Porcelain insulator zero value detection device and detection method thereof

Abstract

The invention belongs to the technical field of porcelain insulator zero-value detection, and discloses a porcelain insulator zero-value detection device and a detection method thereof, and the device is used for portable rapid zero-value detection or zero-value detection for early defective insulators / partially degraded insulators. The portable rapid zero value detection device comprises an impulse voltage generator, an insulator unit and a measurement module, the output end of the impulse voltage generator is connected with the input end of the insulator unit, and the output end of the insulator unit is connected with the measurement module; the device for detecting the zero value of the early defective insulator / the partially degraded insulator comprises an impulse voltage generator, a Rogowski coil, an integrator and an oscilloscope, the Rogowski coil is arranged on a wire to be detected in a surrounding mode, the output end of the Rogowski coil is connected into the integrator, and the output end of the integrator is connected with the oscilloscope. The invention provides a porcelain insulator zero value detection method taking a high-frequency component as a criterion, and the method can achieve the quick and reliable detection of whether the value of the insulator is zero or not.

Description

Technical Field

[0001] The present invention relates to the technical field of porcelain insulator zero value detection, and in particular to a porcelain insulator zero value detection device and a detection method thereof. Background Art

[0002] Electricity plays the role of the energy lifeline in modern industrial production and social development. The power transmission network, centered around ultra-high / ultra-high voltage transmission lines, leverages its technological advantages of low loss, large capacity, and long-distance transmission to undertake important functions such as cross-regional energy allocation and clean energy consumption. In this complex system, porcelain insulator strings, the core insulating components connecting conductors to towers, must withstand long-term mechanical tensions of up to hundreds of tons, kilovolt-level electromagnetic field stress, and complex environmental erosion such as lightning strikes, industrial pollution, salt spray corrosion, and extreme temperature and humidity cycles. Zero-value defects (insulation resistance approaching zero) caused by performance degradation can lead to major accidents such as flashover tripping, string breakage, and tower collapse.

[0003] Currently, researchers have proposed a variety of methods for detecting zero-value defects in insulators. These include manual observation, ultrasonic testing, ultraviolet imaging, leakage current measurement, and Doppler detection. Manual observation, while simple and intuitive, relies on on-site inspection by inspectors. However, this method requires significant manpower and material resources, is subject to geographical limitations, and can produce significant discrepancies in results depending on the observation angle. Ultrasonic testing uses ultrasonic waves with frequencies greater than 20 kHz to inspect insulators, but its application range is short, limiting its use to experimental testing at insulator manufacturers and preventing it from being used for on-line defect detection. Ultraviolet imaging uses ultraviolet light from insulators to detect and image them, but it has drawbacks such as requiring nighttime testing and data acquisition during partial discharge. Leakage current measurement uses the insulator's electrical characteristics to determine if an insulator is faulty, but the data required is easily affected by the insulator's shape, number of insulators, and weather, leading to unstable test results. Doppler detection uses the Doppler effect in physics to detect insulator defects, but is difficult to operate, expensive, unsuitable for large-scale online testing, and difficult to implement when obstructed by obstacles. These methods all have drawbacks, necessitating the development of more effective and convenient technologies for accurately detecting zero-value defects in insulators.

[0004] In view of the shortcomings of the existing methods, the present invention proposes a porcelain insulator zero value detection method based on high-frequency components, which can realize rapid and reliable detection of whether the insulator is zero value, making up for the shortcomings of the above methods. Summary of the Invention

[0005] The embodiment of the present invention provides a porcelain insulator zero value detection device and a detection method thereof to solve the above-mentioned technical problems in the prior art.

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, the following is a brief summary. This summary is not intended to be a comprehensive review, identify key or essential elements, or delineate the scope of these embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a porcelain insulator zero value detection device is provided.

[0008] In one embodiment, the porcelain insulator zero value detection device is used for portable rapid zero value detection, comprising an impulse voltage generator, an insulator unit, and a measurement module, wherein the output end of the impulse voltage generator is connected to the input end of the insulator unit, and the output end of the insulator unit is connected to the measurement module;

[0009] Wherein, the impulse voltage generator is used to generate an impulse high voltage of a predetermined value on the secondary side of the transformer;

[0010] The insulator unit is used to rectify the impulse high-voltage signal using a diode, and apply the rectified impulse high-voltage signal to the porcelain insulator to be tested;

[0011] The measuring module is used to obtain the current signal of the porcelain insulator to be detected, and to determine whether the insulator is a zero-value insulator by analyzing the high-frequency signal in the current signal.

[0012] In one embodiment, the impulse voltage generator includes a voltage module, a capacitor C1, a switch S1, a resistor R1, a diode D1 and a pulse transformer T1;

[0013] Among them, the voltage module is connected in parallel at both ends of the capacitor C1, one end of the capacitor C1 is connected to the switch S1, the resistor R1 and the positive electrode of the diode D1 in sequence, and the negative electrode of the diode D1 and the other end of the capacitor C1 are respectively connected to the input end of the pulse transformer T1.

[0014] In one embodiment, the insulator unit includes an insulator to be detected and a diode D2;

[0015] Among them, one end of the insulator to be detected and the positive electrode of the diode D2 are respectively connected to the output end of the pulse transformer T1, and the other end of the insulator to be detected and the negative electrode of the diode D2 are both connected to the input end of the measurement module.

[0016] In one embodiment, the measurement module includes a pulse transformer T2, a resistor R2, a variable capacitor VD1, a variable capacitor VD2, a switch S2, a capacitor C2, a capacitor C0, and an inductor L;

[0017] The input end of the pulse transformer T2 is respectively connected to the other end of the insulator to be detected and the cathode of the diode D2, and the output end of the pulse transformer T2 is respectively connected to one end of the resistor R2, one end of the capacitor C2, one end of the inductor L, and one end of the capacitor C0;

[0018] The other end of the resistor R2 is respectively connected to the positive electrode of the variable capacitor VD1, the positive electrode of the variable capacitor VD2, the other end of the inductor L and the other end of the capacitor C0;

[0019] The other end of the capacitor C2 is connected to the negative electrode of the variable capacitor VD1 and the other end of the switch S2 respectively, and the other end of the switch S2 is connected to the negative electrode of the variable capacitor VD2.

[0020] In one embodiment, the shell of the measurement module is a double-layer structure, with high-conductivity aluminum as the outer layer material and high-magnetic-permeability Permalloy as the inner layer material to shield external electromagnetic interference. It is connected to the insulator to be detected through a pulse transformer with a transformation ratio of 1 to achieve isolation and prevent high-voltage crosstalk.

[0021] In one embodiment, the capacitance of the variable capacitor VD1 is controlled by changing the DC voltage Vc, and the capacitance can be increased by closing the switch S2.

[0022] In one embodiment, the equivalent capacitance of the capacitor C2 and the variable capacitor is determined by the DC voltage Vc and the switch S2.

[0023] In one embodiment, the variable capacitor VD1 , the variable capacitor VD2 , the capacitor C2 , and the inductor L1 together form a voltage-controlled high-pass filter.

[0024] In one embodiment, controlling the DC voltage value Vc and the switch S2 can achieve screening of current components in different frequency bands, and the component sizes of the insulator current signal at different frequencies can be obtained from the maximum voltage value of the capacitor C0.

[0025] According to a second aspect of an embodiment of the present invention, a method for detecting a zero value of a porcelain insulator is provided.

[0026] In one embodiment, the porcelain insulator zero value detection method includes:

[0027] The voltage module is used to charge the capacitor C1. When the voltage of the capacitor C1 reaches a predetermined voltage value, the switch S1 is closed and the voltage module is turned off, so that the secondary side of the pulse transformer T1 generates a high voltage surge.

[0028] The impact high voltage signal is rectified by diode D2, and the rectified impact high voltage signal is applied to the porcelain insulator to be tested;

[0029] The measurement module is used to obtain the current signal on the porcelain insulator to be detected, and the zero value detection of the insulator is achieved by analyzing the magnitude of the high-frequency signal in the current signal.

[0030] In one embodiment, the predetermined voltage value is 190-230V, and the impulse voltage is 40-70kV.

[0031] According to a third aspect of an embodiment of the present invention, a porcelain insulator zero value detection device is provided.

[0032] In one embodiment, a porcelain insulator zero-value detection device is used for zero-value detection of early defective insulators / partially degraded insulators, and includes an impulse voltage generator, a Rogowski coil, an integrator, and an oscilloscope, wherein the output end wire of the impulse voltage generator is connected to the insulator, the Rogowski coil is arranged around the output end wire of the impulse voltage generator, the output end of the Rogowski coil is connected to the integrator, and the output of the integrator is connected to the oscilloscope.

[0033] In one embodiment, when the Rogowski coil is placed around the conductor to be measured, the Rogowski coil needs to be closed to ensure uniform winding.

[0034] In one embodiment, the integrator integrates the voltage signal to obtain an output signal consistent with the original current waveform.

[0035] According to a fourth aspect of an embodiment of the present invention, a method for detecting a zero value of a porcelain insulator is provided.

[0036] In one embodiment, the porcelain insulator zero value detection method includes:

[0037] Wrap the Rogowski coil around the wire to be tested, connect the output end of the Rogowski coil to the integrator, and connect the output end of the integrator to the oscilloscope;

[0038] Use an oscilloscope to collect time-domain current signals and record the number of sampling points, discrete sampling signal, sampling frequency, maximum absolute value of the signal, and normalized signal amplitude;

[0039] The time domain current signal is decomposed into several frequency bands using wavelet packet decomposition to determine the frequency range and the boundary between low frequency and high frequency. The Daubechies 4th order wavelet is used as the wavelet basis function to determine the wavelet packet decomposition coefficients and time coordinates.

[0040] Based on the intensity of discrete sampling signals in a specific frequency band and a specific position, the node energy and total energy corresponding to the node are calculated;

[0041] Determine the sum of high-frequency energy and high-energy energy according to the preset number of nodes, and calculate the high-frequency energy ratio through the sum of high-frequency energy and high-energy energy;

[0042] According to the comparison result of the high-frequency energy ratio and the preset high-frequency energy ratio threshold, the zero-value insulator and the normal insulator are determined to realize the zero-value detection of the porcelain insulator.

[0043] In one embodiment, the normalization formula is:

[0044]

[0045] Where x norm [m] represents the normalized signal amplitude, x[m] represents the discrete sampling signal of the mth sampling point, N represents the number of sampling points, x[i] represents the discrete sampling signal of the ith sampling point, and max(|x[m]|) represents the maximum absolute value of the signal.

[0046] In one embodiment, the number of decomposition layers of wavelet packet decomposition is 7 and the number of frequency bands is 2. j , where j represents the number of decomposition levels.

[0047] In one embodiment, the frequency range corresponding to the nth node of the jth layer of wavelet packet decomposition is Where, F s Indicates the sampling frequency;

[0048] The frequency range of 95-105kHz is used as the boundary between low frequency and high frequency.

[0049] In one embodiment, the formula for wavelet packet decomposition coefficients is:

[0050]

[0051] Where C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, x norm [m] represents the normalized signal amplitude, N represents the number of sampling points, ψ j,n,k [m] represents the wavelet packet function, k represents the translation parameter, and j represents the number of decomposition layers.

[0052] In one embodiment, the formula for the time coordinate is:

[0053]

[0054] Where, t k represents time, that is, the position of the signal on the time axis; k represents the translation parameter, and its value is Fs represents the sampling frequency; j represents the number of decomposition layers.

[0055] In one embodiment, the formula for node energy is:

[0056]

[0057] The formula for the total energy of a node is:

[0058]

[0059] Where E(n) represents the node energy of the nth node, N represents the number of sampling points, k represents the translation parameter, j represents the number of decomposition layers, and C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, E total Represents the total energy of the node.

[0060] In one embodiment, when n>21, E(n) is regarded as high-frequency energy, and the formula for the high-frequency energy ratio is:

[0061]

[0062] Where HF Ratio Indicates the high-frequency energy ratio, E n＞21 Represents the sum of high-frequency energy, E total Represents the total energy of the node.

[0063] In one embodiment, determining the zero-value insulator and the normal insulator based on the comparison result of the high-frequency energy ratio and the preset high-frequency energy ratio threshold to achieve zero-value detection of the porcelain insulator includes:

[0064] When the high-frequency energy ratio is greater than 50%, the porcelain insulator is judged as a zero-value insulator;

[0065] When the high-frequency energy ratio is less than 10%, the porcelain insulator is judged as a normal insulator.

[0066] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0067] 1) This invention introduces high-frequency components as criterion signals to improve identification accuracy. Conventional methods often rely on low-frequency or static features such as DC resistance, leakage current, or infrared images. This invention, for the first time, uses high-frequency voltage / current components as a basis for zero-value discrimination, significantly improving the sensitivity and accuracy of identifying zero-value insulators. Experimental verification shows that the high-frequency response exhibits significant differences among zero-value insulators, providing a new dimension for rapid and accurate identification.

[0068] 2) The non-contact detection method of the present invention has the potential for online detection. Compared with traditional contact or power outage detection methods, the voltage excitation method of the present invention has non-contact characteristics (which can be expanded to apply impulse signals online), providing a theoretical basis and technical path for live detection of transmission lines, greatly reducing operation and maintenance costs and operational risks.

[0069] 3) The circuit structure of the present invention is simple, which facilitates engineering implementation and integrated development. The proposed detection circuit consists only of an impulse voltage source, a high-pass filter and a detection module. It has a simple structure and low implementation cost. It is particularly suitable for deployment in insulator detection robots, drone systems or handheld terminals, and has broad engineering application prospects.

[0070] 4) The present invention is adaptable to complex power grid environments and has strong robustness. This method uses signal frequency characteristics as the core criterion and is less affected by external environmental factors such as weather, humidity, and pollution level. It has strong adaptability and can be stably applied to a variety of complex field conditions.

[0071] 5) The present invention has intelligent diagnostic capabilities and scalability. High-frequency response data can be introduced into machine learning models as training sets to achieve intelligent classification and prediction of zero-value defects, providing a technical basis for building a smart grid perception system.

[0072] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0074] Figure 1 is a circuit diagram of a porcelain insulator zero value detection device according to an exemplary embodiment;

[0075] Figure 2 is a flow chart showing a method for detecting a zero value of a porcelain insulator according to another exemplary embodiment;

[0076] Figure 3 is a circuit diagram of a porcelain insulator zero value detection device according to yet another exemplary embodiment;

[0077] Figure 4 is a flow chart of a method for detecting a zero value of a porcelain insulator according to yet another exemplary embodiment;

[0078] Figure 5 It is a schematic diagram of the voltage change process at both ends of the insulator after the impulse voltage is applied;

[0079] Figure 6It is a schematic diagram of voltage and current waveforms of zero-value insulators;

[0080] Figure 7 It is a schematic diagram of the voltage and current waveform of a normal insulator;

[0081] Figure 8 It is the spectrum diagram of normal insulator and defective insulator. DETAILED DESCRIPTION

[0082] The following description and accompanying drawings sufficiently illustrate the specific embodiments herein to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims, including all available equivalents thereof. Herein, the terms "first," "second," and the like are used solely to distinguish one element from another and do not require or imply any actual relationship or order between these elements. In practice, the first element can also be referred to as the second element, and vice versa. Furthermore, the terms "comprise," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a structure, device, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such structure, device, or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the structure, device, or apparatus comprising the element. The various embodiments herein are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Similar or identical parts between the various embodiments can be referenced to each other.

[0083] The terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used herein to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are intended only to facilitate the description of this document and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In the description herein, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, they can be mechanical or electrical connections, or they can be internal connections between two elements, they can be directly connected, or they can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0084] As used herein, unless otherwise specified, the term "plurality" means two or more.

[0085] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0086] In this article, the term "and / or" is used to describe the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0087] It should be understood that, although the various steps in the flowchart are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps may be performed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily performed at the same time, but may be performed at different times. The execution order of these sub-steps or stages is not necessarily to be performed in sequence, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0088] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software so that the processor can call and execute the operations corresponding to the above modules.

[0089] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0090] Figure 1 An embodiment of a porcelain insulator zero value detection device of the present invention is shown.

[0091] In this optional embodiment, the porcelain insulator zero-value detection device is used for portable rapid zero-value detection, comprising an impulse voltage generator, an insulator unit, and a measurement module, wherein the output end of the impulse voltage generator is connected to the input end of the insulator unit, and the output end of the insulator unit is connected to the measurement module;

[0092] Wherein, the impulse voltage generator is used to generate an impulse high voltage of a predetermined value on the secondary side of the transformer;

[0093] The insulator unit is used to rectify the impulse high-voltage signal using a diode, and apply the rectified impulse high-voltage signal to the porcelain insulator to be tested;

[0094] The measuring module is used to obtain the current signal of the porcelain insulator to be detected, and to determine whether the insulator is a zero-value insulator by analyzing the high-frequency signal in the current signal.

[0095] In this optional embodiment, the impulse voltage generator includes a voltage module, a capacitor C1, a switch S1, a resistor R1, a diode D1 and a pulse transformer T1;

[0096] Among them, the voltage module is connected in parallel at both ends of the capacitor C1, one end of the capacitor C1 is connected to the switch S1, the resistor R1 and the positive electrode of the diode D1 in sequence, and the negative electrode of the diode D1 and the other end of the capacitor C1 are respectively connected to the input end of the pulse transformer T1.

[0097] In this optional embodiment, the insulator unit includes an insulator to be detected and a diode D2;

[0098] Among them, one end of the insulator to be detected and the positive electrode of the diode D2 are respectively connected to the output end of the pulse transformer T1, and the other end of the insulator to be detected and the negative electrode of the diode D2 are both connected to the input end of the measurement module.

[0099] In this optional embodiment, the measurement module includes a pulse transformer T2, a resistor R2, a variable capacitor VD1, a variable capacitor VD2, a switch S2, a capacitor C2, a capacitor C0, and an inductor L;

[0100] The input end of the pulse transformer T2 is respectively connected to the other end of the insulator to be detected and the cathode of the diode D2, and the output end of the pulse transformer T2 is respectively connected to one end of the resistor R2, one end of the capacitor C2, one end of the inductor L, and one end of the capacitor C0;

[0101] The other end of the resistor R2 is respectively connected to the positive electrode of the variable capacitor VD1, the positive electrode of the variable capacitor VD2, the other end of the inductor L and the other end of the capacitor C0;

[0102] The other end of the capacitor C2 is connected to the negative electrode of the variable capacitor VD1 and the other end of the switch S2 respectively, and the other end of the switch S2 is connected to the negative electrode of the variable capacitor VD2.

[0103] In this optional embodiment, the shell of the measuring module is a double-layer structure, with high-conductivity aluminum as the outer layer material and high-magnetic-permeability Permalloy as the inner layer material to shield external electromagnetic interference. It is connected to the insulator to be detected through a pulse transformer with a transformation ratio of 1 to achieve isolation and prevent high-voltage crosstalk.

[0104] In this optional embodiment, the capacitance of the variable capacitor VD1 is controlled by changing the DC voltage Vc, and the capacitance can be increased by closing the switch S2.

[0105] In this optional embodiment, the equivalent capacitance of the capacitor C2 and the variable capacitor is determined by the DC voltage Vc and the switch S2.

[0106] In this optional embodiment, the variable capacitor VD1 , the variable capacitor VD2 , the capacitor C2 , and the inductor L1 together form a voltage-controlled high-pass filter.

[0107] In this optional embodiment, controlling the DC voltage value Vc and the switch S2 can achieve screening of current components in different frequency bands, and the component sizes of the insulator current signal at different frequencies can be obtained from the maximum voltage value of the capacitor C0.

[0108] Figure 2 An embodiment of a porcelain insulator zero value detection method of the present invention is shown.

[0109] In this optional embodiment, the porcelain insulator zero value detection method includes:

[0110] Step S101: Use the voltage module to charge the capacitor C1. When the voltage of the capacitor C1 reaches a predetermined voltage value, close the switch S1 and turn off the voltage module to generate a surge high voltage on the secondary side of the pulse transformer T1.

[0111] Step S102: rectifying the impulse high-voltage signal through the diode D2, and applying the rectified impulse high-voltage signal to the porcelain insulator to be tested;

[0112] Step S103: using the measurement module to obtain the current signal on the porcelain insulator to be detected, and realizing zero value detection of the insulator by analyzing the magnitude of the high frequency signal in the current signal.

[0113] In this optional embodiment, the predetermined voltage value is 190-230V, and the impulse voltage is 40-70kV.

[0114] Figure 3 An embodiment of a porcelain insulator zero value detection device of the present invention is shown.

[0115] In this optional embodiment, the porcelain insulator zero value detection device is used for zero value detection of early defective insulators / partially degraded insulators, and includes an impulse voltage generator, a Rogowski coil, an integrator and an oscilloscope, wherein the output end wire of the impulse voltage generator is connected to the insulator, the Rogowski coil is arranged around the output end wire of the impulse voltage generator, the output end of the Rogowski coil is connected to the integrator, and the output of the integrator is connected to the oscilloscope.

[0116] In this optional embodiment, during the process of placing the Rogowski coil around the conductor to be measured, the Rogowski coil needs to be closed to ensure uniform winding.

[0117] In this optional embodiment, the integrator integrates the voltage signal to obtain an output signal consistent with the original current waveform.

[0118] Figure 4 An embodiment of a porcelain insulator zero value detection method of the present invention is shown.

[0119] In this optional embodiment, the porcelain insulator zero value detection method includes:

[0120] Step 201: Wrap a Rogowski coil around the conductor to be tested, connect the output end of the Rogowski coil to an integrator, and connect the output end of the integrator to an oscilloscope;

[0121] Step 202: Use an oscilloscope to collect the time domain current signal and record the number of sampling points, discrete sampling signal, sampling frequency, maximum absolute value of the signal, and normalized signal amplitude;

[0122] Step 203: Decompose the time-domain current signal into several frequency bands using wavelet packet decomposition to determine the frequency range and the boundary between low frequency and high frequency; and use Daubechies 4th-order wavelet as the wavelet basis function to determine the wavelet packet decomposition coefficients and time coordinates;

[0123] Step 204: Calculate the node energy and total energy corresponding to the node based on the intensity of the discrete sampling signal in the specific frequency band and specific position;

[0124] Step 205: Determine the sum of high-frequency energy and high-energy energy according to the preset number of nodes, and calculate the high-frequency energy ratio by the sum of high-frequency energy and high-energy energy;

[0125] Step 206: Determine the zero-value insulator and the normal insulator based on the comparison result of the high-frequency energy ratio and the preset high-frequency energy ratio threshold, thereby realizing the zero-value detection of the porcelain insulator.

[0126] In this optional embodiment, the normalization formula is:

[0127]

[0128] Where x norm [m] represents the normalized signal amplitude, x[m] represents the discrete sampling signal of the mth sampling point, N represents the number of sampling points, x[i] represents the discrete sampling signal of the ith sampling point, and max(|x[m]|) represents the maximum absolute value of the signal.

[0129] In this optional embodiment, the number of decomposition layers of wavelet packet decomposition is 7 and the number of frequency bands is 2. j , where j represents the number of decomposition levels.

[0130] In this optional embodiment, the frequency range corresponding to the nth node of the jth layer of wavelet packet decomposition is Where, F s Indicates the sampling frequency;

[0131] Among them, when n=0, the frequency range is 0-4.6875kHz, and when n=107, the frequency range is 501.5625-506.25kHz. When n=21, the frequency range is 98.4375-103.125kHz as the boundary between low frequency and high frequency. When n>21, it is the high frequency range, and when n≤21, it is the low frequency range.

[0132] In this optional embodiment, the formula for wavelet packet decomposition coefficients is:

[0133]

[0134] Where C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, x norm [m] represents the normalized signal amplitude, N represents the number of sampling points, ψ j,n,k [m] represents the wavelet packet function, k represents the translation parameter, and j represents the number of decomposition layers.

[0135] In this optional embodiment, the formula for the time coordinate is

[0136]

[0137] Where, t k represents time, that is, the position of the signal on the time axis; k represents the translation parameter, and its value is F s represents the sampling frequency; j represents the number of decomposition layers.

[0138] In this optional embodiment, the formula for node energy is:

[0139]

[0140] The formula for the total energy of a node is:

[0141]

[0142] Where E(n) represents the node energy of the nth node, N represents the number of sampling points, k represents the translation parameter, j represents the number of decomposition layers, and C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, E total Represents the total energy of the node.

[0143] In this optional embodiment, when n>21, E(n) is regarded as high-frequency energy, and the formula for the high-frequency energy ratio is:

[0144]

[0145] Where HF Ratio Indicates the high-frequency energy ratio, E n＞21 Represents the sum of high-frequency energy, E total Represents the total energy of the node.

[0146] In this optional embodiment, determining the zero-value insulator and the normal insulator based on the comparison result of the high-frequency energy ratio and the preset high-frequency energy ratio threshold to implement the zero-value detection of the porcelain insulator includes:

[0147] When the high-frequency energy ratio is greater than 50%, the porcelain insulator is judged as a zero-value insulator;

[0148] When the high-frequency energy ratio is less than 10%, the porcelain insulator is judged as a normal insulator.

[0149] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are further explained from the perspective of architecture and principle as follows:

[0150] Currently, in actual operation, there is a lack of effective detection methods to accurately determine whether porcelain insulators are at zero value. The loss of strings and lines caused by zero-value insulators in China can seriously affect the safe operation of power systems. Therefore, it is necessary to explore more reliable and rapid methods for detecting the zero value of porcelain insulators.

[0151] The present invention proposes a porcelain insulator zero-value detection method based on high-frequency components. The method uses a pulse transformer to increase the voltage generated by the short-circuit of a capacitor with an original voltage of 200V to 40kV and then rectifies it through a diode to generate a high voltage of 50-60kV on the insulator. The characteristics of the high-frequency component of the current on the insulator are obtained to determine whether the insulator is zero-valued.

[0152] The present invention proposes a porcelain insulator zero-value detection method based on high-frequency components. The method aims to quickly and intuitively detect and judge zero-value insulators from the perspective of the insulator's electrical characteristics, thereby providing a criterion for the replacement of porcelain insulators and preventing string and line drop accidents of zero-value insulators.

[0153] After sufficient experiments, it was found that after applying a 50-60kV impulse voltage to the insulator, there was a significant difference in the voltage change process between the normal insulator and the insulator with internal defects. The typical change process is as follows: Figure 5 shown.

[0154] Under the same impulse voltage, zero-value insulators will be repeatedly broken down during the pressurization process due to internal crack defects. This process is accompanied by a rapid drop in voltage, and a high-frequency current with a peak value of up to 1800mA will be generated on the insulator. This can be used as a criterion to distinguish normal insulators from insulators with internal defects, and quickly realize the zero-value detection of insulators.

[0155] For normal insulators, under the same impulse voltage, there are no crack defects inside the insulator. During the pressurization process, the voltage rises to the maximum value at a rate of 1.0kV / s-1.3kV / s and is further maintained for more than 100ms. Due to the large capacitance of the insulator itself (50-110pF), the peak value of the charging current is only +130mA, and it rises smoothly and gradually decays.

[0156] In addition to being simple to implement, this method has another great advantage in that it is less affected by the contamination of the insulator surface. Even if the equivalent salt density on the insulator surface reaches 0.25 mg / cm 2 , the insulation resistance under dry conditions is less than 100k ohms. If the internal insulation of the insulator is intact and has no defects, the rise time of the charging current will still be between 1.0kV / s-1.3kV / s, and will not lead to an increase in its high-frequency discharge component. Therefore, compared with other insulator zero detection methods, this method is less affected by the environment and is not prone to misjudgment.

[0157] The present invention proposes two specific implementation methods, which can be selected according to equipment conditions and accuracy requirements during specific operations.

[0158] Method 1 (rapid detection, can be used with portable rapid zero detection equipment):

[0159] Typical zero-value insulator voltage and current waveforms are as follows: Figure 6 , the typical normal insulator voltage and current waveform is as follows Figure 7 , it can be seen that the high-frequency component in the current signal of the zero-value insulator is very obvious compared with that of the normal insulator (as shown in Table 1).

[0160] Table 1 Time domain characteristics of insulators under impulse voltage

[0161]

[0162] In order to judge whether the insulator has high frequency components under impulse voltage, the circuit design of the device of the present invention is as follows: Figure 1 shown. Figure 1 This is the overall circuit connection diagram after the insulator under test is connected to the impulse voltage generator and the measurement module (to the right of T2).

[0163] To improve detection accuracy, the measurement module housing designed in this invention uses a double-layer structure, with high-conductivity aluminum as the outer layer material and high-magnetic permeability Permalloy as the inner layer material to shield external electromagnetic interference. It is connected to the insulator through a transformer with a transformation ratio of 1 to achieve isolation and prevent high-voltage crosstalk. Figure 1 VD1 is a variable capacitor, whose capacitance is controlled by varying the DC voltage Vc. To meet the 0-500kHz frequency measurement range, VD2 is connected in parallel. Switch S2 is closed when a higher capacitance is required. In the actual circuit, the capacitance of C2 is much larger than that of VD1. The equivalent capacitance of the variable capacitor and C2 is determined by Vc and S2. The variable capacitor, along with the fixed capacitor C2 and inductor L1, forms a voltage-controlled high-pass filter. Controlling Vc and S2 allows current components in different frequency bands to be filtered. The maximum voltage on capacitor C0 is measured to determine the magnitude of the insulator current signal at different frequencies.

[0164] The advantage of this circuit is that it has a simple structure. It can generate the impulse voltage required for zero detection and measure the current components in different frequency bands to realize the zero value detection of insulators.

[0165] The specific detection method of the above device is as follows:

[0166] The first step is to connect the circuit and connect the porcelain insulator to be tested to the output port circuit of the impulse voltage generator.

[0167] The second step is to turn on the DC power supply to charge the capacitor.

[0168] The third step is to increase the capacitor voltage to 200V and close Figure 1 The middle switch S1 turns off the DC power supply. At this time, the capacitor is connected to the pulse transformer T1, generating an impact high voltage of about 60kV on the secondary side of the transformer.

[0169] In the fourth step, the impulse high-voltage signal acts on the porcelain insulator after being rectified by the diode, and the current signal on the porcelain insulator is obtained by the measurement module.

[0170] The fifth step is to determine whether the insulator is a zero-value insulator by analyzing the high-frequency signal in the current signal.

[0171] Method 2 (simple circuit, reliable results, targeted at early defective insulators / partially degraded insulators):

[0172] In addition to judging the insulator zero value from the amplitude characteristics after filtering, it can also be judged directly from the spectrum characteristics of the discharge current of the insulator to be tested. As shown in Table 2, the discharge current of the defective insulator has obvious high-frequency components, and the spectrum has prominent components in the range of tens to hundreds of kHz. The main frequency of the normal insulator is generally smooth, such as Figure 8 shown.

[0173] Table 2 Frequency domain characteristics of insulator current under impulse voltage

[0174]

[0175] The measurement module here uses Rogowski coil and integrator. Figure 3 For a specific circuit, by integrating the voltage signal with the integrator, an output signal V consistent with the waveform of the original current I can be obtained. out .

[0176] Early defective insulators are difficult to identify under conventional power frequency, but the method of judging the high-frequency component of the insulator voltage / current under impulse voltage in the present invention can effectively detect such insulator defects.

[0177] Taking oscilloscope measurement as an example, the insulator is zeroed according to the steps in the technical solution. The specific analysis method of connecting the measurement module to the circuit and analyzing the signal is as follows:

[0178] (1) Wrap the Rogowski coil around the conductor to be measured (the coil must be closed to ensure uniform winding), connect the coil output to the integrator, and connect the integrator output to the oscilloscope;

[0179] (2) The time domain current signal collected by the oscilloscope, the number of sampling points is recorded as N, the discrete sampling signal is recorded as x[m] (m is 0, 1, ..., N-1), and the sampling frequency is F s (Take 1.2MHz as an example), max(|x[m]|) is the maximum absolute value of the signal, and the signal amplitude is normalized and recorded as x norm (m), the normalized formula is:

[0180]

[0181] Where x norm [m] represents the normalized signal amplitude, x[m] represents the discrete sampling signal of the mth sampling point, N represents the number of sampling points, x[i] represents the discrete sampling signal of the ith sampling point, and max(|x[m]|) represents the maximum absolute value of the signal.

[0182] (3) Using wavelet packet decomposition, set the decomposition layer j = 7, and decompose the signal into 2 j frequency bands, each with a bandwidth of 4.6875kHz. The frequency range corresponding to the nth node in the jth layer of wavelet packet decomposition is n=0 represents a frequency range of 0-4.6875 kHz, and n=107 represents a frequency range of about 500 kHz. n=21 (frequency range of about 100 kHz) is taken as the boundary between low frequency and high frequency.

[0183] (4) Using Daubechies 4th order (db4) wavelet as the wavelet basis function, the wavelet packet decomposition coefficient is:

[0184]

[0185] Where C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, x norm [m] represents the normalized signal amplitude, N represents the number of sampling points, ψ j,n,k [m] represents the wavelet packet function, which is directly determined by db4, and k represents the translation parameter, which represents the position of the discrete signal x[m] on the time axis (k is ), j represents the number of decomposition layers.

[0186] Its specific time coordinates are:

[0187]

[0188] Where, t k represents time, that is, the position of the signal on the time axis; k represents the translation parameter, and its value is F s represents the sampling frequency; j represents the number of decomposition layers.

[0189] (5) The node energy corresponding to the nth node is:

[0190]

[0191] The total energy is:

[0192]

[0193] Where E(n) represents the node energy of the nth node, N represents the number of sampling points, k represents the translation parameter, j represents the number of decomposition layers, and C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, E total Represents the total energy of the node.

[0194] (6) When n>21, E(n) is regarded as high-frequency energy, denoted by E n＞21 is the sum of high frequency energy, and the final high frequency energy ratio HF Ratio for:

[0195]

[0196] Where HF Ratio Indicates the high-frequency energy ratio, E n＞21 Represents the sum of high-frequency energy, E totalrepresents the total energy of the node;

[0197] Calculate the high frequency energy ratio HF Ratio When the value is greater than 50%, it is a zero-value insulator; when it is less than 10%, it is a normal insulator.

[0198] The present invention is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A porcelain insulator zero value detection device for portable rapid zero value detection, characterized in that: It includes an impulse voltage generator, an insulator unit and a measuring module, wherein the output end of the impulse voltage generator is connected to the input end of the insulator unit, and the output end of the insulator unit is connected to the measuring module; Wherein, the impulse voltage generator is used to generate an impulse high voltage of a predetermined value on the secondary side of the transformer; The insulator unit is used to rectify the impulse high-voltage signal using a diode, and apply the rectified impulse high-voltage signal to the porcelain insulator to be tested; The measuring module is used to obtain the current signal of the porcelain insulator to be detected, and to determine whether the insulator is a zero-value insulator by analyzing the high-frequency signal in the current signal.

2. A porcelain insulator zero value detection device according to claim 1, characterized in that: The impulse voltage generator includes a voltage module, a capacitor C1, a switch S1, a resistor R1, a diode D1 and a pulse transformer T1; Among them, the voltage module is connected in parallel at both ends of the capacitor C1, one end of the capacitor C1 is connected to the switch S1, the resistor R1 and the positive electrode of the diode D1 in sequence, and the negative electrode of the diode D1 and the other end of the capacitor C1 are respectively connected to the input end of the pulse transformer T1.

3. A porcelain insulator zero value detection device according to claim 2, characterized in that: The insulator unit includes an insulator to be detected and a diode D2; Among them, one end of the insulator to be detected and the positive electrode of the diode D2 are respectively connected to the output end of the pulse transformer T1, and the other end of the insulator to be detected and the negative electrode of the diode D2 are both connected to the input end of the measurement module.

4. A porcelain insulator zero value detection device according to claim 3, characterized in that: The measuring module includes a pulse transformer T2, a resistor R2, a variable capacitor VD1, a variable capacitor VD2, a switch S2, a capacitor C2, a capacitor C0 and an inductor L; The input end of the pulse transformer T2 is respectively connected to the other end of the insulator to be detected and the cathode of the diode D2, and the output end of the pulse transformer T2 is respectively connected to one end of the resistor R2, one end of the capacitor C2, one end of the inductor L, and one end of the capacitor C0; The other end of the resistor R2 is respectively connected to the positive electrode of the variable capacitor VD1, the positive electrode of the variable capacitor VD2, the other end of the inductor L and the other end of the capacitor C0; The other end of the capacitor C2 is connected to the negative electrode of the variable capacitor VD1 and the other end of the switch S2 respectively, and the other end of the switch S2 is connected to the negative electrode of the variable capacitor VD2.

5. The porcelain insulator zero value detection device according to claim 1, characterized in that: The shell of the measurement module is a double-layer structure, with high-conductivity aluminum as the outer layer material and high-magnetic permeability Permalloy as the inner layer material to shield external electromagnetic interference. It is connected to the insulator to be tested through a pulse transformer with a transformation ratio of 1 to achieve isolation and prevent high-voltage crosstalk.

6. The porcelain insulator zero value detection device according to claim 4, characterized in that: The capacitance of the variable capacitor VD1 is controlled by changing the DC voltage Vc, and the capacitance can be increased by closing the switch S2.

7. The porcelain insulator zero value detection device according to claim 4, characterized in that: The equivalent capacitance of the capacitor C2 and the variable capacitor is determined by the DC voltage Vc and the switch S2.

8. The porcelain insulator zero value detection device according to claim 4, characterized in that: The variable capacitor VD1 , the variable capacitor VD2 , the capacitor C2 , and the inductor L1 together form a voltage-controlled high-pass filter.

9. The porcelain insulator zero value detection device according to claim 4, characterized in that: By controlling the DC voltage value Vc and the switch S2 , current components of different frequency bands can be screened, and the component sizes of the insulator current signal at different frequencies can be obtained from the maximum voltage value of the capacitor C0 .

10. A method for detecting zero value of a porcelain insulator, characterized in that: include: The voltage module is used to charge the capacitor C1. When the voltage of the capacitor C1 reaches a predetermined voltage value, the switch S1 is closed and the voltage module is turned off, so that the secondary side of the pulse transformer T1 generates a high voltage surge. The impact high voltage signal is rectified by diode D2, and the rectified impact high voltage signal is applied to the porcelain insulator to be tested; The measurement module is used to obtain the current signal on the porcelain insulator to be detected, and the zero value detection of the insulator is achieved by analyzing the magnitude of the high-frequency signal in the current signal.

11. A porcelain insulator zero value detection method according to claim 10, characterized in that: The predetermined voltage value is 190-230V, and the impulse voltage is 40-70kV.

12. A porcelain insulator zero value detection device for zero value detection of early defective insulators / partially degraded insulators, characterized in that: The device comprises an impulse voltage generator, a Rogowski coil, an integrator and an oscilloscope, wherein the output wire of the impulse voltage generator is connected to an insulator, the Rogowski coil is arranged around the output wire of the impulse voltage generator, the output end of the Rogowski coil is connected to the integrator, and the output of the integrator is connected to the oscilloscope.

13. The porcelain insulator zero value detection device according to claim 12, characterized in that: When placing the Rogowski coil around the conductor to be measured, the Rogowski coil needs to be closed to ensure uniform winding.

14. The porcelain insulator zero value detection device according to claim 1, characterized in that: By integrating the voltage signal with the integrator, an output signal consistent with the original current waveform can be obtained.

15. A method for detecting zero value of a porcelain insulator, characterized in that: include: Wrap the Rogowski coil around the wire to be tested, connect the output end of the Rogowski coil to the integrator, and connect the output end of the integrator to the oscilloscope; Use an oscilloscope to collect time-domain current signals and record the number of sampling points, discrete sampling signal, sampling frequency, maximum absolute value of the signal, and normalized signal amplitude; The time-domain current signal is decomposed into several frequency bands using wavelet packet decomposition to determine the frequency range and the boundary between low and high frequencies. The Daubechies 4th-order wavelet is used as the wavelet basis function to determine the wavelet packet decomposition coefficients and time coordinates. Based on the intensity of discrete sampling signals in a specific frequency band and a specific position, the node energy and total energy corresponding to the node are calculated; Determine the sum of high-frequency energy and high-energy energy according to the preset number of nodes, and calculate the high-frequency energy ratio through the sum of high-frequency energy and high-energy energy; According to the comparison result of the high-frequency energy ratio and the preset high-frequency energy ratio threshold, the zero-value insulator and the normal insulator are determined to realize the zero-value detection of the porcelain insulator.

16. A porcelain insulator zero value detection method according to claim 15, characterized in that: The normalization formula is: Where x norm [m] represents the normalized signal amplitude, x[m] represents the discrete sampling signal of the mth sampling point, N represents the number of sampling points, x[i] represents the discrete sampling signal of the ith sampling point, and max(|x[m]|) represents the maximum absolute value of the signal.

17. A porcelain insulator zero value detection method according to claim 15, characterized in that: The number of decomposition layers of wavelet packet decomposition is 7 and the number of frequency bands is 2. j , where j represents the number of decomposition levels.

18. A porcelain insulator zero value detection method according to claim 15, characterized in that: The frequency range corresponding to the nth node in the jth layer of wavelet packet decomposition is Where, F s Indicates the sampling frequency; The frequency range of 95-105kHz is used as the boundary between low frequency and high frequency.

19. A porcelain insulator zero value detection method according to claim 15, characterized in that: The formula for wavelet packet decomposition coefficients is: Where C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, x norm [m] represents the normalized signal amplitude, N represents the number of sampling points, ψ j,n,k [m] represents the wavelet packet function, k represents the translation parameter, and j represents the number of decomposition layers.

20. The method for detecting zero value of a porcelain insulator according to claim 15, characterized in that: The formula for the time coordinate is Where, t k represents time, that is, the position of the signal on the time axis; k represents the translation parameter; F s represents the sampling frequency; j represents the number of decomposition layers.

21. A porcelain insulator zero value detection method according to claim 15, characterized in that: The formula for node energy is: The formula for the total energy of a node is: Where E(n) represents the node energy of the nth node, N represents the number of sampling points, k represents the translation parameter, j represents the number of decomposition layers, and C j,n (k) represents the intensity of the discrete sampling signal x[m] in a specific frequency band and a specific position, E total Represents the total energy of the node.

22. A porcelain insulator zero value detection method according to claim 15, characterized in that: When n>21, E(n) is regarded as high-frequency energy, and the formula for the high-frequency energy ratio is: Where HF Ratio Indicates the high-frequency energy ratio, E n＞21 Represents the sum of high-frequency energy, E total Represents the total energy of the node.

23. A porcelain insulator zero value detection method according to claim 15, characterized in that: The method of determining a zero-value insulator and a normal insulator based on a comparison result of the high-frequency energy ratio and a preset high-frequency energy ratio threshold, and realizing zero-value detection of porcelain insulators, comprises: When the high-frequency energy ratio is greater than 50%, the porcelain insulator is judged as a zero-value insulator; When the high-frequency energy ratio is less than 10%, the porcelain insulator is judged as a normal insulator.

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