A substation resonant frequency identification method and device based on multi-sampling rate data fusion

Abstract

The application provides a substation resonance frequency identification method and device based on multi-sampling rate data fusion, and relates to the field of resonance frequency identification of new power systems. The method comprises the following steps: synchronously acquiring time-domain recording data of a first measuring point and a second measuring point of a substation to be identified, determining a first frequency and a second frequency with abnormal harmonic content, the first measuring point and the second measuring point being adjacent measuring points of the substation to be identified, and the time-domain recording data comprising voltage and current; determining a preliminary real frequency and a preliminary distorted frequency according to the first frequency and the second frequency, the preliminary distorted frequency being a frequency mixed with the preliminary real frequency into a low frequency; constructing an equivalent impedance model of the substation to be identified, and determining a third frequency with abnormal harmonic content based on the equivalent impedance model; and identifying the harmonic abnormal frequency of the substation to be identified based on the third frequency, the preliminary real frequency and the preliminary distorted frequency. The application can improve the accuracy and reliability of resonance frequency identification under the condition of multi-sampling rate monitoring.

Description

Technical Field

[0001] This application relates to the field of resonant frequency identification in novel power systems, and in particular to a method and apparatus for identifying the resonant frequency of a substation by multi-sampling rate data fusion. Background Technology

[0002] With the gradual advancement of the construction of new power systems, the proportion of new energy power generation and power electronic equipment is increasing, leading to a gradual increase in the types and numbers of harmonic pollution sources in the power grid, and frequent harmonic resonance phenomena. The large-scale integration of voltage source converters, frequency converters, and other power electronic power conversion equipment significantly increases the emission level of high-frequency harmonics due to their high switching frequencies and strong nonlinearities. These high-frequency harmonics may be amplified resonantly during their transmission through the power grid due to inductive and capacitive impedance parameter mismatch, seriously threatening the safe and stable operation of the new power system.

[0003] Currently, the main devices used for harmonic monitoring in substations include fault recording devices and online power quality monitoring devices. Fault recording devices typically have a sampling rate below 10kHz, while online power quality monitoring devices generally have sampling rates of 12.8kHz, 25.6kHz, or even higher. Due to this inconsistency in sampling rates, harmonic spectrum analysis results obtained from different monitoring devices within the same system differ, making it difficult to identify the actual resonant frequencies and severely impacting resonance source tracing and harmonic mitigation. Therefore, how to accurately identify the actual resonant frequencies in the power grid using multi-sampling-rate data fusion analysis, given the different sampling rates of harmonic monitoring devices and the inconsistent harmonic spectrum analysis results, is a critical technical challenge that urgently needs to be addressed. Summary of the Invention

[0004] This application provides a method and device for identifying the resonant frequency of a substation by fusing data from multiple sampling rates, in order to solve the problem that the different sampling rates of existing substation harmonic monitoring devices lead to differences in harmonic spectrum analysis results, which in turn makes it difficult to accurately identify the resonant frequency.

[0005] Firstly, this application provides a method for identifying the resonant frequency of a substation using multi-sampling-rate data fusion, including: The time-domain waveform data of the first and second measuring points of the substation to be identified are acquired simultaneously to determine the first and second frequencies of abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified. The time-domain waveform data includes voltage and current. Based on the first frequency and the second frequency, a preliminary true frequency and a preliminary distortion frequency are determined, wherein the preliminary distortion frequency is a frequency that is superimposed on the preliminary true frequency to a lower frequency. Construct an equivalent impedance model of the substation to be identified, and determine the third frequency of abnormal harmonic content based on the equivalent impedance model; Based on the third frequency, the preliminary true frequency, and the preliminary distorted frequency, the harmonic abnormal frequency of the substation to be identified is determined.

[0006] Secondly, this application provides a substation resonant frequency identification device based on multi-sampling rate data fusion, comprising: The frequency determination module is used to synchronously acquire time-domain waveform data of the first and second measuring points of the substation to be identified, and determine the first and second frequencies with abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified. The time-domain waveform data includes voltage and current. The preliminary judgment module is used to determine a preliminary true frequency and a preliminary distortion frequency based on the first frequency and the second frequency, wherein the preliminary distortion frequency is a frequency that is superimposed on the preliminary true frequency to a low frequency. The frequency calculation module is used to construct the equivalent impedance model of the substation to be identified, and based on the equivalent impedance model, determine the third frequency of abnormal harmonic content. The frequency identification module is used to identify the harmonic abnormal frequency of the substation to be identified based on the third frequency, the preliminary true frequency, and the preliminary distorted frequency.

[0007] This application provides a method and device for identifying the resonant frequency of a substation using multi-sampling-rate data fusion. By synchronously collecting voltage and current data from different measuring points within the same system, it analyzes the preliminary true frequency and preliminary distorted frequency of abnormal harmonic content. Combined with an equivalent impedance model established using grid parameters, it further verifies the true frequency of abnormal harmonic content using harmonic impedance characteristics and harmonic transitivity. This solves the problem of difficulty in identifying the resonant frequency due to differences in the sampling rates of monitoring devices. Simultaneously, by utilizing multi-sampling-rate harmonic monitoring data and grid parameters, it achieves accurate identification of the true resonant frequency of the substation, resolving the issues of inconsistent harmonic spectrum analysis results and unclear true resonant frequencies caused by differences in the sampling rates of monitoring devices. This effectively improves the accuracy and reliability of resonant frequency identification under multi-sampling-rate monitoring conditions, providing technical support for high-frequency resonance monitoring and tracing in new power systems. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application, 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1This is a flowchart illustrating the implementation of the substation resonant frequency identification method based on multi-sampling-rate data fusion provided in this application embodiment; Figure 2 This is a schematic diagram of the equivalent impedance model provided in the embodiments of this application; Figure 3 This is a schematic diagram showing the locations of voltage and current sampling points provided in an embodiment of this application; Figure 4 This is a schematic diagram of the voltage and outgoing current spectrum of the 110kV side bus of the transformer provided in the embodiments of this application; Figure 5 This is a schematic diagram of the bus voltage and total incoming current spectrum of a 110kV substation provided in an embodiment of this application; Figure 6 This is an equivalent impedance diagram provided in the embodiments of this application, showing the impedance from the neutral point N of the 220kV substation transformer to the 220kV side and the 110kV side. Figure 7 This is the equivalent impedance diagram from the neutral point N of the 220kV substation transformer to the SVG reactor side of the 35kV system, provided in the embodiments of this application; Figure 8 This is an equivalent impedance diagram from the 35kV SVG generator side to the 220kV and 110kV systems provided in the embodiments of this application; Figure 9 This is a diagram showing the amplification factor of the high-frequency disturbance voltage transmitted from the 35kV SVG generator side to the 35kV transformer side, provided in an embodiment of this application. Figure 10 This is a diagram showing the amplification factor of the high-frequency disturbance voltage transmitted from the 35kV SVG generator side to the 220kV transformer side, provided in an embodiment of this application. Figure 11 This is a diagram showing the amplification factor of the high-frequency disturbance voltage transmitted from the 35kV SVG generator side to the 110kV transformer side, provided in an embodiment of this application. Figure 12 This is a diagram showing the amplification factor of the high-frequency disturbance voltage transmitted from the 35kV SVG machine side to the 110kV side of the wind farm, provided in an embodiment of this application. Figure 13 This is a schematic diagram of the substation resonant frequency identification device for multi-sampling rate data fusion provided in the embodiments of this application. Detailed Implementation

[0010] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0011] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0012] Figure 1 The implementation flowchart of the substation resonant frequency identification method based on multi-sampling rate data fusion provided in the embodiments of this application is described in detail below: In step 101, time-domain waveform data of the first and second measuring points of the substation to be identified are acquired synchronously to determine the first and second frequencies of abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified, and the time-domain waveform data includes voltage and current.

[0013] In this embodiment, time-domain waveform data containing voltage and current are collected from a first measuring point of the substation to be identified, and simultaneously, time-domain waveform data containing voltage and current are collected from a second measuring point adjacent to the first measuring point of the substation. Then, time-frequency transformation technology is used to analyze the time-domain waveform data of the first measuring point to obtain a first frequency with abnormal harmonic content, and to analyze the time-domain waveform data of the second measuring point to obtain a second frequency with abnormal harmonic content. The time-frequency transformation technology can be a discrete Fourier transform.

[0014] This application embodiment simultaneously acquires time-domain waveform data from adjacent first and second measurement points of the substation to be identified. By comprehensively analyzing the data from two different locations, the electrical signal characteristics within the substation can be captured more comprehensively. Data from different measurement points can complement and verify each other, avoiding the errors and limitations that may exist with data from a single measurement point. This effectively improves the accuracy of detecting abnormal frequencies with harmonic content, laying the foundation for accurate identification of resonant frequencies in the future.

[0015] In one possible implementation, synchronously acquiring time-domain waveform data from the first and second measuring points of the substation to be identified, and determining the first and second frequencies of abnormal harmonic content, may include: The first time-domain waveform data of the first measurement point of the substation to be identified is acquired, and the first time-domain waveform data is converted into first frequency-domain data through discrete Fourier transform. The first time-domain waveform data includes the first voltage and the first current. The second time-domain waveform data of the second measuring point of the substation to be identified is acquired synchronously, and the second time-domain waveform data is converted into second frequency-domain data through discrete Fourier transform. The second time-domain waveform data includes the second voltage and the second current. Based on the first frequency domain data, determine the first frequency of the abnormal harmonic content; Based on the second frequency domain data, the second frequency with abnormal harmonic content was determined.

[0016] Optionally, the first measuring point of the substation to be identified, including the first voltage, is collected. and the first current The first time-domain waveform data is simultaneously acquired, along with the second voltage data from the second measuring point adjacent to the first measuring point in the substation to be identified. Second current The second time-domain waveform data is then processed using a discrete Fourier transform to convert the sampled signal (i.e., the first voltage) into a waveform. First current Second voltage Second current If we convert the time-domain representation to the frequency-domain representation and set the window width to 10 cycles, then: Input the first time-domain waveform data into the first formula to obtain the first frequency-domain data. The first formula is:

[0017]

[0018] in, The first measuring point of the substation to be identified Root mean square value of second harmonic voltage The first voltage, This represents the number of sampling points for 10 cycles of a discrete-time signal of a voltage or current waveform. The number of the discrete-time signal, with a value range of . ; For harmonic order, The first measuring point of the substation to be identified Root mean square value of second harmonic current For the first current, The imaginary unit, To obtain the modulus of the phasor, It is a natural constant.

[0019] That is, the first measuring point containing the substation to be identified is obtained. RMS value of second harmonic voltage and the first measuring point of the substation to be identified RMS value of second harmonic current The first frequency domain data.

[0020] Then, based on the first frequency domain data, the harmonic frequency of the first measuring point in the substation to be identified with abnormal harmonic content is selected as the first frequency. .

[0021] Input the second time-domain waveform data into the eighth formula to obtain the second frequency-domain data. The eighth formula is:

[0022]

[0023] in, The second measuring point of the substation to be identified Root mean square value of second harmonic voltage For the second voltage, The second measuring point of the substation to be identified Root mean square value of second harmonic current This is the second current.

[0024] That is, the second measuring point containing the substation to be identified is obtained. RMS value of second harmonic voltage and the second measuring point of the substation to be identified RMS value of second harmonic current The first frequency domain data.

[0025] Then, based on the second frequency domain data, the harmonic frequency of the abnormal harmonic content at the second measuring point of the substation to be identified is selected as the second frequency. .

[0026] In step 102, a preliminary true frequency and a preliminary distortion frequency are determined based on a first frequency and a second frequency. The preliminary distortion frequency is the frequency that is superimposed on the preliminary true frequency to a lower frequency.

[0027] In this embodiment of the application, after determining the first frequency and the second frequency, the principle of spectral aliasing is used to preliminarily determine which of the first frequency and the second frequency is the true frequency with abnormal harmonic content (i.e., the preliminary true frequency) and which is the distorted frequency that is aliased to the lower frequency with the true frequency (i.e., the preliminary distorted frequency).

[0028] This application first determines the first and second frequencies with abnormal harmonic content, and then further determines the preliminary true frequency and the preliminary distorted frequency. This multi-step frequency analysis method gradually and deeply mines the frequency information in the data, which can more accurately distinguish between the true frequency and the distorted frequency caused by aliasing and other reasons, reduce the possibility of misjudgment, and improve the accuracy of the preliminary frequency determination.

[0029] In one possible implementation, determining the preliminary true frequency and the preliminary distortion frequency based on the first frequency and the second frequency may include: Determine whether the first frequency is less than the second frequency; If the first frequency is less than the second frequency, then the preliminary true frequency and the preliminary distortion frequency are determined based on the first frequency and the second frequency.

[0030] Optionally, determine the first frequency. Is it less than the second frequency? ,like According to the principle of spectral aliasing, the first frequency... Second frequency Enter it into the second formula, where the second formula is:

[0031] in, For the first frequency, For the second frequency, It is a minimum value function. The sampling frequency of the first measurement point is... For integer variables, It is an integer. It is an absolute value function.

[0032] Determine whether the second formula above is true. If it is true, then set the second frequency... The frequency identified as a genuine harmonic anomaly in the system, i.e., the preliminary true frequency, is then set as the first frequency. The frequency identified as the initial distortion frequency is due to aliasing to lower frequencies caused by insufficient sampling rate of the harmonic monitoring device. If this is not the case, then the first frequency is... The frequency was determined to be the initial true frequency, and the second frequency was... The frequency was determined to be a preliminary distortion frequency.

[0033] like According to the principle of spectral aliasing, the first frequency... Second frequency Enter it into the ninth formula, where the ninth formula is:

[0034] in, The sampling frequency is the sampling frequency of the second measurement point.

[0035] Determine whether the above ninth formula is true. If it is true, then set the first frequency... The frequency was determined to be the initial true frequency, and the second frequency was... The frequency is determined to be the initial distortion frequency. If this is not the case, then the second frequency is determined. This was determined to be the preliminary true frequency, and the first frequency was... The frequency was determined to be a preliminary distortion frequency.

[0036] In step 103, an equivalent impedance model of the substation to be identified is constructed, and based on the equivalent impedance model, the third frequency of the abnormal harmonic content is determined.

[0037] In this embodiment of the application, parameters such as transformers and lines of the substation to be identified are collected, an equivalent impedance model of the substation to be identified is constructed, harmonic impedance characteristics and harmonic transmission characteristics are analyzed, and a third frequency with abnormal harmonic content is obtained.

[0038] This application constructs an equivalent impedance model of the substation to be identified and determines the third frequency with abnormal harmonic content based on the model. The equivalent impedance model can reflect the electrical characteristics of the substation. Analyzing the substation using this model can provide a deeper understanding of the generation and propagation mechanisms of harmonics within the substation, providing a more accurate basis for frequency identification at the system level, and further improving the accuracy of identifying the target true frequency and the target distorted frequency.

[0039] In one possible implementation, constructing the equivalent impedance model of the substation to be identified can include: Collect the physical parameters of the substation to be identified, including transformer impedance voltage, transformer medium-voltage side rated voltage, transformer medium-voltage side rated capacity, and system short-circuit capacity. Using physical parameters, construct an equivalent impedance model.

[0040] Optionally, physical parameters of the substation to be identified, including transformer impedance voltage, are collected. Rated voltage on the medium-voltage side of the transformer Rated capacity of the medium-voltage side of the transformer and system short-circuit capacity The following calculations are all converted to the medium-voltage side of the transformer to construct the equivalent impedance model of the substation to be identified, such as... Figure 2 As shown, the specific calculation formula is as follows:

[0041]

[0042]

[0043]

[0044]

[0045] in, The transformer is equivalent to the system fundamental impedance at a higher system level. This is the rated voltage on the medium-voltage side of the transformer. For system short-circuit capacity, For transformers to higher systems Second equivalent harmonic impedance This refers to the fundamental short-circuit impedance on the high-voltage side of the transformer. This is the impedance voltage on the high-voltage side of the transformer. This refers to the rated capacity of the medium-voltage side of the transformer. This refers to the fundamental short-circuit impedance on the medium-voltage side of the transformer. This is the impedance voltage on the medium-voltage side of the transformer. This refers to the fundamental short-circuit impedance on the low-voltage side of the transformer. This is the impedance voltage on the low-voltage side of the transformer.

[0046] In one possible implementation, determining the third frequency of the harmonic content anomaly based on the equivalent impedance model can include: Based on the equivalent impedance model, the target equivalent harmonic impedance and the target harmonic voltage transfer coefficient are calculated. The target equivalent harmonic impedance is the impedance from the low-voltage load side of the transformer to the high- and medium-voltage sides of the transformer. The equivalent harmonic impedance and the target harmonic voltage transfer coefficient are derived from the low-voltage load side of the transformer to the high, medium, and low-voltage busbars of the transformer, as well as the medium-voltage substation busbar. Subharmonic voltage transfer coefficient; When the amplitude of the target equivalent harmonic impedance is at its minimum and the target harmonic voltage transfer coefficient is at its maximum, the target harmonic frequency in which the harmonic anomaly occurs is determined. The third frequency is calculated using the target harmonic frequency.

[0047] Optionally, the target equivalent harmonic impedance and target harmonic voltage transfer coefficient are calculated based on the constructed equivalent impedance model of the substation to be identified.

[0048] The calculation of the target equivalent harmonic impedance may include: Based on the equivalent impedance model, the first equivalent harmonic impedance, the second equivalent harmonic impedance, and the third equivalent harmonic impedance are calculated respectively. The first equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer high-voltage side. The second equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer medium-voltage side. The second equivalent harmonic impedance and the third equivalent harmonic impedance are the impedance from the transformer neutral point to the low-voltage side of the transformer. The formula for calculating the second equivalent harmonic impedance is:

[0049]

[0050]

[0051] in, The first equivalent harmonic impedance, The second equivalent harmonic impedance, The third equivalent harmonic impedance, From the medium-voltage side busbar of the transformer to the medium-voltage side substation Secondary equivalent load impedance For the low-voltage side of the transformer Secondary equivalent load impedance.

[0052] If the first equivalent harmonic impedance Second equivalent harmonic impedance and third equivalent harmonic impedance If the input impedance angle sign is different, then the first equivalent harmonic impedance will be... Second equivalent harmonic impedance and third equivalent harmonic impedance The input is given to the third formula to calculate the target equivalent harmonic impedance. The third formula is:

[0053] in, For the target equivalent harmonic impedance, The first equivalent harmonic impedance, The second equivalent harmonic impedance, The third equivalent harmonic impedance, This is the impedance parallel operator.

[0054] In addition, the target harmonic voltage transfer coefficient includes the first harmonic voltage transfer coefficient. Second harmonic voltage transfer coefficient Third harmonic voltage transfer coefficient and the fourth harmonic voltage transfer coefficient Among them, the first harmonic voltage transfer coefficient For transmission from the low-load side of the transformer to the high-voltage busbar of the transformer Second harmonic voltage transfer coefficient, second harmonic voltage transfer coefficient To transmit voltage from the low-load side of the transformer to the medium-voltage side busbar of the transformer. Second harmonic voltage transfer coefficient, third harmonic voltage transfer coefficient For transmission from the low-load side of the transformer to the low-voltage side busbar of the transformer Second harmonic voltage transfer coefficient, fourth harmonic voltage transfer coefficient To transmit power from the low-load side of the transformer to the medium-voltage side of the substation busbar Subharmonic voltage transfer coefficient.

[0055] Accordingly, the target harmonic voltage transfer coefficient is calculated, including: The first harmonic voltage transfer coefficient is calculated using the fourth formula, which is:

[0056] in, The first harmonic voltage transfer coefficient, For transformers to higher systems Subequivalent harmonic impedance; The second harmonic voltage transfer coefficient is calculated using the fifth formula, which is:

[0057] in, The second harmonic voltage transfer coefficient, For medium-voltage side substations Secondary equivalent load impedance From the medium-voltage side busbar of the transformer to the medium-voltage side substation Secondary equivalent load impedance; The third harmonic voltage transfer coefficient is calculated using the sixth formula, which is:

[0058] in, The third harmonic voltage transfer coefficient. For harmonic order, This refers to the fundamental short-circuit impedance on the low-voltage side of the transformer. The imaginary unit; The fourth harmonic voltage transfer coefficient is calculated using the seventh formula, which is:

[0059] in, This is the fourth harmonic voltage transfer coefficient.

[0060] Then, when the harmonic order is At this time, the target equivalent harmonic impedance The amplitude reaches an extreme value (i.e., a minimum value), and the harmonic impedance angle crosses from -90° to 90° (or from 90° to -90°), that is, when At that time, the target equivalent harmonic impedance It is soluble; when At that time, the target equivalent harmonic impedance Presented as sensual (or when) At that time, the target equivalent harmonic impedance Presented with emotion; when At that time, the target equivalent harmonic impedance (Capacitive). And the target harmonic voltage transfer coefficient (i.e. , , , The presence of a maximum value indicates the existence of resonance at this frequency, which is the target harmonic frequency at which the system exhibits harmonic anomalies. Then the third frequency is:

[0061] in, It is the third frequency.

[0062] In step 104, the harmonic abnormal frequency of the substation to be identified is determined based on the third frequency, the preliminary true frequency, and the preliminary distorted frequency.

[0063] In this embodiment of the application, the calculated third frequency is compared with the preliminary true frequency selected from the first frequency and the second frequency in step 102. If the third frequency is equal to the preliminary true frequency, it can be verified that the preliminary true frequency selected in step 102 is the target true frequency, and the preliminary distortion frequency is the true target distortion frequency.

[0064] For example, if the second frequency is the initial true frequency, then if the third frequency is equal to the second frequency, it can be verified that the second frequency is the actual harmonic abnormal frequency of the system. The first frequency is due to insufficient sampling rate of the waveform recording device, and the second frequency is aliased to a low frequency, which is caused by measurement distortion.

[0065] This application's embodiments accurately identify abnormal harmonic frequencies in substations, enabling operators to promptly understand the generation and propagation of harmonics within the substation. Harmonics are a significant factor affecting the safe and stable operation of substations; excessive harmonics can lead to equipment overheating, insulation aging, malfunctions, and even system failures. By promptly detecting harmonic anomalies using this method, operators can take targeted measures, such as adjusting system parameters and activating filtering devices, to effectively suppress harmonics and ensure the normal operation of the substation.

[0066] Based on the method provided in this application, the following embodiments will be used to illustrate the method: A simplified topology of a 220kV substation is as follows: Figure 3 As shown, the waveform data of the bus voltage and outgoing current on the 110kV side of the transformer were collected, and the sampling frequency was... The frequency is 1600Hz; simultaneously, waveform data of the 110kV bus voltage and total incoming current of adjacent 110kV substations are collected, with a sampling frequency of 1600Hz. The frequency is 12800Hz. Time-frequency transformation technology was used to analyze the above recorded waveform data to obtain the harmonic voltage and harmonic current content of each frequency, such as... Figure 4 , Figure 5 As shown, the abnormal harmonic frequencies are 3.4 and 60.6, respectively, which are the first frequencies. 170Hz, second frequency It is 3030Hz.

[0067] Sampling frequency of the waveform recording device 1600Hz, 32 sampling points per cycle, first frequency At 170Hz, according to the Nyquist sampling theorem, the presence of harmonics above 800Hz (16th order) can cause spectral aliasing. Harmonic components above the 16th order will alias into spectral components below the 16th order. Based on the principle of spectral aliasing, we can conclude that:

[0068] The second frequency is obtained from the above formula. The first frequency is the actual harmonic anomaly frequency (i.e., the preliminary true frequency) that exists in the system. The second frequency is due to insufficient sampling rate of the waveform recording device. The initial distortion frequency of aliasing to low frequencies.

[0069] The main transformer of the 220kV substation has a rated voltage of 220kV / 110kV / 35kV, a rated capacity of 200MVA, a system short-circuit capacity of 12000MVA, and a short-circuit voltage between the high-voltage and intermediate-voltage windings. Short-circuit voltage between medium and low voltage side windings Short-circuit voltage between low and high voltage side windings The three windings are connected in a YY-Δ configuration. The two Static Var Generators (SVG) on the 35kV side of the 220kV substation main transformer have rated capacities of 40Mvar each. The single-phase rated capacity of the reactor is 1067kvar, the rated current is 659.8A, and the rated impedance is 2.451A. .

[0070] Calculate the equivalent impedance from the neutral point N of the 220kV substation transformer to the 220kV side and the 110kV side. The calculation results are as follows: Figure 6 As shown, the parallel equivalent impedance exhibits capacitive behavior in the 60.6th harmonic.

[0071] Calculate the equivalent impedance from the neutral point N of the 220kV substation transformer to the SVG reactor side of the 35kV system. The calculation results are as follows: Figure 7 As shown, the equivalent impedance exhibits inductive behavior in the 60.6th harmonic.

[0072] Calculate the equivalent impedance from the SVG generator side of the 35kV system to 220kV and 110kV. The calculation results are as follows: Figure 8 As shown, the phase frequency characteristic of the equivalent impedance has a crossing from -90° to 90° in the 60.6th harmonic, indicating that there is a series resonance at this frequency.

[0073] Calculate the high-frequency disturbance voltage amplification factors transmitted from the SVG generator side of the 35kV system to the main transformer at 35kV, 220kV, and 110kV, and to the 110kV side of the wind farm. Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown, the amplification factors are 185.842, 18.6819, 355.396, and 383.234, indicating that the 60.6th order high-frequency disturbance voltage from the SVG AC output side is amplified by series resonance when transmitted to the 110kV system. This means the harmonic order of the third frequency of the harmonic anomaly is 60.6 (3030Hz). It can be further determined that the second frequency of 3030Hz is the true frequency of the harmonic anomaly, and the first frequency of 170Hz is the distorted frequency resulting from the aliasing of this true frequency of 3030Hz to lower frequencies.

[0074] This application provides a substation resonant frequency identification method based on multi-sampling rate data fusion. By synchronously collecting voltage and current data from different measuring points within the same system, it analyzes the preliminary true frequency and preliminary distorted frequency of abnormal harmonic content. Combined with an equivalent impedance model established using grid parameters, it further verifies the true frequency of abnormal harmonic content using harmonic impedance characteristics and harmonic transitivity, thus solving the problem of difficulty in identifying resonant frequencies due to differences in the sampling rates of monitoring devices. Simultaneously, by utilizing multi-sampling rate harmonic monitoring data and grid parameters, it achieves accurate identification of the true resonant frequency of the substation, resolving the issues of inconsistent harmonic spectrum analysis results and unclear true resonant frequencies caused by differences in the sampling rates of monitoring devices. This effectively improves the accuracy and reliability of resonant frequency identification under multi-sampling rate monitoring conditions, providing technical support for high-frequency resonance monitoring and tracing in new power systems.

[0075] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0076] The following are device embodiments of this application. For details not described in detail, please refer to the corresponding method embodiments described above.

[0077] Figure 13 A schematic diagram of the substation resonant frequency identification device based on multi-sampling rate data fusion provided in this application embodiment is shown. For ease of explanation, only the parts relevant to this application embodiment are shown, and are described in detail below: like Figure 13 As shown, the substation resonant frequency identification device 13, which integrates multi-sampling rate data fusion, includes: The frequency determination module 131 is used to synchronously acquire the time-domain waveform data of the first and second measuring points of the substation to be identified, and determine the first and second frequencies with abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified. The time-domain waveform data includes voltage and current. The preliminary judgment module 132 is used to determine the preliminary true frequency and the preliminary distortion frequency based on the first frequency and the second frequency. The preliminary distortion frequency is the frequency that is superimposed on the preliminary true frequency to a lower frequency. The frequency calculation module 133 is used to construct the equivalent impedance model of the substation to be identified, and to determine the third frequency of the abnormal harmonic content based on the equivalent impedance model. The frequency identification module 134 is used to identify the harmonic abnormal frequency of the substation to be identified based on the third frequency, the preliminary true frequency and the preliminary distorted frequency.

[0078] This application provides a substation resonant frequency identification device based on multi-sampling rate data fusion. By synchronously collecting voltage and current data from different measuring points within the same system, it analyzes the preliminary true frequency and preliminary distorted frequency of abnormal harmonic content. Combined with an equivalent impedance model established using grid parameters, it further verifies the true frequency of abnormal harmonic content using harmonic impedance characteristics and harmonic transitivity. This solves the problem of difficulty in identifying resonant frequencies due to differences in the sampling rates of monitoring devices. Simultaneously, by utilizing multi-sampling rate harmonic monitoring data and grid parameters, it achieves accurate identification of the true resonant frequency of the substation, resolving the issues of inconsistent harmonic spectrum analysis results and unclear true resonant frequencies caused by differences in the sampling rates of monitoring devices. This effectively improves the accuracy and reliability of resonant frequency identification under multi-sampling rate monitoring conditions, providing technical support for high-frequency resonance monitoring and tracing in new power systems.

[0079] In one possible implementation, the frequency determination module can specifically be used for: The first time-domain waveform data of the first measurement point of the substation to be identified is acquired, and the first time-domain waveform data is converted into first frequency-domain data through discrete Fourier transform. The first time-domain waveform data includes the first voltage and the first current. The second time-domain waveform data of the second measuring point of the substation to be identified is acquired synchronously, and the second time-domain waveform data is converted into second frequency-domain data through discrete Fourier transform. The second time-domain waveform data includes the second voltage and the second current. Based on the first frequency domain data, determine the first frequency of the abnormal harmonic content; Based on the second frequency domain data, the second frequency with abnormal harmonic content was determined.

[0080] In one possible implementation, the frequency determination module can be used to: Input the first time-domain waveform data into the first formula to obtain the first frequency-domain data. The first formula is:

[0081]

[0082] in, The first measuring point of the substation to be identified Root mean square value of second harmonic voltage The first voltage, This represents the number of sampling points for the discrete-time signal of the voltage or current waveform. This is the number of the discrete-time signal. For harmonic order, The first measuring point of the substation to be identified Root mean square value of second harmonic current For the first current, The imaginary unit, To obtain the modulus of the phasor, It is a natural constant.

[0083] In one possible implementation, the preliminary judgment module can be used specifically for: Determine whether the first frequency is less than the second frequency; If the first frequency is less than the second frequency, then the preliminary true frequency and the preliminary distortion frequency are determined based on the first frequency and the second frequency.

[0084] In one possible implementation, the preliminary judgment module can be used for: Input the first frequency and the second frequency into the second formula, where the second formula is:

[0085] in, For the first frequency, For the second frequency, It is a minimum value function. The sampling frequency of the first measurement point is... For integer variables, It is an integer. It is an absolute value function; If the second formula holds true, then the second frequency is determined as the preliminary true frequency, and the first frequency is determined as the preliminary distortion frequency.

[0086] In one possible implementation, the frequency calculation module can be used for: Collect the physical parameters of the substation to be identified, including transformer impedance voltage, transformer medium-voltage side rated voltage, transformer medium-voltage side rated capacity, and system short-circuit capacity. Using physical parameters, construct an equivalent impedance model.

[0087] In one possible implementation, the preliminary judgment module can also be used for: Based on the equivalent impedance model, the target equivalent harmonic impedance and the target harmonic voltage transfer coefficient are calculated. The target equivalent harmonic impedance is the impedance from the low-voltage load side of the transformer to the high- and medium-voltage sides of the transformer. The equivalent harmonic impedance and the target harmonic voltage transfer coefficient are derived from the low-voltage load side of the transformer to the high, medium, and low-voltage busbars of the transformer, as well as the medium-voltage substation busbar. Subharmonic voltage transfer coefficient; When the amplitude of the target equivalent harmonic impedance is at its minimum and the target harmonic voltage transfer coefficient is at its maximum, the target harmonic frequency in which the harmonic anomaly occurs is determined. The third frequency is calculated using the target harmonic frequency.

[0088] In one possible implementation, the preliminary judgment module can also be used for: Based on the equivalent impedance model, the first equivalent harmonic impedance, the second equivalent harmonic impedance, and the third equivalent harmonic impedance are calculated respectively. The first equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer high-voltage side. The second equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer medium-voltage side. The second equivalent harmonic impedance and the third equivalent harmonic impedance are the impedance from the transformer neutral point to the low-voltage side of the transformer. Subequivalent harmonic impedance; The first, second, and third equivalent harmonic impedances are input into the third formula to calculate the target equivalent harmonic impedance. The third formula is as follows:

[0089] in, For the target equivalent harmonic impedance, The first equivalent harmonic impedance, The second equivalent harmonic impedance, The third equivalent harmonic impedance, This is the impedance parallel operator.

[0090] In one possible implementation, the target harmonic voltage transfer coefficient includes a first harmonic voltage transfer coefficient, a second harmonic voltage transfer coefficient, a third harmonic voltage transfer coefficient, and a fourth harmonic voltage transfer coefficient; the preliminary judgment module can also be used for: The first harmonic voltage transfer coefficient is calculated using the fourth formula, which is:

[0091] in, The first harmonic voltage transfer coefficient, For transformers to higher systems Subequivalent harmonic impedance; The second harmonic voltage transfer coefficient is calculated using the fifth formula, which is:

[0092] in, The second harmonic voltage transfer coefficient, For medium-voltage side substations Secondary equivalent load impedance From the medium-voltage side busbar of the transformer to the medium-voltage side substation Secondary equivalent load impedance; The third harmonic voltage transfer coefficient is calculated using the sixth formula, which is:

[0093] in, The third harmonic voltage transfer coefficient. For harmonic order, This refers to the fundamental short-circuit impedance on the low-voltage side of the transformer. The imaginary unit; The fourth harmonic voltage transfer coefficient is calculated using the seventh formula, which is:

[0094] in, This is the fourth harmonic voltage transfer coefficient.

[0095] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0096] Those skilled in the art will recognize that the templates, units, and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0097] If the module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the above embodiments of the substation resonant frequency identification method for multi-sampling rate data fusion. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0098] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for identifying the resonant frequency of a substation using multi-sampling-rate data fusion, characterized in that, include: The time-domain waveform data of the first and second measuring points of the substation to be identified are acquired simultaneously to determine the first and second frequencies of abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified. The time-domain waveform data includes voltage and current. Based on the first frequency and the second frequency, a preliminary true frequency and a preliminary distortion frequency are determined, wherein the preliminary distortion frequency is a frequency that is superimposed on the preliminary true frequency to a lower frequency. Construct an equivalent impedance model of the substation to be identified, and determine the third frequency of abnormal harmonic content based on the equivalent impedance model; Based on the third frequency, the preliminary true frequency, and the preliminary distorted frequency, the harmonic abnormal frequency of the substation to be identified is determined.

2. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 1, characterized in that, The process of synchronously acquiring time-domain waveform data from the first and second measuring points of the substation to be identified, and determining the first and second frequencies of abnormal harmonic content, includes: The first time-domain waveform data of the first measuring point of the substation to be identified is obtained, and the first time-domain waveform data is converted into first frequency-domain data through discrete Fourier transform. The first time-domain waveform data includes a first voltage and a first current. The second time-domain waveform data of the second measuring point of the substation to be identified is acquired synchronously, and the second time-domain waveform data is converted into second frequency-domain data through the discrete Fourier transform. The second time-domain waveform data includes the second voltage and the second current. Based on the first frequency domain data, determine the first frequency with abnormal harmonic content; Based on the second frequency domain data, the second frequency with abnormal harmonic content is determined.

3. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 2, characterized in that, The step of converting the first time-domain waveform data into the first frequency-domain data through discrete Fourier transform includes: The first time-domain waveform data is input into the first formula to obtain the first frequency-domain data. The first formula is: in, The first measuring point of the substation to be identified Root mean square value of second harmonic voltage The first voltage, This represents the number of sampling points for the discrete-time signal of the voltage or current waveform. This is the number of the discrete-time signal. For harmonic order, The first measuring point of the substation to be identified Root mean square value of second harmonic current For the first current, The imaginary unit, To obtain the modulus of the phasor, It is a natural constant.

4. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 1, characterized in that, The step of determining the preliminary true frequency and the preliminary distortion frequency based on the first frequency and the second frequency includes: Determine whether the first frequency is less than the second frequency; If the first frequency is less than the second frequency, then the preliminary true frequency and the preliminary distortion frequency are determined based on the first frequency and the second frequency.

5. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 4, characterized in that, The step of determining the preliminary true frequency and the preliminary distorted frequency based on the first frequency and the second frequency includes: The first frequency and the second frequency are input into the second formula, wherein the second formula is: in, For the first frequency, For the second frequency, It is a minimum value function. The sampling frequency of the first measuring point is... For integer variables, It is an integer. It is an absolute value function; If the second formula holds true, then the second frequency is determined as the preliminary true frequency, and the first frequency is determined as the preliminary distortion frequency.

6. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 1, characterized in that, The construction of the equivalent impedance model of the substation to be identified includes: The physical parameters of the substation to be identified are collected, including transformer impedance voltage, transformer medium-voltage side rated voltage, transformer medium-voltage side rated capacity, and system short-circuit capacity. The equivalent impedance model is constructed using the physical parameters.

7. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 1, characterized in that, The determination of the third frequency with abnormal harmonic content based on the equivalent impedance model includes: Based on the equivalent impedance model, the target equivalent harmonic impedance and the target harmonic voltage transfer coefficient are calculated. The target equivalent harmonic impedance is the impedance from the low-voltage load side of the transformer to the high- and medium-voltage sides of the transformer. The second equivalent harmonic impedance, the target harmonic voltage transfer coefficient is from the low-voltage load side of the transformer to the high, medium, and low-voltage busbars of the transformer and the medium-voltage substation busbar. Subharmonic voltage transfer coefficient; When the amplitude of the target equivalent harmonic impedance is at its minimum and the target harmonic voltage transfer coefficient is at its maximum, the target harmonic frequency in which the harmonic anomaly occurs is determined. The third frequency is calculated using the target harmonic frequency.

8. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 7, characterized in that, The calculation of the target equivalent harmonic impedance includes: Based on the equivalent impedance model, the first equivalent harmonic impedance, the second equivalent harmonic impedance, and the third equivalent harmonic impedance are calculated respectively. The first equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer high-voltage side. The second equivalent harmonic impedance is the impedance from the transformer neutral point to the transformer medium-voltage side. The third equivalent harmonic impedance is the impedance from the transformer neutral point to the low-voltage side of the transformer. Subequivalent harmonic impedance; The first equivalent harmonic impedance, the second equivalent harmonic impedance, and the third equivalent harmonic impedance are input into the third formula to calculate the target equivalent harmonic impedance. The third formula is as follows: in, The target is the equivalent harmonic impedance. The first equivalent harmonic impedance, This is the second equivalent harmonic impedance. The third equivalent harmonic impedance, This is the impedance parallel operator.

9. The substation resonant frequency identification method based on multi-sampling rate data fusion according to claim 8, characterized in that, The target harmonic voltage transfer coefficient includes a first harmonic voltage transfer coefficient, a second harmonic voltage transfer coefficient, a third harmonic voltage transfer coefficient, and a fourth harmonic voltage transfer coefficient. The calculation of the target harmonic voltage transfer coefficient includes: The first harmonic voltage transfer coefficient is calculated using a fourth formula, which is: in, The first harmonic voltage transfer coefficient is... For transformers to higher systems Subequivalent harmonic impedance; The second harmonic voltage transfer coefficient is calculated using the fifth formula, which is: in, The second harmonic voltage transfer coefficient. For medium-voltage side substations Secondary equivalent load impedance From the medium-voltage side busbar of the transformer to the medium-voltage side substation Secondary equivalent load impedance; The third harmonic voltage transfer coefficient is calculated using the sixth formula, which is: in, The third harmonic voltage transfer coefficient is... For harmonic order, This refers to the fundamental short-circuit impedance on the low-voltage side of the transformer. The imaginary unit; The fourth harmonic voltage transfer coefficient is calculated using the seventh formula, which is: in, The fourth harmonic voltage transfer coefficient is given.

10. A substation resonant frequency identification device based on multi-sampling rate data fusion, characterized in that, include: The frequency determination module is used to synchronously acquire time-domain waveform data of the first and second measuring points of the substation to be identified, and determine the first and second frequencies with abnormal harmonic content. The first and second measuring points are adjacent measuring points of the substation to be identified. The time-domain waveform data includes voltage and current. The preliminary judgment module is used to determine a preliminary true frequency and a preliminary distortion frequency based on the first frequency and the second frequency, wherein the preliminary distortion frequency is a frequency that is superimposed on the preliminary true frequency to a low frequency. The frequency calculation module is used to construct the equivalent impedance model of the substation to be identified, and based on the equivalent impedance model, determine the third frequency of abnormal harmonic content. The frequency identification module is used to identify the harmonic abnormal frequency of the substation to be identified based on the third frequency, the preliminary true frequency, and the preliminary distorted frequency.

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