Hydro-generator ultrahigh frequency partial discharge identification method based on attenuation coefficient correction

Abstract

The invention provides a hydro-generator ultrahigh frequency partial discharge identification method based on attenuation coefficient correction, and belongs to the technical field of partial discharge signal measurement. The method comprises the following steps: acquiring a partial discharge test signal which is acquired at an acquisition point and is transmitted by a stator bar, analyzing the acquired partial discharge test signal to obtain a transfer function and a signal attenuation coefficient of a signal transmission path between an injection point and the acquisition point, and injecting the partial discharge test signal into the stator bar from the injection point, an injection point is arranged at the suspended part of the head end of the stator bar; acquiring a partial discharge signal under an actual working condition; reconstructing and correcting the partial discharge signal by using the maximum signal attenuation coefficient and the corresponding transfer function; and comparing the amplitude of the corrected partial discharge signal with the typical partial discharge amplitude, and judging whether a partial discharge event occurs in the stator bar. Based on the method, quantitative analysis of the insulation state of the stator bar is achieved, the requirement for the ability of technicians on a monitoring site is lowered, and the applicability is higher.

Description

Technical Field

[0001] The present application belongs to the field of ultra-high frequency partial discharge measurement technology, and specifically relates to an ultra-high frequency partial discharge identification method for a hydro-turbine generator based on attenuation coefficient correction, an ultra-high frequency partial discharge identification device for a hydro-turbine generator based on attenuation coefficient correction, a machine-readable storage medium, and a computer device. Background Art

[0002] The partial discharge test of hydro-turbine generators is used to diagnose early insulation faults. At present, the mainstream partial discharge test equipment in the market mainly adopts low-frequency partial discharge test technology, and its frequency range is 10kHz to 500kHz. When applied to hydro-turbine generators, the monitored test data fluctuates greatly due to the influence of interference signals during the operation stage of the generator, resulting in problems such as difficulty in identifying partial discharge patterns. In order to overcome the above-mentioned defects of low-frequency partial discharge test technology, many scholars have carried out research on ultra-high frequency partial discharge test technology for hydro-turbine generators, and existing research has shown that compared with low-frequency partial discharge test technology, ultra-high frequency partial discharge test technology can avoid some external interference, and the stability of test results is better than that of low-frequency partial discharge test technology.

[0003] However, due to the attenuation, reflection and resonance of partial discharge signals during propagation, signal distortion and distortion occur, especially for ultra-high frequency partial discharge signals, which are more seriously distorted and distorted, making the measured ultra-high frequency partial discharge signal mismatched with the actual partial discharge pulse, seriously affecting the accuracy of the test results. At the same time, the position dependence of partial discharge signals caused by frequency characteristics, the measurement differences caused by different detection equipment and methods, and the propagation characteristics of partial discharge signals at different locations all have a significant impact on the measurement of partial discharge signals. Figure 1 The schematic diagram shows a stator bar structure of a hydro-generator. Figure 1 As shown in the figure, when a partial discharge signal is injected into any point numbered 1 to 7, the response attenuation measured at the end of the stator bar is different. In actual production, partial discharge may occur at any position, and it is difficult to determine the specific partial discharge warning threshold. Because the partial discharge warning threshold is difficult to give, the current partial discharge test technology usually adopts a qualitative judgment method based on single-machine trend comparison, which cannot achieve quantitative analysis of partial discharge signals and requires high capabilities of on-site technicians. Summary of the invention

[0004] In view of this, the purpose of the embodiments of the present application is to provide a method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, a device for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, a machine-readable storage medium and a computer device, so as to overcome one or more defects existing in the partial discharge qualitative analysis method based on single-machine trend comparison in the prior art.

[0005] In order to achieve the above-mentioned purpose, a first aspect of an embodiment of the present application provides a method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, comprising:

[0006] Acquire the partial discharge test signal collected at the collection point and transmitted through the stator wire rod, analyze the collected partial discharge test signal to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point, and inject the partial discharge test signal from the injection point into the stator wire rod;

[0007] Obtaining the partial discharge signal collected at the collection point under actual working conditions;

[0008] If there are multiple injection points, the partial discharge signal is reconstructed using the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient, and the reconstructed partial discharge signal is corrected using the maximum value in the signal attenuation coefficient; if there is only one injection point, the partial discharge signal is corrected using the transfer function obtained by analysis, and the reconstructed partial discharge signal is corrected using the signal attenuation coefficient obtained by analysis;

[0009] Comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar;

[0010] When there are multiple injection points, after collecting the partial discharge test signal injected into the stator wire bar through the current injection point, the partial discharge test signal is injected again through the next injection point; the injection point is set in the suspended part of the head end of the stator wire bar.

[0011] In a specific embodiment of the present application, after analyzing the collected partial discharge test signal, the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point are obtained, including:

[0012] After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained;

[0013] determining a transfer function of the signal transmission path from the Smith chart;

[0014] The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain a signal attenuation coefficient of the signal transmission path.

[0015] In a specific embodiment of the present application, the collection point is located at a suspended portion at the end of the stator bar.

[0016] In a specific embodiment of the present application, reconstructing the partial discharge signal includes:

[0017] Discretizing the partial discharge signal, and converting the partial discharge pulse sequence obtained after discretization into the frequency domain;

[0018] When there are multiple injection points, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient is inversely Fourier transformed to obtain a reconstructed local discharge signal; or; when there is only one injection point, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function is inversely Fourier transformed to obtain a reconstructed local discharge signal.

[0019] In a specific embodiment of the present application, the signal attenuation coefficient is a ratio of the amplitude of the partial discharge test signal injected at the injection point to the amplitude of the partial discharge test signal collected at the collection point; the reconstructed partial discharge signal is corrected, including:

[0020] When there are multiple injection points, the product of the reconstructed local discharge signal and the maximum value of the signal attenuation coefficient is determined as the corrected local discharge signal; or; when there is only one injection point, the product of the reconstructed local discharge signal and the signal attenuation coefficient is determined as the corrected local discharge signal.

[0021] In a specific embodiment of the present application, comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude and determining whether a partial discharge event occurs in the stator bar includes:

[0022] If the amplitude of the corrected partial discharge signal is smaller than the preset typical partial discharge amplitude, it is determined that no partial discharge event occurs in the stator bar.

[0023] A second aspect of the embodiment of the present application provides a device for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, comprising:

[0024] An analysis module is used to obtain the partial discharge test signal collected at the collection point and transmitted through the stator wire rod, and to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point after analyzing the collected partial discharge test signal, wherein the partial discharge test signal is injected from the injection point to the stator wire rod;

[0025] An acquisition module, used to acquire the partial discharge signal collected at the collection point under actual working conditions;

[0026] A correction module, used to determine the number of injection points, if it is determined that the number of injection points is multiple, reconstruct the local discharge signal using the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient, and correct the reconstructed local discharge signal using the maximum value in the signal attenuation coefficient, if it is determined that the number of injection points is one, correct the local discharge signal using the transfer function obtained by analysis, and correct the reconstructed local discharge signal using the signal attenuation coefficient obtained by analysis;

[0027] An identification module, used for comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar;

[0028] When there are multiple injection points, after collecting the partial discharge test signal injected into the stator wire bar through the current injection point, the partial discharge test signal is injected again through the next injection point; the injection point is set in the suspended part of the head end of the stator wire bar.

[0029] In a specific embodiment of the present application, after analyzing the collected partial discharge test signal, the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point are obtained, including:

[0030] After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained;

[0031] determining a transfer function of the signal transmission path from the Smith chart;

[0032] The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain a signal attenuation coefficient of the signal transmission path.

[0033] A third aspect of an embodiment of the present application provides a machine-readable storage medium, on which instructions are stored. When the instructions are executed by a processor, the processor is configured to execute the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction as described in the first aspect of the embodiment of the present application.

[0034] The fourth aspect of an embodiment of the present application provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction described in the first aspect of an embodiment of the present application is implemented.

[0035] In the above technical solution, the transfer function of the partial discharge signal transmission path is determined by experimental means, and then the signal attenuation coefficient of the partial discharge signal transmission path is determined by comparing the partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point. After obtaining the partial discharge signal under actual working conditions, the partial discharge signal is corrected using the maximum signal attenuation coefficient and the corresponding transfer function. The amplitude of the corrected partial discharge signal can be considered as the partial discharge value used in this application to determine whether a partial discharge event occurs in the stator bar, which can be applied to the quantitative analysis of the partial discharge monitoring process. Compared with the qualitative analysis method based on single-machine trend comparison, the above embodiment is based on the technical concept of correcting the partial discharge signal with the maximum signal attenuation coefficient, and uses the corrected partial discharge signal to judge the partial discharge event, which reduces the ability requirements of the engineering site technicians and is more applicable.

[0036] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0038] Figure 1 The schematic diagram of the structure of the stator bar of the hydro-generator mentioned in the background technology is shown schematically;

[0039] Figure 2 A flow chart of a method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction according to an embodiment of the present application is schematically shown;

[0040] Figure 3 A schematic diagram of the process of the hydro-generator ultra-high frequency partial discharge identification method based on attenuation coefficient correction in a specific application example is shown;

[0041] Figure 4 The schematic diagram of the structure of the stator bar in a specific application example is shown;

[0042] Figure 5 The Smith chart schematically shows a specific application example in which the signal transmission path includes two wire rods;

[0043] Figure 6 The Smith chart schematically shows a specific application example when the signal transmission path includes four wire rods;

[0044] Figure 7 The Smith chart schematically shows a specific application example when the signal transmission path includes six wire rods;

[0045] Figure 8 The structural diagram of the ultra-high frequency partial discharge identification device of a hydro-turbine generator based on attenuation coefficient correction according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0047] Figure 2 The flowchart of the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction according to an embodiment of the present application is schematically shown. Figure 2 As shown, in one embodiment of the present application, a method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction may include the following steps:

[0048] Step 202, obtain the partial discharge test signal collected at the collection point after being transmitted through the stator wire rod, analyze the collected partial discharge test signal to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point, and inject the partial discharge test signal from the injection point into the stator wire rod. Wherein, when there are multiple injection points, after the partial discharge test signal injected into the stator wire rod through the current injection point is collected, the partial discharge test signal is injected again through the next injection point. The suspended part of the head end of the stator wire rod is provided with an injection point, that is: when there is one injection point, the injection point is located in the suspended part of the head end of the stator wire rod; when there are multiple injection points, the position of the injection point includes the suspended part of the head end of the stator wire rod.

[0049] As known, the stator bar is formed by one or more bars connected in series or in parallel, and the stator bar has a head end and an end end, and the head end of the stator bar includes a slot portion and a suspended portion.

[0050] In this application, the partial discharge test signal can be collected through a coupling device. The coupling device refers to a device for collecting partial discharge signals generated by stator bars in a partial discharge monitoring system. It is usually an active or passive four-terminal network that converts input current into output voltage signals. It can also be an ultra-high frequency partial discharge sensor, partial discharge antenna, etc. It should be understood that the location of the injection point needs to be determined in combination with the on-site conditions during specific applications. The location selection conditions that usually need to be considered are: whether the wiring conditions for the injection of partial discharge test signals are met, etc.

[0051] Step 204, obtaining a partial discharge signal collected at a collection point under actual working conditions.

[0052] Step 206, reconstruct and correct the partial discharge signal using the maximum signal attenuation coefficient and the corresponding transfer function. Specifically, if there are multiple injection points, the partial discharge signal is reconstructed using the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient, and the reconstructed partial discharge signal is corrected using the maximum value in the signal attenuation coefficient; if there is only one injection point, the partial discharge signal is corrected using the transfer function obtained by analysis, and the reconstructed partial discharge signal is corrected using the signal attenuation coefficient obtained by analysis.

[0053] Step 208, comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar.

[0054] As in the above embodiment, in the actual operating condition of the hydro-turbine generator, in order to correct the real-time partial discharge signal collected by one or more collection points, for each collection point, the transfer function and signal attenuation coefficient of the signal transmission path between the collection point and the injection point for injecting the partial discharge test signal into the stator wire rod are obtained by experimental means, and then the partial discharge signal collected by the collection point under the actual operating condition of the hydro-turbine generator is corrected by using the obtained maximum signal attenuation coefficient and the corresponding transfer function. It can be seen that when there is one injection point, because the signal transmission path between the suspended part of the stator wire rod head end and the collection point is the largest, under the traditional operating condition of the hydro-turbine generator, based on the principle that the signal transmission path is proportional to the signal attenuation intensity, the signal attenuation coefficient obtained by setting the injection point at the suspended part of the stator wire rod head end is the maximum signal attenuation coefficient. In order to adapt to the non-traditional operating conditions of the hydro-turbine generator, the above embodiment also proposes a scheme for determining the maximum signal attenuation coefficient based on multiple partial discharge test signal injection methods, that is, a multi-injection point test method, thereby improving the environmental applicability of the partial discharge identification method. Among them, the test process includes: injecting a partial discharge test signal at a selected injection point, and the partial discharge test signal can be simulated and generated by a signal generator or the like; after the injected partial discharge test signal is transmitted through the stator wire rod, it is collected at the collection point through a coupling device or the like. By correcting the real-time partial discharge signal with attenuation distortion, when performing ultra-high frequency partial discharge monitoring, on-site technicians can use the corrected partial discharge signal to quantitatively analyze the insulation condition of the stator wire rod. Compared with qualitative analysis, quantitative analysis requires lower operating ability of on-site technicians, and also makes the partial discharge monitoring method based on the above embodiment more applicable. It should be understood that the "correction" described in the above embodiment is based on the maximum signal attenuation coefficient. The purpose of the correction is to compare with the preset typical partial discharge amplitude to achieve quantitative analysis of the insulation condition of the stator wire rod, rather than the amplitude correction in the traditional sense to obtain accurate partial discharge signal amplitude.

[0055] In a specific embodiment of the present application, the collection point is located at a suspended portion at the end of the stator bar.

[0056] In a specific embodiment of the present application, in step 202, analyzing the collected partial discharge test signal to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point may include the following steps:

[0057] After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained;

[0058] Determine the transfer function of the signal transmission path between the injection point and the acquisition point from the Smith chart;

[0059] The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain the signal attenuation coefficient of the signal transmission path between the injection point and the collection point.

[0060] It should be understood that the specific parameters in the transfer function of the signal transmission path can be learned from the Smith chart, and the transfer function of the signal transmission path can be obtained through these specific parameters.

[0061] For example, the Smith original image can be obtained by analyzing the collected partial discharge test signal through a network analyzer. For example, the network analyzer can be a vector network analyzer.

[0062] In a specific embodiment of the present application, the signal attenuation coefficient is a ratio of the amplitude of the partial discharge test signal injected at the injection point to the amplitude of the partial discharge test signal collected at the collection point.

[0063] In a specific embodiment of the present application, when there are multiple injection points, reconstructing the collected partial discharge signal according to the transfer function of the signal transmission path corresponding to the maximum value of the signal attenuation coefficient includes the following steps:

[0064] Discretizing the collected partial discharge signal, and converting the partial discharge pulse sequence obtained after discretization into the frequency domain;

[0065] The ratio of the partial discharge pulse sequence converted to the frequency domain to the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient is inversely Fourier transformed to obtain a reconstructed partial discharge signal.

[0066] In a specific embodiment of the present application, when there is only one injection point, reconstructing the collected partial discharge signal according to the transfer function includes the following steps:

[0067] Discretizing the collected partial discharge signal, and converting the partial discharge pulse sequence obtained after discretization into the frequency domain;

[0068] The ratio of the partial discharge pulse sequence converted to the frequency domain to the transfer function is inversely Fourier transformed to obtain a reconstructed partial discharge signal.

[0069] For example, in a specific application, the reconstruction process is as follows:

[0070] SS1. Filter and reduce noise on the collected partial discharge signal.

[0071] SS2. After filtering and noise reduction, the collected partial discharge signal is sampled and discretized in the time domain to obtain a partial discharge pulse sequence, wherein the sampling frequency satisfies the Nyquist sampling theorem to avoid signal aliasing.

[0072] SS3. Use discrete Fourier transform to convert the discretized local discharge pulse sequence from the time domain to the frequency domain.

[0073] SS4. Perform inverse Fourier transform on the ratio of the local discharge pulse sequence converted to the frequency domain and the transfer function, and obtain the reconstructed local discharge signal after inverse Fourier transform.

[0074] Assuming that the time domain expression of the partial discharge signal emitted from the unknown partial discharge source in the stator bar is x(n), then the frequency domain expression of x(n) after discrete Fourier transform is:

[0075]

[0076] The time domain expression of the local discharge pulse sequence obtained after discretization is y(n), and the frequency domain expression of y(n) after discrete Fourier transform is:

[0077]

[0078] In equations 1 and 2, N represents the signal length, and k represents the index of the frequency component.

[0079] According to the discrete Fourier transform, the relationship between the partial discharge signal emitted from the unknown partial discharge source in the stator bar and the partial discharge pulse sequence obtained after discretization is as follows:

[0080] Y(k)=DFT{y(t)}=DFT{h(t)·x(n)} (Equation 3);

[0081] In Formula 3, DFT represents discrete Fourier transform, and h(t) represents the impulse response of the system consisting of all transmission media from the unknown partial discharge source in the stator bar to the acquisition point. The frequency domain expression of Formula 3 is as follows:

[0082] Y(k)=H(ω)×X(k) (Formula 4);

[0083] In Formula 4, H(w) represents the transfer function of the system. In this application, the system composed of all transmission media from the unknown partial discharge source in the stator bar to the collection point is a series combination of the stator bar, the connecting cable and the coupling device. Therefore, the transfer function of the system can also be expressed as:

[0084] H(ω)=H w (ω)×H c (ω)×H d (ω) (Formula 5);

[0085] In formula 5, H w (w), H c (w), H d(w) represent the transfer functions of stator bars, connecting cables and coupling devices respectively.

[0086] The ratio of the transfer function of the signal transmission path corresponding to the maximum value of the local discharge pulse sequence converted to the frequency domain and the obtained signal attenuation coefficient is determined as the frequency domain expression of the reconstructed local discharge signal, as shown in the following formula:

[0087]

[0088] The frequency domain expression of the reconstructed partial discharge signal is subjected to inverse Fourier transform to obtain the time domain expression of the partial discharge signal, as shown in the following formula:

[0089] x 1 (n) = IDFT[X 1 (k)] (Formula 7).

[0090] In a specific embodiment of the present application, the signal attenuation coefficient is the ratio of the amplitude of the partial discharge test signal injected at the injection point to the amplitude of the partial discharge test signal collected at the collection point. At this time, when there are multiple injection points, the collected partial discharge signal is corrected, which may include the following steps:

[0091] The product of the reconstructed partial discharge signal and the maximum value of the signal attenuation coefficient is determined as the corrected partial discharge signal.

[0092] When there is only one injection point, the collected partial discharge signal is corrected, which may include the following steps:

[0093] The product of the reconstructed partial discharge signal and the signal attenuation coefficient is determined as the corrected partial discharge signal.

[0094] In a specific embodiment of the present application, step 208, comparing the amplitude of the corrected partial discharge signal with the preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar, includes the following steps:

[0095] If the amplitude of the corrected partial discharge signal is smaller than the preset typical partial discharge amplitude, it is determined that no partial discharge event occurs in the stator bar.

[0096] In another embodiment of the present application, the periodic recurrence characteristic of the partial discharge signal can be combined, and the amplitudes of multiple corrected partial discharge signals can be compared with a preset typical partial discharge amplitude to determine whether a partial discharge event occurs in the stator bar. Compared with identifying partial discharge events using a single corrected partial discharge signal, the identification accuracy is improved.

[0097] In another embodiment of the present application, if the amplitude of the corrected partial discharge signal is greater than or equal to a preset typical partial discharge amplitude, it can be determined that a partial discharge event may have occurred in the stator bar. At this time, it can be combined with other partial discharge identification means to estimate the possible partial discharge source location on the stator winding and alert on-site technicians to perform troubleshooting.

[0098] Figure 3 The schematic diagram of the process of the ultra-high frequency partial discharge identification method of a hydro-turbine generator based on attenuation coefficient correction in a specific application example is shown schematically. In the specific application example, a vector network analyzer is used to analyze the Smith chart to determine the transfer function. The stator bar consists of six bars connected in series, such as Figure 4 The coupling device is arranged at the suspended part at the end of the sixth wire rod. Figure 3 As shown in FIG, the process of the ultra-high frequency partial discharge identification method of a hydro-turbine generator based on attenuation coefficient correction is as follows:

[0099] Step A1, select the injection point of the partial discharge test signal. Specifically, the attenuation degree of the ultra-high frequency partial discharge signal is usually positively correlated with the distance of the propagation path of the ultra-high frequency partial discharge signal in the stator wire rod of the hydro-turbine generator, that is, the greater the distance of the propagation path of the ultra-high frequency signal in the stator wire rod of the hydro-turbine generator, the more serious the attenuation and distortion of the ultra-high frequency signal collected at the signal acquisition end. Considering that many selected point positions do not meet the wiring conditions during the actual on-site test operation, this application example selects three injection points according to the on-site working conditions of the hydro-turbine generator. The injection points are respectively located at: the suspended part at the head end of the first wire rod, the suspended part at the head end of the third wire rod, and the suspended part at the head end of the fifth wire rod.

[0100] Step A2, transfer function test. Specifically, the vector network analyzer can test the transfer function of the stator bar, the transfer function of the connecting cable connecting the stator bar to the coupling device, and the transfer function of the coupling device respectively. The vector network analyzer can also be used to measure the transfer function of the entire system consisting of the stator bar, the connecting cable, and the coupling device. By changing the injection point position, the transfer function of the signal transmission path formed by the two bars, the connecting cable, and the coupling device is measured respectively. At this time, the Smith chart of the signal transmission path is as follows: Figure 5 As shown; the transfer function when four wire rods, connecting cables and coupling devices form a signal transmission path, the Smith chart of the signal transmission path at this time is as follows Figure 6 As shown; the transfer function when six wire rods, connecting cables and coupling devices form a signal transmission path, the Smith chart of the signal transmission path at this time is as follows Figure 7 shown.

[0101] Step A3, determine the maximum signal attenuation coefficient k max The signal attenuation coefficient is expressed as:

[0102]

[0103] In Formula 8, |x(t)| and |y(t)| represent the amplitude of the partial discharge test signal injected at the injection point and the amplitude of the partial discharge test signal collected by the coupling device, respectively.

[0104] Step A4, reconstructing and correcting the real-time partial discharge signal collected under actual working conditions using the maximum signal attenuation coefficient and the transfer function.

[0105] The frequency domain expression of the corrected real-time partial discharge signal is as follows:

[0106] X(k)=k max *Y(k) / H(w) (Formula 9);

[0107] The time domain continuous signal of the corrected real-time partial discharge signal is expressed as follows:

[0108] x(t)=k max *x 1 (t) (Formula 10);

[0109] In formula 10, x 1 (t) represents the time domain continuous signal of the reconstructed partial discharge signal.

[0110] Step A5, using the corrected partial discharge signal to determine whether a partial discharge event occurs in the stator bar. max x 1 (t)|<|x′(t)|, it is determined that no partial discharge event occurs in the stator bar at this time, and x′(t) represents the set typical partial discharge amplitude.

[0111] Figure 8 A schematic diagram of a hydro-generator ultra-high frequency partial discharge identification device based on attenuation coefficient correction according to an embodiment of the present application is shown. Figure 8 As shown, in one embodiment of the present application, a hydro-turbine generator ultra-high frequency partial discharge identification device 400 based on attenuation coefficient correction includes:

[0112] The analysis module 410 is used to obtain the partial discharge test signal collected at the collection point and transmitted through the stator wire rod, and to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point after analyzing the collected partial discharge test signal, wherein the partial discharge test signal is injected from the injection point to the stator wire rod;

[0113] An acquisition module 420 is used to acquire a partial discharge signal collected at a collection point under actual working conditions;

[0114] A correction module 430 is used to determine the number of injection points. If it is determined that there are multiple injection points, the partial discharge signal is reconstructed using the transfer function of the signal transmission path corresponding to the maximum value of the signal attenuation coefficient, and the reconstructed partial discharge signal is corrected using the maximum value of the signal attenuation coefficient. If it is determined that there are only one injection point, the partial discharge signal is corrected using the transfer function obtained by analysis, and the reconstructed partial discharge signal is corrected using the signal attenuation coefficient obtained by analysis.

[0115] An identification module 440 is used to compare the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determine whether a partial discharge event occurs in the stator bar;

[0116] When there are multiple injection points, after collecting the partial discharge test signal injected into the stator wire bar through the current injection point, the partial discharge test signal is injected again through the next injection point; the injection point is set in the suspended part of the head end of the stator wire bar.

[0117] In a specific embodiment, after analyzing the collected partial discharge test signal, the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point are obtained, including:

[0118] After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained;

[0119] determining a transfer function of the signal transmission path from the Smith chart;

[0120] The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain a signal attenuation coefficient of the signal transmission path.

[0121] In a specific embodiment, the collection point is located at a suspended portion at the end of the stator bar.

[0122] In a specific embodiment, reconstructing the partial discharge signal includes:

[0123] Discretizing the partial discharge signal, and converting the partial discharge pulse sequence obtained after discretization into the frequency domain;

[0124] When there are multiple injection points, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient is inversely Fourier transformed to obtain a reconstructed local discharge signal; or; when there is only one injection point, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function is inversely Fourier transformed to obtain a reconstructed local discharge signal.

[0125] In a specific embodiment, the signal attenuation coefficient is a ratio of the amplitude of the partial discharge test signal injected at the injection point to the amplitude of the partial discharge test signal collected at the collection point; the reconstructed partial discharge signal is corrected, including:

[0126] When there are multiple injection points, the product of the reconstructed local discharge signal and the maximum value of the signal attenuation coefficient is determined as the corrected local discharge signal; or; when there is only one injection point, the product of the reconstructed local discharge signal and the signal attenuation coefficient is determined as the corrected local discharge signal.

[0127] In a specific embodiment, comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude and determining whether a partial discharge event occurs in the stator bar includes:

[0128] If the amplitude of the corrected partial discharge signal is smaller than the preset typical partial discharge amplitude, it is determined that no partial discharge event occurs in the stator bar.

[0129] On the other hand, an embodiment of the present application also provides a processor, which implements the ultra-high frequency partial discharge identification method of a hydro-turbine generator based on attenuation coefficient correction as described in the above embodiment when executing at least one instruction, or at least one program, or a code set, or an instruction set.

[0130] On the other hand, an embodiment of the present application also provides a machine-readable storage medium, which stores instructions. When the instructions are executed by a processor, the processor is configured to execute the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction as described in the above embodiment.

[0131] Finally, an embodiment of the present application also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction described in the above embodiment is implemented.

[0132] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0133] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0134] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0136] In a typical configuration, an electronic device includes one or more processors (CPU), input / output interfaces, network interfaces, memory, and storage. The memory may include non-permanent memory in a machine-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a machine-readable medium.

[0137] Machine-readable media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0138] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0139] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, characterized in that: include: Acquire the partial discharge test signal collected at the collection point and transmitted through the stator wire rod, analyze the collected partial discharge test signal to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point, and inject the partial discharge test signal from the injection point into the stator wire rod; Obtaining the partial discharge signal collected at the collection point under actual working conditions; If there are multiple injection points, the partial discharge signal is reconstructed using the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient, and the reconstructed partial discharge signal is corrected using the maximum value in the signal attenuation coefficient; if there is only one injection point, the partial discharge signal is corrected using the transfer function obtained by analysis, and the reconstructed partial discharge signal is corrected using the signal attenuation coefficient obtained by analysis; Comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar; When there are multiple injection points, after collecting the partial discharge test signal injected into the stator wire bar through the current injection point, the partial discharge test signal is injected again through the next injection point; the injection point is set in the suspended part of the head end of the stator wire bar.

2. The method according to claim 1, characterized in that After analyzing the collected partial discharge test signal, the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point are obtained, including: After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained; determining a transfer function of the signal transmission path from the Smith chart; The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain a signal attenuation coefficient of the signal transmission path.

3. The method according to claim 1, characterized in that The collection point is located at the suspended part at the end of the stator bar.

4. The method according to claim 2, characterized in that: Reconstructing the partial discharge signal includes: Discretizing the partial discharge signal, and converting the partial discharge pulse sequence obtained after discretization into the frequency domain; When there are multiple injection points, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient is inversely Fourier transformed to obtain a reconstructed local discharge signal; or; when there is only one injection point, the ratio of the local discharge pulse sequence converted to the frequency domain to the transfer function is inversely Fourier transformed to obtain a reconstructed local discharge signal.

5. The method according to claim 1, characterized in that The signal attenuation coefficient is the ratio of the amplitude of the partial discharge test signal injected at the injection point to the amplitude of the partial discharge test signal collected at the collection point; Correct the reconstructed partial discharge signal, including: When there are multiple injection points, the product of the reconstructed local discharge signal and the maximum value of the signal attenuation coefficient is determined as the corrected local discharge signal; or; when there is only one injection point, the product of the reconstructed local discharge signal and the signal attenuation coefficient is determined as the corrected local discharge signal.

6. The method according to claim 1, characterized in that The comparing the amplitude of the corrected partial discharge signal with the preset typical partial discharge amplitude and determining whether a partial discharge event occurs in the stator bar includes: If the amplitude of the corrected partial discharge signal is smaller than the preset typical partial discharge amplitude, it is determined that no partial discharge event occurs in the stator bar.

7. A device for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction, characterized in that: include: An analysis module is used to obtain the partial discharge test signal collected at the collection point and transmitted through the stator wire rod, and to obtain the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point after analyzing the collected partial discharge test signal, wherein the partial discharge test signal is injected from the injection point to the stator wire rod; An acquisition module, used to acquire the partial discharge signal collected at the collection point under actual working conditions; A correction module, used to determine the number of injection points, if it is determined that the number of injection points is multiple, reconstruct the local discharge signal using the transfer function of the signal transmission path corresponding to the maximum value in the signal attenuation coefficient, and correct the reconstructed local discharge signal using the maximum value in the signal attenuation coefficient, if it is determined that the number of injection points is one, correct the local discharge signal using the transfer function obtained by analysis, and correct the reconstructed local discharge signal using the signal attenuation coefficient obtained by analysis; An identification module, used for comparing the amplitude of the corrected partial discharge signal with a preset typical partial discharge amplitude, and determining whether a partial discharge event occurs in the stator bar; When there are multiple injection points, after collecting the partial discharge test signal injected into the stator wire bar through the current injection point, the partial discharge test signal is injected again through the next injection point; the injection point is set in the suspended part of the head end of the stator wire bar.

8. The device according to claim 7, characterized in that After analyzing the collected partial discharge test signal, the transfer function and signal attenuation coefficient of the signal transmission path between the injection point and the collection point are obtained, including: After analyzing the collected partial discharge test signal, a Smith chart of the signal transmission path between the injection point and the collection point is obtained; determining a transfer function of the signal transmission path from the Smith chart; The partial discharge test signal injected at the injection point and the partial discharge test signal collected at the collection point are compared to obtain a signal attenuation coefficient of the signal transmission path.

9. A machine-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor is configured to execute the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction according to any one of claims 1 to 6.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for identifying ultra-high frequency partial discharge of a hydro-turbine generator based on attenuation coefficient correction according to any one of claims 1 to 6 is implemented.

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