Intelligent relay protection device and method for turn-to-turn short circuit of dry-type air-core reactor

Abstract

The invention relates to the technical field of power electronic component manufacturing, in particular to an intelligent relay protection device and method for turn-to-turn short circuit of a dry-type air-core reactor, the device is used for fault detection and relay protection of the dry-type air-core reactor, and the device is composed of a data acquisition unit, a host unit, a communication unit, a relay protection unit and a power supply unit; the host unit processes and analyzes the received power data acquired by the data acquisition unit, and constructs a window with an adaptive size and a polynomial order to filter and denoise the power data by analyzing change characteristics and noise interference characteristics of the power data in the dry-type air-core reactor in each interval; and performing turn-to-turn short circuit fault judgment and relay protection on the dry-type air-core reactor by using the denoised power data. The invention aims to prevent SG filtering from excessively smoothing fault features in power data and improve the availability of voltage and current data in subsequent turn-to-turn short circuit fault identification.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power electronic component manufacturing, in particular to an intelligent relay protection device and method for turn-to-turn short circuit of a dry-type air-core reactor. BACKGROUND

[0002] In recent years, with the development of power systems in the direction of high voltage and long distance transmission, dry-type air-core reactors have the advantages of simple structure, good linearity and easy maintenance, and are usually based on multiple reactors to build a parallel reactor group to compensate for the reactive power in the power line, and are widely used in power systems. The most common fault of the dry-type air-core reactor is the local short circuit caused by the failure of the insulation between the adjacent turns of the winding. At the initial stage of the turn-to-turn short circuit fault, the current flowing through the reactor changes very little, which makes it difficult to identify the initial small changes and trigger the overcurrent protection action in time, and the protection is triggered only when the fault gradually develops into a single-phase short circuit or a relative ground short circuit, resulting in serious accidents and affecting the normal operation of the power system.

[0003] The turn-to-turn short circuit fault of the dry-type air-core reactor does not show obvious changes in current data characteristics in the early stage. The existing fault detection methods often use single threshold-based relay protection for judgment. Due to the voltage fluctuations and abnormal disturbances in the power system, the features that can be used for fault detection in the current data are overwhelmed by the fluctuation and disturbance features of the power system, and the traditional turn-to-turn short circuit fault detection method for the reactor cannot detect the early signs of the fault, which makes it difficult to set an appropriate threshold for the relay protection of the reactor. In order to improve the usability of the current data, denoising of the data signal is one of the effective means. The traditional SG filter denoising method filters and denoises the voltage and current data of the reactor based on a fixed filter window length and multiple orders, which makes it difficult to identify the early fault data features and disturbance features, and the available fault features are easily smoothed out, affecting the subsequent identification of the turn-to-turn short circuit fault of the reactor. SUMMARY

[0004] To solve the above technical problems, the application provides an intelligent relay protection device and method for turn-to-turn short circuit of a dry-type air-core reactor, and the technical solutions adopted are as follows: In a first aspect, the application provides an intelligent relay protection method for turn-to-turn short circuit of a dry-type air-core reactor, which comprises the following steps: Step one: collecting power data of the dry-type air-core reactor and preprocessing; Step two: decomposing each kind of power data into multiple IMF components by using variational mode decomposition, and dividing intervals; Step three: the symmetry and peak variation of each IMF component of the power data in each interval are analyzed in turn by using the difference between the absolute value of the mean value of the power data amplitude and the mean value of the power data amplitude absolute value, and the power data amplitude change difference between adjacent peaks, and are fused into a first feature index; Step four: the window size of the SG filter on each interval is adaptively adjusted by using the first feature index, and the polynomial order of the SG filter in each interval is adaptively adjusted by using the spectral entropy feature of each IMF component of the power data in each interval; then each IMF component of the power data in each interval is filtered by using the improved SG filter, and the denoised IMF components are reconstructed to obtain the power data; Step five: the power factor change amount of the filtered and reconstructed power data is analyzed to determine whether there is a turn-to-turn short circuit fault; if it is determined that a fault occurs, the relay protection action is triggered.

[0005] Preferably, the power data includes voltage and current data of the dry-type air-core reactor.

[0006] Preferably, the preprocessing includes time series reconstruction and alignment preprocessing of the voltage and current data respectively; the reconstruction reconstructs the voltage and current data into continuous time series by the sinc interpolation method, and the alignment ensures the synchronization consistency of the voltage and current data by using the dynamic time planning algorithm.

[0007] Preferably, the fusion method of the first feature index is: ; wherein is an exponential function with the natural constant e as the base, represents the symmetry of the i-th IMF component of the current data in the j-th interval, represents the peak variation of the i-th IMF component of the current data in the j-th interval.

[0008] Preferably, the symmetry is calculated by the ratio of the absolute value of the mean value of the current amplitude of each IMF component of the current data at all times in each interval to the mean value of the absolute value of the current amplitude at all times.

[0009] Preferably, the peak variation is determined by the mean value of the absolute difference between all adjacent two local extreme points in each interval.

[0010] Preferably, the window size of the SG filter is adaptively adjusted according to the linear interpolation of the first feature index between the preset maximum value and the minimum value.

[0011] ​​​​Preferably, the polynomial order is set according to the normalized value of the spectral entropy feature of all intervals, and the higher the spectral entropy, the lower the polynomial order.

[0012] Preferably, the method for obtaining the spectral entropy is: obtaining the instantaneous frequency of each sampling point of each IMF component of the power data in each interval by using Hilbert transform; and calculating the spectral entropy according to the instantaneous frequency distribution of all sampling points in each interval.

[0013] In a second aspect, the embodiments of the present application also provide a turn-to-turn short circuit intelligent relay protection device for a dry-type air-core reactor, which is used for fault detection and relay protection of the dry-type air-core reactor and is composed of a data acquisition unit, a host unit, a communication unit, a relay protection unit and a power supply unit; The data acquisition unit comprises a voltage and current data acquisition module, which acquires voltage and current data of the reactor through a voltage transformer and a current transformer; The host unit adopts an industrial-grade embedded processor, is used for receiving and processing the data acquired by the data acquisition unit, performs real-time analysis on the data change of the dry-type air-core reactor by using the above-mentioned method for intelligent relay protection of a turn-to-turn short circuit of a dry-type air-core reactor, and outputs a control command for the dry-type air-core reactor; The communication unit is responsible for uploading the acquired data and detection results to a power management center through a wireless network; The relay protection unit performs relay protection on the dry-type air-core reactor through the control command output by the host unit, so as to avoid major accidents caused by turn-to-turn short circuit faults; The power supply unit is a 220V power supply for separately supplying power to the relay protection device.

[0014] The present application has at least the following beneficial effects: The present application considers analyzing the waveform data features and frequency domain data features of the power data in each interval of the power data, constructing an adaptive filtering window and a polynomial order, effectively eliminating noise interference in high-noise interval data, avoiding noise interference from being identified as a short circuit fault feature, performing more detailed fitting in the real short circuit fault data interval, retaining the power data change features of the turn-to-turn short circuit fault to the greatest extent, avoiding the power data from being excessively smoothed by the SG filter, and improving the usability of the voltage and current data for subsequent turn-to-turn short circuit fault identification. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0016] Figure 1 A schematic diagram of an internal unit of a turn-to-turn short-circuit intelligent relay protection device of a dry-type air-core reactor according to the present application; Figure 2 A flow chart of steps of a turn-to-turn short-circuit intelligent relay protection method of a dry-type air-core reactor according to the present application. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purposes, the specific implementation, structure, features and effects of the turn-to-turn short-circuit intelligent relay protection device and method of a dry-type air-core reactor according to the present application will be described in detail below in combination with the drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0019] The specific scheme of the turn-to-turn short-circuit intelligent relay protection device and method of a dry-type air-core reactor according to the present application will be specifically described below in combination with the drawings.

[0020] The present application provides a turn-to-turn short-circuit intelligent relay protection device for a dry-type air-core reactor, hereinafter referred to as a relay protection device. The relay protection device is used for fault detection and relay protection of a dry-type air-core reactor and is composed of a data acquisition unit, a host unit, a communication unit, a relay protection unit and a power supply unit.

[0021] The data acquisition unit includes a voltage and current data acquisition module. The voltage and current acquisition module acquires voltage and current data of the reactor through a voltage transformer and a current transformer.

[0022] The host unit adopts an industrial-grade embedded processor and is used for receiving and processing the data acquired by the data acquisition unit. The host unit can perform synchronous sampling, data calculation and analysis and other operations on the data. The host unit performs real-time analysis on the data changes of the dry-type air-core reactor by using the dry-type air-core reactor turn-to-turn short-circuit fault detection method designed by the present application and outputs control commands for the dry-type air-core reactor.

[0023] The communication unit is responsible for uploading the collected data and detection results to the power management center through a wireless network.

[0024] The relay protection unit performs relay protection on the dry-type air-core reactor through the control command output by the host unit, to avoid major accidents caused by turn-to-turn short circuit faults.

[0025] The power supply unit is a 220V power supply that supplies power to the relay protection device independently.

[0026] The relay protection device housing adopts at least IP54 or IP65 level and has electromagnetic anti-interference capability, to avoid electromagnetic shock in high-voltage power lines from damaging the normal operation of the relay protection device.

[0027] The device control process is: equipment power-on → multi-channel data sampling → data preprocessing → data feature analysis → fault determination → the device performs relay protection → data transmission, to realize full-process monitoring and turn-to-turn short circuit fault discrimination of the dry-type air-core reactor.

[0028] See the attached Figure 1 The embodiment provides a schematic diagram of a built-in unit of a relay protection device.

[0029] Another embodiment of the application provides an intelligent turn-to-turn short circuit relay protection method for a dry-type air-core reactor. Please refer to Figure 2 The method comprises the following steps: Step 1: Collecting power data of the dry-type air-core reactor and performing preprocessing.

[0030] The power data of the dry-type air-core reactor are obtained by a data acquisition unit in an intelligent turn-to-turn short circuit relay protection device (hereinafter referred to as a relay protection device) for the dry-type air-core reactor, and the power data include voltage and current data of the dry-type air-core reactor.

[0031] Among them, the sampling frequency of voltage and current is 10 kHz, and the time window length of data analysis is 5 minutes. The sampling frequency and the size of the analysis time window can be set by the implementer according to the implementation scene, and there is no special limitation, but in order to ensure the reliability of the collected signal, the sampling frequency should meet the Nyquist sampling theorem.

[0032] Then the voltage and current data are respectively reconstructed into continuous time series signals by using the sinc interpolation method. The sinc interpolation method is prior art, and its specific process will not be repeated here.

[0033] The obtained time series signals are aligned by using the dynamic time planning algorithm to ensure the synchronization consistency of the data. The dynamic time planning algorithm is prior art, and its specific process will not be repeated here.

[0034] Step two: by analyzing the change characteristics and noise interference characteristics of the power data in each interval of the dry-type air-core reactor, a self-adaptive size window and a polynomial order are constructed to filter and denoise the power data.

[0035] In the detection of turn-to-turn short-circuit fault of the dry-type air-core reactor, the early change characteristics of the power data are small, and there are noise interferences in the process of high-voltage power line and reactor, such as the dry-type air-core reactor with a hollow structure, the magnetic flux leakage is large, which causes the conductors or sensors around the reactor to induce random electromagnetic coupling interference due to the magnetic flux leakage. This interference noise is superimposed in the current or voltage waveform, so that the small power data change characteristics in the early stage of turn-to-turn short-circuit fault are covered by noise. The traditional SG filtering uses a fixed window length and a polynomial order to smooth the signal data. If the window length is too large or the polynomial order is too low, the current change characteristics caused by the early turn-to-turn short-circuit fault will be smoothed, and the authenticity of the data will be lost. On the contrary, if the window length is too small or the polynomial order is too high, the interference caused by random noise cannot be effectively filtered out.

[0036] To solve the above problems, the present application constructs a self-adaptive size window and a polynomial order to filter and denoise the voltage and current data by analyzing the change characteristics and noise interference characteristics of the voltage and current data in each interval of the dry-type air-core reactor. This can effectively eliminate noise interference in high-noise interval data, avoid noise interference from being identified as short-circuit fault characteristics, and at the same time, preserve the power data change characteristics of the turn-to-turn short-circuit fault to the greatest extent in the real short-circuit fault interval, avoiding the over-smoothing of the fault characteristics by SG filtering and damaging the usability of the subsequent turn-to-turn short-circuit fault identification.

[0037] Firstly, the voltage and current data in the reactor are represented as , wherein , respectively represent the voltage and current data at the time, the time order of is 1ms, represents the total number of sampling points under the whole data analysis time window.

[0038] Considering the complex multi-frequency interference caused by the impact interference in the power system line and the random interference caused by electromagnetic coupling in the reactor on the voltage and current data, it is difficult to accurately analyze the change characteristics and noise interference characteristics of the voltage and current in the whole power transmission signal. The present application uses variational mode decomposition to decompose the voltage and current data respectively, and obtains IMF components, The size of can be set by the implementer according to the implementation scenario, and is not specially limited. In this embodiment, The size is set to 6. Complex power data signals are decomposed into multiple IMF components at different frequency bands, facilitating the analysis of interference noise characteristics and power data variation characteristics at each component level.

[0039] Taking current data denoising as an example, The Each IMF component is represented as ,Will According to length Divided into equal-length intervals, a total of Each interval Its size can be set by the implementer according to the implementation scenario, without special restrictions. In this embodiment, The size is 2 seconds. The first IMF component In each interval The current data at time t is represented as .

[0040] In a normal reactor, the current flowing through it remains stable. When an inter-turn short-circuit fault occurs, the local insulation layer between the turns is broken down, leading to an increase in local circulating current. This causes a slight distortion in the current waveform and enhances the asymmetry of the current data. Electromagnetic interference and impacts in the power system lines can also cause random fluctuations in the current waveform. Therefore, the asymmetry of the current waveform can be used as one of the indicators for evaluating data characteristics.

[0041] Among them, the current data of the first The IMF component in the first Symmetry of each interval It can be represented as: in, The first representing the current data The IMF component in the first The absolute value of the mean of the current amplitude at all times within each interval. The first representing the current data The IMF component in the first The mean of the absolute values ​​of the current amplitude at all times within a given interval. The value indicates the degree of bias in the current data waveform. A larger value indicates that the waveform is biased to one side. The meaning is used to indicate the use of Normalization is performed.

[0042] The closer the value is to 0, the better the symmetry of the IMF component of the current data in that interval, and the less fault characteristics or noise interference characteristics there are in that interval. When the data is close to zero, the waveform remains a standard sine wave; however, when there is significant noise interference in this range, the waveform characteristics exhibit irregular changes, with the current IMF component waveform shifting towards one side. The larger the value between (0,1), the greater the proportion of bias energy caused by the change in data waveform due to inter-turn short circuit fault or the influence of noise, resulting in a worse symmetry of the current IMF component waveform.

[0043] Furthermore, since both inter-turn short-circuit faults and noise interference disrupt the symmetry of the waveform characteristics of the current IMF component data, it is difficult to accurately determine whether the abnormal data characteristics in this interval are noise interference based solely on waveform symmetry indicators, making it impossible to set an appropriate window size for filtering. Considering that inter-turn short-circuit faults generate harmonic interference in the power data, and that the current data gradually increases to the point of causing a major accident with overcurrent, this phenomenon causes the reactor current data to show a trend of increasing, while electromagnetic coupling interference and other noise effects present random noise impacts in the power data. Therefore, this application further determines whether there is noise interference in the abnormal waveform interval data based on the variation and fluctuation of the peak values ​​of each waveform in the current IMF component.

[0044] For any one Any sampling point in the interval If the current amplitude at the point satisfies Then record the sampling point. For a local extremum point, obtain The number of all local extreme points in the interval is denoted as . indivual.

[0045] The first current data The IMF component in the first Peak variability of each interval It can be represented as: in , These represent the first and second data points of the current data. The IMF component in the first In the interval, the first The, the The difference between the current amplitudes at local extreme points represents the magnitude of the change between two consecutive local extreme points of the current. Finally, the mean of the absolute differences between all adjacent local extreme points in the entire interval represents the variability of the current peak value in the interval of the current IMF component data.

[0046] The larger, the more The greater the variation degree of the current peak value in the interval, the stronger the random noise impact caused by electromagnetic coupling, and vice versa The smaller the variation degree of the current peak value in the interval, the slower the trend change of the peak value of the current caused by the inter-turn short circuit fault.

[0047] In summary, the first characteristic index of the interval can be expressed as: wherein is an exponential function with the natural constant e as the base, and the purpose is to normalize to the order of magnitude [0, 1] for easy calculation with . The thus constructed is proportional to and . When the symmetry of the current IMF component waveform in the interval is worse and the variation degree of the current peak value is greater, the greater, indicating that there is a large amount of noise interference in the interval, and vice versa, indicating that the interval is normal current or inter-turn short circuit fault characteristics.

[0048] The adaptive filter window size of the SG filter in the interval can be expressed as: wherein and are the maximum and minimum values of the filter window of the SG filter, respectively, and the size is an odd number in the value range, which can be set by the implementer according to the implementation scenario, and is not specially limited. In the present embodiment, the size of and

[0049] is set to 63 and 7, respectively. When there is a large amount of noise interference in the interval, in order to better smooth and eliminate the random noise interference signal in the interval, the greater, the larger the final filter window size; on the contrary, when the interval is mostly normal current data characteristics and inter-turn short circuit fault characteristics, the smaller, then in order to avoid the SG filter smoothing and filtering out the slowly changing current characteristics, the final filter window is smaller.

[0050] Further, in the early inter-turn short circuit fault of the dry-type air-core reactor, the signal spectrum entropy reflects the complexity of the current data spectrum distribution, the interval with smaller spectrum entropy indicates that the signal spectrum ability is mostly concentrated in a few frequency components, then the signal data changes more smoothly and stably, otherwise, when the spectrum entropy is larger, it indicates that the signal contains more random noise interference, the spectrum energy distribution is discrete, if a higher polynomial order is used for fitting filtering, it will cause the filtered signal to retain more details, and it is difficult to filter out the noise signal.

[0051] According to the spectrum entropy characteristics in each interval of the current IMF component, the polynomial order in each interval is adaptively adjusted.

[0052] The Hilbert transform is performed on to obtain the instantaneous frequency of each sampling point in the interval. The Hilbert transform is a prior art, and its specific process will not be repeated.

[0053] Further, according to the instantaneous frequency distribution of all sampling points in the interval , the spectrum entropy is obtained. The method for obtaining the spectrum entropy of the instantaneous frequency of the sampling points is a prior art, and its specific process will not be repeated. The spectrum entropy of all intervals is obtained. The maximum and minimum normalization processing is performed on to obtain the normalized spectrum entropy of the interval .

[0054] The adaptive polynomial order of the SG filtering in the interval can be expressed as: wherein is a preset polynomial order initial value of the SG filtering, which can be set by the implementer according to the implementation scene, and is not specially limited, and in the embodiment, the value is 2.

[0055] In this way, the can be adaptively adjusted according to the spectrum entropy in the interval . When the spectrum entropy is larger, it indicates that the signal frequency distribution in the interval is more complex, in order to avoid that the SG filtering retains too many detail characteristics when performing binomial fitting, and cannot effectively filter out the noise signal, a smaller polynomial order is used for smoothing processing, otherwise when the spectrum entropy is smaller, it indicates that the signal frequency distribution in the interval is more concentrated, in order to retain the detail current change characteristics as much as possible, a larger polynomial order is used to perform more fine fitting on the data in the interval, so as to avoid that the inter-turn short circuit fault characteristics are filtered out.

[0056] Finally, the adaptive filter window and the adaptive polynomial order of each interval obtained in the above steps are substituted into the SG filter to filter and denoise each IMF component of the current data, and each IMF component after denoising is reconstructed to obtain the denoised current data. The IMF component reconstruction method is prior art, and its specific process will not be described again.

[0057] The above steps are repeated to denoise the voltage data, and finally the denoised voltage and current data are obtained.

[0058] Step three: Based on the denoised power data, the turn-to-turn short-circuit fault of the dry-type air-core reactor is judged and the relay protection is performed.

[0059] The denoised voltage and current data are calculated by the host unit of the relay protection device to determine whether a turn-to-turn short-circuit fault occurs.

[0060] The method for judging the turn-to-turn short-circuit fault refers to the relay protection action method described in the patent "CN109473949B Dry-type air-core shunt reactor set turn-to-turn short-circuit fault relay protection method and device". When the power factor change amount of the dry-type air-core reactor is greater than a set threshold, it is determined that a turn-to-turn short-circuit fault of the dry-type air-core reactor occurs, wherein the set threshold is the minimum value of the power factor change amount. The specific calculation method of the power factor of the dry-type air-core reactor and the setting method of the minimum value of the power factor change amount are described in the patent, and the specific process will not be described again.

[0061] If a turn-to-turn short-circuit fault occurs, the relay protection device controls the relay protection unit to perform relay protection on the reactor through the host unit.

[0062] Each embodiment in the present application is described in a progressive manner, and the same and similar parts between each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments.

[0063] It should be noted that unless otherwise specified and limited, terms such as "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the circuit structure, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such article or device. Without more limitation, the element limited by the statement "including a" does not exclude the presence of another identical element in the article or device including the element. In addition, the term "and / or" used herein includes any and all combinations of one or more related listed items.

[0064] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.

[0065] It should be understood that the application is not limited to the precise construction and compositions described above and shown in the attached drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application.

Claims

1. A method for intelligent relay protection of inter-turn short circuits in a dry-type air-core reactor, characterized in that, The method includes the following steps: Collect and preprocess the power data of the dry-type air-core reactor; Variational mode decomposition is used to decompose each type of power data into multiple IMF components and divide them into intervals; By utilizing the difference between the absolute value of the mean amplitude of power data and the mean of the absolute values ​​of power data amplitude, as well as the difference in amplitude variation of power data between adjacent peaks, the symmetry and peak variability of each IMF component of power data in each interval are analyzed sequentially and fused into the first feature index. The window size of the SG filter in each interval is adaptively adjusted using the first feature index, and the polynomial order of the SG filter in each interval is adaptively adjusted using the spectral entropy feature of each IMF component of the power data in each interval. Then, the improved SG filter is used to filter each IMF component of the power data in each interval, and the power data is reconstructed from the denoised IMF components. The power factor change is analyzed on the filtered and reconstructed power data to determine whether there is an inter-turn short circuit fault; if a fault is determined to have occurred, the relay protection is triggered.

2. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 1, characterized in that, The power data includes the voltage and current data of the dry-type air-core reactor.

3. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 2, characterized in that, The preprocessing includes time series reconstruction and alignment preprocessing of voltage and current data respectively; the reconstruction uses sinc interpolation to reconstruct voltage and current data into a continuous time series, and the alignment uses a dynamic time planning algorithm to ensure the synchronization and consistency of voltage and current data.

4. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 2, characterized in that, The fusion method for the first feature index is as follows: ;in It is an exponential function with the natural constant e as the base. The first representing the current data The IMF component in the first Symmetry of each interval The first representing the current data The IMF component in the first Peak variability in each interval.

5. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 4, characterized in that, The symmetry is calculated by the ratio of the absolute value of the mean current amplitude of each IMF component of the current data at all times in each interval to the mean of the absolute values ​​of the current amplitude at all times.

6. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 4, characterized in that, The peak variability is determined by the mean of the absolute differences between all two adjacent local extrema in each interval for each IMF component of the current data.

7. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 1, characterized in that, The window size of the SG filter is adaptively adjusted by linear interpolation between a preset maximum and minimum value based on a first feature index.

8. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 1, characterized in that, The polynomial order is set hierarchically based on the normalized value of the spectral entropy characteristics of all intervals; the higher the spectral entropy, the lower the polynomial order.

9. The intelligent relay protection method for inter-turn short circuit of a dry-type air-core reactor as described in claim 8, characterized in that, The method for obtaining the spectral entropy is as follows: using Hilbert transform, the instantaneous frequency of each IMF component of the power data at each sampling point in each interval is obtained; based on the instantaneous frequency distribution of all sampling points in each interval, its spectral entropy is calculated.

10. A smart relay protection device for inter-turn short circuit of a dry-type air-core reactor, characterized in that, This device is used for fault detection and relay protection of dry-type air-core reactors, and consists of a data acquisition unit, a host unit, a communication unit, a relay protection unit, and a power supply unit. The data acquisition unit includes a voltage and current data acquisition module, which acquires the voltage and current data of the reactor through a voltage transformer and a current transformer. The host unit uses an industrial-grade embedded processor to receive and process the data collected by the data acquisition unit. It uses the inter-turn short-circuit intelligent relay protection method for dry-type air-core reactors as described in any one of claims 1-9 to perform real-time analysis of data changes in dry-type air-core reactors and output control commands for the dry-type air-core reactors. The communication unit is responsible for uploading the collected data and test results to the power management center via a wireless network. The relay protection unit provides relay protection for the dry-type air-core reactor through the control commands output by the main unit, so as to avoid major accidents caused by inter-turn short circuit faults. The power supply unit is a 220V power supply that provides separate power to the relay protection device.

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