the frequency spectrum of each vibration sample; constructing a discrete frequency spectrum sequence of the vibration sample by using the amplitude of a preset reference frequency and its multiple frequencies in the frequency spectrum of the vibration sample; identifying the effective local peak value of the discrete frequency spectrum sequence of each vibration sample; calculating the energy concentration degree feature and the energy distribution entropy feature of the vibration sample based on the effective local peak value; and finally evaluating the harmonic interference degree of the converter transformer at the current moment according to the energy concentration degree feature and the energy distribution entropy feature of each vibration sample. The scheme evaluates the harmonic interference degree of the converter transformer by using the vibration signal, thereby preventing the converter transformer from malfunctioning due to excessive harmonic interference.

Description

Technical Field

[0001] This invention relates to the field of converter transformer monitoring technology, and in particular to a method and apparatus for assessing the degree of harmonic interference from the excitation source of a converter transformer using vibration signals. Background Technology

[0002] As a key piece of equipment in DC transmission systems, converter transformers play an important role in isolating AC and DC power grids and exchanging energy. Their safety and reliability are closely related to the operational reliability of DC transmission and transformation systems.

[0003] However, in actual operation, it has been found that the failure rate of high-voltage DC converter transformers is approximately twice that of transformers in AC power systems. This is because the operating conditions of converter transformers are significantly different from those of AC power transformers; their valve-side windings are subjected to the combined effects of multiple electrical excitation sources, including power frequency and high-order harmonics. Therefore, real-time monitoring and assessment of the harmonic interference levels of the electrical excitation sources of converter transformers are crucial prerequisites for ensuring their safe and stable operation.

[0004] Existing converter transformer monitoring technologies generally ignore harmonic interference experienced by the converter transformer and directly determine whether the converter transformer has a fault based on its vibration characteristics.

[0005] Therefore, how to assess the degree of harmonic interference on converter transformers has become an urgent problem to be solved in the field of converter transformer monitoring. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a method and apparatus for assessing the degree of harmonic interference from the excitation source of a converter transformer using vibration signals, thereby providing a way to monitor the degree of harmonic interference experienced by the converter transformer in real time.

[0007] The first aspect of this application provides a method for evaluating the degree of harmonic interference from a converter transformer excitation source using vibration signals, comprising:

[0008] Multiple vibration samples of the converter transformer at the current moment are collected; wherein each vibration sample is a vibration signal collected by a vibration sensor installed on the outer surface of the converter transformer.

[0009] For each vibration sample, a discrete spectrum sequence of the vibration sample is constructed using the amplitude of the preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform.

[0010] For each vibration sample, identify each effective local peak in the discrete spectral sequence of the vibration sample;

[0011] For each vibration sample, the energy concentration characteristic of the vibration sample is calculated based on the effective local peak value corresponding to the vibration sample.

[0012] For each vibration sample, the energy distribution entropy characteristics of the vibration sample are calculated based on the effective local peak value and the frequency corresponding to the effective local peak value.

[0013] The degree of harmonic interference to the converter transformer at the current moment is assessed based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample.

[0014] A second aspect of this application provides an apparatus for evaluating the degree of harmonic interference from a converter transformer excitation source using vibration signals, comprising:

[0015] The acquisition unit is used to acquire multiple vibration samples of the converter transformer at the current moment; wherein each vibration sample is a vibration signal acquired by a vibration sensor installed on the outer surface of the converter transformer.

[0016] The construction unit is used to construct a discrete spectrum sequence of each vibration sample by using the amplitude of a preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform.

[0017] The identification unit is used to identify each effective local peak in the discrete spectrum sequence of each vibration sample.

[0018] A concentration calculation unit is used to calculate the energy concentration characteristics of each vibration sample based on the effective local peak value corresponding to the vibration sample.

[0019] The distribution entropy calculation unit is used to calculate the energy distribution entropy characteristics of each vibration sample based on the effective local peak value and the frequency corresponding to the effective local peak value.

[0020] The evaluation unit is used to evaluate the degree of harmonic interference to the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample.

[0021] This application provides a method and apparatus for assessing the degree of harmonic interference of a converter transformer excitation source using vibration signals. The method includes: using multiple vibration signals collected by multiple vibration sensors as vibration samples; acquiring the spectrum of each vibration sample; constructing a discrete spectrum sequence of the vibration samples using a preset reference frequency and the amplitude of its harmonics in the spectrum of the vibration samples; identifying the effective local peaks in the discrete spectrum sequence of each vibration sample; calculating the energy concentration characteristics and energy distribution entropy characteristics of the vibration sample based on the effective local peaks; and finally assessing the degree of harmonic interference on the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample. This scheme assesses the degree of harmonic interference on the converter transformer through vibration signals, thereby preventing the converter transformer from failing due to excessive harmonic interference. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 A flowchart illustrating a method for evaluating the degree of harmonic interference from a converter transformer excitation source using vibration signals, provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of a device for evaluating the degree of harmonic interference of a converter transformer excitation source using vibration signals, provided in an embodiment of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1 The following is a flowchart of a method for evaluating the degree of harmonic interference of a converter transformer excitation source using vibration signals, provided in an embodiment of this application. The method may include the following steps.

[0027] S101 collects multiple vibration samples of the converter transformer at the current moment.

[0028] Each vibration sample is a vibration signal collected by a vibration sensor installed on the outer surface of the converter transformer.

[0029] For example, the sampling time for each sample can be set to T seconds. Then, in step S101, each vibration sensor can start from the current moment and continuously sample at the sampling frequency f within T seconds to obtain a vibration signal lasting for T seconds. This vibration signal is a vibration sample obtained by the vibration sensor in this sampling. T can be set to a value greater than 0.02 seconds, and its specific value can be set according to the situation and is not limited.

[0030] It should be noted that the method provided in this embodiment can be executed periodically at intervals of Δt to achieve the effect of periodically detecting the degree of harmonic interference to the converter transformer. Δt should be greater than 1 minute.

[0031] For example, the method in this embodiment can be set to be executed once every 30 minutes, that is, Δt is set to be equal to 30 minutes. Then, multiple vibration sensors installed on the outer surface of the converter transformer can collect multiple vibration samples every 30 minutes according to step S101. Then, these vibration samples are analyzed through subsequent steps to determine the degree of harmonic interference on the converter transformer during this sampling.

[0032] In step S101, the number of sensors can be denoted as K, where K is a natural number greater than 1. Its specific value can be set as needed and is not limited.

[0033] In some alternative embodiments, a current sensor may also be installed on the line of the converter transformer to synchronously acquire the current signal of the converter transformer during the sampling time when S101 is executed.

[0034] S102, For each vibration sample, construct a discrete spectrum sequence of the vibration sample using the amplitude of the preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform.

[0035] A vibration sample can be denoted as v m，n =[v m，n (0), v m，n (1 / f)……v m，n (T)]. Where v m，n This indicates that the vibration sample is a vibration sample obtained from the m-th sampling of the n-th vibration sensor during the day, v m，n (0) represents the first signal value sampled by the vibration sensor after the start of this sampling, v m，n (1 / f) represents the second signal value obtained after a time interval of 1 / f, and so on, v m，n (T) represents the last signal value obtained after T seconds from the start of this sampling.

[0036] In step S102, a P-point discrete Fourier transform can be performed on each vibration sample, where P is a preset positive integer. For any vibration sample v m，n After performing a discrete Fourier transform at point P, the transformed vibration sample V can be obtained as shown in the following formula (1). m，n .

[0037]

[0038] Where L is equal to the integer obtained by rounding down the ratio of the sampling time to the sampling frequency.

[0039] Based on the transformed vibration sample, the amplitude of the reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample can be extracted using the following formula (2):

[0040]

[0041] Formula (2) is illustrated using a reference frequency of 50Hz as an example. In some optional embodiments, the reference frequency can be changed to other frequencies as needed, without limitation.

[0042] k l The formula k can be used l =round(50 / f*S*l) is calculated, where l is a natural number greater than or equal to 1. The round() function indicates that the value within the parentheses is rounded to the nearest integer.

[0043] In formula (2) V m，n，50l This represents the amplitude at l times the reference frequency.

[0044] The transformed vibration sample V can be obtained by combining several amplitude values ​​extracted according to the above formula (2). m，n The corresponding discrete spectrum sequence can be represented by the following formula (3):

[0045]

[0046] It can be seen that each value in this discrete spectrum sequence corresponds to a frequency, for example, V. m，n，50 The corresponding frequency is 50Hz, V m，n，100 The corresponding frequency is 100Hz.

[0047] S103, for each vibration sample, identify each effective local peak in the discrete spectrum sequence of the vibration sample.

[0048] In this embodiment, each effective local peak value can also be regarded as an effective energy band.

[0049] The specific implementation method of step S103 is as follows:

[0050] For each vibration sample, iterate through each value in the discrete spectrum sequence of that vibration sample. If a value satisfies either condition one or condition two below, then that value is determined to be a valid local peak in the discrete spectrum sequence:

[0051] Condition 1: This value is the maximum value in the discrete spectrum sequence;

[0052] Condition 2: The value is greater than or equal to its preceding value, and the value is greater than or equal to its following value, and the value is greater than or equal to five percent of the maximum value of the discrete spectrum sequence.

[0053] Condition two can be expressed by the following set of inequalities:

[0054]

[0055]

[0056]

[0057] Where V m，n，50 (k-1), V m，n，50 (k) and V m，n，50 (k+1) represents the (k-1), k, and k+1th values ​​in the discrete spectrum sequence, respectively, max(V m，n，50 ) represents the maximum value in a discrete spectral sequence.

[0058] For a vibration sample, by traversing each numerical point in the discrete spectrum sequence of the vibration sample according to the above conditions one and two, the numerical values ​​that satisfy either condition one or condition two can be selected. The one or more numerical values ​​obtained by selection are the effective local peaks of the vibration sample.

[0059] In some optional embodiments, to improve the accuracy of the method, the following steps may be performed before executing S103:

[0060] The discrete spectral sequence of each vibration sample is smoothed to obtain the smoothed discrete spectral sequence of each vibration sample.

[0061] In the above steps, the discrete spectral sequence can be processed using the Locally Scatterplot Smoothing (LOESS) algorithm. Specific implementation details of this algorithm can be found in existing technologies and will not be elaborated further. The smoothed discrete spectral sequence can be called a smoothed spectral sequence.

[0062] Optionally, other smoothing algorithms can also be used for smoothing, but this embodiment does not limit the application.

[0063] Understandably, if the above smoothing process is performed, the discrete spectrum sequence used in step S103 will be replaced with the smoothed discrete spectrum sequence. In other words, step S103 will then be:

[0064] For each vibration sample, identify each effective local peak in the smoothed discrete spectrum sequence of the vibration sample.

[0065] S104, For each vibration sample, calculate the energy concentration characteristics of the vibration sample based on the effective local peak value corresponding to the vibration sample.

[0066] The specific execution process of step S104 may include:

[0067] A1 determines the first effective local peak value of the vibration sample.

[0068] The first effective local peak is the effective local peak with the smallest corresponding frequency among the effective local peaks corresponding to the vibration sample. When the values ​​of the discrete spectrum sequence are traversed sequentially from low to high frequency in S103, the effective local peak first identified in a discrete spectrum sequence in S103 can also be directly determined as the first effective local peak of the discrete spectrum sequence.

[0069] In this embodiment, for the transformed vibration sample V m，n The first effective local peak in its discrete spectral sequence can be represented by p. m，n，1 express.

[0070] A2 sums up the squares of each effective local peak value corresponding to the vibration sample to obtain the total effective peak value of the vibration sample.

[0071] A3. Calculate the ratio of the square of the total effective peak value to the square of the first effective local peak value to obtain the energy concentration characteristics of the vibration sample.

[0072] Steps A2 and A3 above can be represented by the following formula (4):

[0073]

[0074] In formula (4), cnoc m，n Indicates v m，n The corresponding energy concentration characteristic, p m，n，i This represents the i-th effective local peak identified in the discrete spectrum sequence corresponding to the vibration sample, and Num represents the total number of effective local peaks identified in the discrete spectrum sequence corresponding to the vibration sample.

[0075] In some optional embodiments, in order to improve the efficiency of the method of this embodiment and complete the assessment of the degree of harmonic interference on the converter transformer more quickly, the following steps can be performed before executing S104:

[0076] Vibration samples with a number of effective local peaks less than or equal to a preset threshold are filtered out.

[0077] The number threshold can be set according to the actual situation. For example, the number threshold can be set to 3. That is, if the number of effective local peaks of a vibration sample is less than or equal to 3, the relevant data of the vibration sample, including the discrete spectrum sequence and effective local peaks of the vibration sample, will be removed and the vibration sample will not be analyzed in subsequent steps. If the number of effective local peaks of a vibration sample is greater than 3, the vibration sample, as well as the corresponding discrete spectrum sequence and effective local peaks, will be retained.

[0078] The reason for this is that when the number of effective local peaks is less than or equal to 3, it can be determined that the measurement point corresponding to the vibration sample is close to 0 in terms of harmonic interference during this sampling; while when the number of effective local peaks is greater than 3, it can be determined that the measurement point corresponding to the vibration sample may be affected by harmonic excitation sources, so it needs to be retained for analysis in subsequent steps.

[0079] The measurement point corresponding to the vibration sample can be understood as the installation position of the vibration sensor that collects the vibration sample on the casing of the converter transformer.

[0080] S105, For each vibration sample, calculate the energy distribution entropy characteristics of the vibration sample based on the effective local peak value and the frequency corresponding to the effective local peak value.

[0081] In step S105, the vibration sample v can first be calculated according to the following formula (5). m，n The weighted distribution probability prob of the corresponding i-th effective local peak m，n，i :

[0082]

[0083] In formula (5), w(f) m，n，i ) indicates based on vibration sample v m，n The frequency f corresponding to the i-th effective local peak m，n，i The weights are determined according to the following formula (6):

[0084]

[0085] Then, using the vibration sample v m，nThe corresponding weighted distribution probability prob of each effective local peak m，n，i Combining the following formula (7), the energy distribution entropy characteristic distEnt of the vibration sample is calculated. m，n :

[0086]

[0087] S106. Based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample, assess the degree of harmonic interference to the converter transformer at the current moment.

[0088] The specific execution process of step S106 may include:

[0089] B1. For each vibration sample, the degree of harmonic interference at the corresponding measuring point is determined based on the concentration interval to which the energy concentration characteristic of the vibration sample belongs and the distribution entropy interval to which the energy distribution entropy characteristic of the vibration sample belongs.

[0090] The measurement point corresponding to the vibration sample refers to the installation location of the vibration sensor used to collect the vibration sample.

[0091] In step B1, the criteria for determining the degree of harmonic interference at a measuring point can be represented by the following table 1:

[0092] Table 1

[0093] Number of effective local peaks Concentration range Distribution entropy interval Degree of harmonic interference Less than or equal to 3 Less than 1.1 Less than 0.5 No harmonic effects, meaning the impact is approximately 0%. Greater than 3 1.1 to 1.7 0.5 to 1.1 Mild harmonic interference, with an impact level of less than or equal to 10%. Greater than 3 Greater than 1.7 Greater than 1.1 Severe harmonic interference, with an impact level greater than 10%.

[0094] The judgment criteria in Table 1 indicate that for a vibration sample v m，n If the number of effective local peaks corresponding to the vibration sample is less than or equal to 3, or the energy concentration characteristic of the vibration sample is less than 1.1 and the energy distribution entropy characteristic is less than 0.5, then the measuring point corresponding to the vibration sample can be considered to have no harmonic influence, that is, the degree of influence on the measuring point when sampling the vibration sample is THD. m，n Approximately 0%.

[0095] If the number of effective local peaks corresponding to the vibration sample is greater than 3, the measuring point corresponding to the vibration sample is considered to be affected by harmonics. If the energy concentration characteristic of the vibration sample is in the range of 1.1 to 1.7, or the energy distribution entropy characteristic is in the range of 0.5 to 1.1, the measuring point corresponding to the vibration sample is considered to be slightly affected by harmonics, and the corresponding degree of influence is THD. m，n Less than or equal to 10%.

[0096] If the number of effective local peaks corresponding to the vibration sample is greater than 3, the measuring point corresponding to the vibration sample is considered to be affected by harmonics. If the energy concentration characteristic of the vibration sample is greater than 1.7, or the energy distribution entropy characteristic is greater than 1.1, the measuring point corresponding to the vibration sample is considered to be severely affected by harmonics, and the corresponding degree of influence is THD. m，n Greater than 10%.

[0097] B2. Determine the degree of harmonic interference on the converter transformer based on the degree of harmonic interference at the measurement points corresponding to each vibration sample.

[0098] In step B2, if it is determined that the number of measuring points with harmonic interference (including mild and severe harmonic interference as shown in Table 1) is less than 25% of the total number of measuring points, then the degree of harmonic interference on the converter transformer is considered to be: no harmonic interference.

[0099] If the number of measuring points affected by severe harmonics is greater than 80% of the total number of measuring points, then the degree of harmonic interference on the converter transformer is considered to be: severe harmonic interference.

[0100] If neither of the above two conditions is met, then the degree of harmonic interference to the converter transformer is considered to be: mild harmonic influence.

[0101] It should be noted that the degree of harmonic interference on the converter transformer determined in step B2 refers to the degree of harmonic interference when the current batch of vibration samples was obtained. As mentioned above, this embodiment can be executed periodically at certain time intervals. Each execution can obtain a batch of vibration samples through S101, and then analyze this batch of vibration samples using the above method to determine the degree of harmonic interference on the converter transformer during this sampling.

[0102] Based on the above technical solution, the present invention has the following beneficial technical effects:

[0103] The beneficial effects of this embodiment are as follows:

[0104] The present invention has no electrical connection with the transformer and does not require power outage of the transformer, thus having minimal impact on the operation of the entire power system.

[0105] The method of this invention is simple and easy to implement, and can accurately and effectively assess the degree of excitation source harmonic interference when it is impossible to measure the valve side voltage and current of the converter transformer in real time, so as to avoid misjudgment of the mechanical structure status of the converter transformer caused by excitation source harmonics.

[0106] To facilitate understanding of the technical solution of this application, the implementation process of this solution is illustrated below with a specific example.

[0107] In this example, a converter transformer can be controlled to operate under 0% harmonic, 10% harmonic, and 20% harmonic conditions respectively. Then, the method provided in this embodiment is executed under these three operating conditions to obtain the evaluation results corresponding to the three operating conditions.

[0108] During the evaluation, a highly sensitive vibration sensor must be selected to facilitate distortion-free acquisition of vibration signals. To ensure the sensor's vibration response within the sampling and filtering frequency band, the vibration sensor should be fixed to the side wall of the converter transformer tank, and should be attached using a magnetic base or adhesive. The vibration sampling device includes main modules such as preamplifier, anti-aliasing filter, and AD sampling. The AD sampling bit depth is at least 12 bits, and the anti-aliasing filter cutoff frequency is 3000Hz. When sampling vibration signals, the sampling frequency is at least 8000Hz. In this example, the sampling frequency for acquiring vibration signals is set to 8190Hz, the AD module sampling bit depth is 16 bits, and continuous sampling mode is used to record the entire experimental process.

[0109] Based on the above settings, after analyzing the vibration samples obtained by the vibration sensors at measuring points 1 and 2 using the method of the aforementioned embodiment, the following table 2 shows the vibration samples at different measuring points, the number of effective local peaks, energy concentration characteristics, and energy distribution entropy characteristics under different operating conditions.

[0110] Table 2

[0111] Based on the energy concentration characteristics and energy distribution entropy characteristics analyzed in Table 2, and combined with the judgment criteria in Table 1 above, the degree of harmonic interference obtained by measuring point 1 and measuring point 2 under different operating conditions, as shown in Table 3 below, can be determined according to different indicators (number of effective local peaks, energy concentration characteristics, and energy distribution entropy characteristics).

[0112] Table 3

[0113]

[0114] Combining this with step B2 above, which describes determining the overall harmonic interference level of the converter transformer based on the harmonic interference levels at multiple measuring points, it can be seen that under 0% harmonic operating conditions, the results from the aforementioned measuring points indicate that the converter transformer is not affected by harmonics; under 10% harmonic operating conditions, the results from the aforementioned measuring points indicate that the converter transformer is slightly affected by harmonics; and under 20% harmonic operating conditions, the results from the aforementioned measuring points indicate that the converter transformer is severely affected by harmonics. Therefore, the scheme in this embodiment has high accuracy.

[0115] According to the method for evaluating the degree of harmonic interference of the converter transformer excitation source using vibration signals provided in the embodiments of this application, the embodiments of this application also provide an apparatus for evaluating the degree of harmonic interference of the converter transformer excitation source using vibration signals. Please refer to [link to relevant documentation]. Figure 2 This is a schematic diagram of the structure of the device, which may include the following units.

[0116] The acquisition unit 201 is used to acquire multiple vibration samples of the converter transformer at the current moment; each vibration sample is a vibration signal acquired by a vibration sensor installed on the outer surface of the converter transformer.

[0117] The construction unit 202 is used to construct a discrete spectrum sequence of the vibration sample for each vibration sample by using the amplitude of the preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform.

[0118] The identification unit 203 is used to identify each effective local peak in the discrete spectrum sequence of each vibration sample.

[0119] Concentration calculation unit 204 is used to calculate the energy concentration characteristics of each vibration sample based on the effective local peak value corresponding to the vibration sample.

[0120] The distribution entropy calculation unit 205 is used to calculate the energy distribution entropy characteristics of each vibration sample based on the effective local peak value and the frequency corresponding to the effective local peak value.

[0121] Evaluation unit 206 is used to evaluate the degree of harmonic interference to the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample.

[0122] Optionally, the identification unit 203 is also used for:

[0123] The discrete spectrum sequence of each vibration sample is smoothed to obtain the smoothed discrete spectrum sequence of each vibration sample.

[0124] For each vibration sample, when identifying each effective local peak in the discrete spectrum sequence of the vibration sample, the identification unit 203 is specifically used for:

[0125] For each vibration sample, identify each effective local peak in the smoothed discrete spectrum sequence of the vibration sample.

[0126] Optionally, the identification unit 203 is also used for:

[0127] Vibration samples with a number of effective local peaks less than or equal to a preset threshold are filtered out.

[0128] Optionally, when the concentration calculation unit 204 calculates the energy concentration characteristics of the vibration sample based on the effective local peak value corresponding to the vibration sample, it is specifically used for:

[0129] Determine the first effective local peak value of the vibration sample; wherein, the first effective local peak value is the effective local peak value with the smallest corresponding frequency among the effective local peak values ​​of the vibration sample;

[0130] The total effective peak value of the vibration sample is obtained by summing the squares of each effective local peak value corresponding to the vibration sample.

[0131] The energy concentration characteristics of the vibration sample are obtained by calculating the ratio of the total effective peak value to the square of the first effective local peak value.

[0132] Optionally, when evaluating the degree of harmonic interference to the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample, the evaluation unit 206 is specifically used for:

[0133] For each vibration sample, the degree of harmonic interference at the corresponding measuring point is determined based on the concentration interval to which the energy concentration characteristic of the vibration sample belongs and the distribution entropy interval to which the energy distribution entropy characteristic of the vibration sample belongs; where the measuring point corresponding to the vibration sample refers to the installation location of the vibration sensor that collects the vibration sample.

[0134] The degree of harmonic interference on the converter transformer is determined based on the degree of harmonic interference at the measuring points corresponding to each vibration sample.

[0135] The device for evaluating the degree of harmonic interference of the excitation source of a converter transformer using vibration signals provided in this embodiment can be found in the relevant steps and beneficial effects of the method for evaluating the degree of harmonic interference of the excitation source of a converter transformer using vibration signals provided in this application embodiment, and will not be repeated here.

[0136] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0137] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0138] Those skilled in the art will be able to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for assessing the degree of harmonic interference from the excitation source of a converter transformer using vibration signals, characterized in that, include: Multiple vibration samples of the converter transformer at the current moment are collected; wherein each vibration sample is a vibration signal collected by a vibration sensor installed on the outer surface of the converter transformer. For each vibration sample, a discrete spectrum sequence of the vibration sample is constructed using the amplitude of a preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform. For each vibration sample, identify each effective local peak in the discrete spectral sequence of the vibration sample; For each vibration sample, the energy concentration characteristic of the vibration sample is calculated based on the effective local peak value corresponding to the vibration sample. For each vibration sample, the energy distribution entropy feature of the vibration sample is calculated based on the effective local peak value and the frequency corresponding to the effective local peak value. This includes: calculating the weight of each effective local peak value based on the frequency corresponding to each effective local peak value; for each effective local peak value, multiplying the square of the effective local peak value by the corresponding weight to obtain a first calculation result; multiplying the squares of all effective local peak values ​​by their respective weights and summing them to obtain a second calculation result; using the ratio of the first calculation result to the second calculation result as the weight distribution probability of the effective local peak value; and calculating the energy distribution entropy based on the weight distribution probability. Based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample, assess the degree of harmonic interference affecting the converter transformer at the current moment; The step of calculating the energy concentration characteristics of the vibration sample based on the effective local peak value corresponding to the vibration sample includes: Determine the first effective local peak value of the vibration sample; wherein, the first effective local peak value is the effective local peak value with the smallest corresponding frequency among the effective local peak values ​​corresponding to the vibration sample; The total effective peak value of the vibration sample is obtained by summing the squares of each effective local peak value corresponding to the vibration sample. The energy concentration characteristics of the vibration sample are obtained by calculating the ratio of the total effective peak value to the square of the first effective local peak value.

2. The method according to claim 1, characterized in that, Before identifying each effective local peak in the discrete spectral sequence of each vibration sample, the method further includes: The discrete spectrum sequence of each vibration sample is smoothed to obtain the smoothed discrete spectrum sequence of each vibration sample. The step of identifying each effective local peak in the discrete spectral sequence of each vibration sample includes: For each vibration sample, identify each effective local peak in the smoothed discrete spectral sequence of the vibration sample.

3. The method according to claim 1, characterized in that, Before calculating the energy concentration characteristics of each vibration sample based on the effective local peak value corresponding to the vibration sample, the method further includes: Vibration samples whose number of effective local peaks is less than or equal to a preset threshold are filtered out.

4. The method according to claim 1, characterized in that, The assessment of the harmonic interference level of the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample includes: For each vibration sample, the degree of harmonic interference at the corresponding measuring point is determined based on the concentration interval to which the energy concentration characteristic of the vibration sample belongs and the distribution entropy interval to which the energy distribution entropy characteristic of the vibration sample belongs; wherein, the measuring point corresponding to the vibration sample refers to the installation location of the vibration sensor that collects the vibration sample. The degree of harmonic interference on the converter transformer is determined based on the degree of harmonic interference at the measuring points corresponding to each vibration sample.

5. A device for assessing the degree of harmonic interference from a converter transformer excitation source using vibration signals, characterized in that, include: The acquisition unit is used to acquire multiple vibration samples of the converter transformer at the current moment; wherein each vibration sample is a vibration signal acquired by a vibration sensor installed on the outer surface of the converter transformer. The construction unit is used to construct a discrete spectrum sequence of each vibration sample by using the amplitude of a preset reference frequency and the amplitude of the harmonics of the reference frequency in the vibration sample after Fourier transform. The identification unit is used to identify each effective local peak in the discrete spectrum sequence of each vibration sample. A concentration calculation unit is used to calculate the energy concentration characteristics of each vibration sample based on the effective local peak value corresponding to the vibration sample. The distribution entropy calculation unit is used to calculate the energy distribution entropy characteristics of each vibration sample based on the effective local peak value and the frequency corresponding to the effective local peak value. This includes: calculating the weight of each effective local peak value based on the frequency corresponding to each effective local peak value; for each effective local peak value, multiplying the square of the effective local peak value by its corresponding weight to obtain a first calculation result; multiplying the squares of all effective local peak values ​​by their respective weights and summing them to obtain a second calculation result; using the ratio of the first calculation result to the second calculation result as the weighted distribution probability of the effective local peak value; and calculating the energy distribution entropy based on the weighted distribution probability. The evaluation unit is used to evaluate the degree of harmonic interference of the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample. When the concentration calculation unit calculates the energy concentration characteristics of the vibration sample based on the effective local peak value corresponding to the vibration sample, it is specifically used for: Determine the first effective local peak value of the vibration sample; wherein, the first effective local peak value is the effective local peak value with the smallest corresponding frequency among the effective local peak values ​​corresponding to the vibration sample; The total effective peak value of the vibration sample is obtained by summing the squares of each effective local peak value corresponding to the vibration sample. The energy concentration characteristics of the vibration sample are obtained by calculating the ratio of the total effective peak value to the square of the first effective local peak value.

6. The apparatus according to claim 5, characterized in that, The identification unit is also used for: The discrete spectrum sequence of each vibration sample is smoothed to obtain the smoothed discrete spectrum sequence of each vibration sample. When the identification unit identifies each effective local peak in the discrete spectral sequence of each vibration sample, it is specifically used for: For each vibration sample, identify each effective local peak in the smoothed discrete spectral sequence of the vibration sample.

7. The apparatus according to claim 5, characterized in that, The identification unit is also used for: Vibration samples whose number of effective local peaks is less than or equal to a preset threshold are filtered out.

8. The apparatus according to claim 5, characterized in that, When the evaluation unit assesses the degree of harmonic interference to the converter transformer at the current moment based on the energy concentration characteristics and energy distribution entropy characteristics of each vibration sample, it is specifically used for: For each vibration sample, the degree of harmonic interference at the corresponding measuring point is determined based on the concentration interval to which the energy concentration characteristic of the vibration sample belongs and the distribution entropy interval to which the energy distribution entropy characteristic of the vibration sample belongs; wherein, the measuring point corresponding to the vibration sample refers to the installation location of the vibration sensor that collects the vibration sample. The degree of harmonic interference on the converter transformer is determined based on the degree of harmonic interference at the measuring points corresponding to each vibration sample.

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