A method for inverting discharge current pulse width based on electromagnetic wave signals

Abstract

The present invention discloses a method for inverting the pulse width of a discharge current based on an electromagnetic wave signal, and relates to the field of pulse current characteristic inversion. The method comprises: S1, establishing a simulation model of partial discharge in a gas-insulated switchgear GIS, performing streamer simulation on the gas-insulated switchgear GIS, and establishing a partial discharge excitation source model based on the signal obtained by the streamer simulation; S2, setting an excitation source and four probes, starting timing when the excitation source radiates electromagnetic waves outward, and recording the voltage signal waveform received by the probe; S3, processing and analyzing the received signal to obtain the pulse width of the pulse current, and analyzing the inverted pulse current characteristic according to the pulse width of the pulse current. According to the measured pulse width, combined with the definition and characteristics of the pulse current, analyzing its key parameters such as amplitude and frequency is helpful to understand the dynamic characteristics of the pulse current.

Description

Technical Field

[0001] The invention relates to the field of pulse current characteristic inversion, in particular to a discharge current pulse width inversion method based on electromagnetic wave signals. Background Art

[0002] When there are insulation defects inside power and electrical equipment, discharge will occur, which will seriously affect the safety and reliability of the equipment. The discharge inside the equipment will generate an equivalent pulse current. By analyzing the pulse current width, the size of the discharge can be indirectly calculated, so as to accurately diagnose the severity of the insulation defect and provide maintenance suggestions for equipment operation and maintenance personnel. However, since the discharge point is often located inside the equipment, there is currently no direct method to detect this equivalent pulse current.

[0003] Along with the current pulse, an electromagnetic wave signal is also generated. The electromagnetic wave radiation propagates to the outside of the device. By detecting this electromagnetic wave signal, it can be determined whether there is a discharge phenomenon inside and the discharge source can be located. The present invention utilizes this characteristic and combines simulation analysis with time difference positioning to propose a discharge current pulse width inversion method based on electromagnetic wave signals.

[0004] The arrival time difference method can well locate the local discharge point in the gas insulated switchgear (GIS). The energy accumulation method is used to determine the starting time of the signal. The energy accumulation function remains unchanged after reaching a certain value. This inflection point can be used as a mark to determine the end time of the signal. The point when the value of the energy accumulation function reaches 0.5% of the maximum value is taken as the inflection point of the starting time of the signal. The horizontal axis at this time is regarded as the sum of the starting time of the signal and the time required for propagation. Due to the intense refraction and reflection in the GIS, there will be a certain tailing phenomenon in the received signal. Therefore, the energy function will have a slow rising process at the end. The noise reduction and smoothing algorithm is used to reduce the fluctuation of the tail of the received signal. The moment when the signal reaches 99% of the maximum value of the energy accumulation function is taken as the inflection point of the end time of the signal.

[0005] According to the TDOA algorithm, the position coordinates of the local discharge source can be obtained, the distance between the source point and the reference sensor can be calculated, and the energy accumulation function of the reference sensor can be used to obtain the start and end times of the received signal. By subtracting the time required for signal propagation, the start and end times of the source signal can be estimated, and the pulse width can be estimated by taking the difference between the start and end times. Summary of the invention

[0006] To solve the above problems, the present application provides a discharge current pulse width inversion method based on electromagnetic wave signals, which studies the pulse current characteristics through the pulse current width, further analyzes the fault causes of the electrical system, optimizes system performance or performs fault prediction, etc.

[0007] In the present application, a discharge current pulse width inversion method based on an electromagnetic wave signal is provided, comprising the following steps:

[0008] S1. Establish a simulation model of partial discharge in a gas-insulated switchgear GIS, perform streamer simulation on the gas-insulated switchgear GIS, and establish a partial discharge excitation source model based on the signal obtained by the streamer simulation;

[0009] S2, setting an excitation source and four probes, starting timing when the excitation source radiates electromagnetic waves, and recording the voltage signal waveform received by the probes;

[0010] S3. Process and analyze the received signal to obtain the pulse width of the pulse current, and analyze the inversion pulse current characteristics according to the pulse width of the pulse current.

[0011] Preferably, the specific contents of establishing the simulation model of partial discharge occurring in the gas insulated switchgear GIS in S1 are:

[0012] Obtain the actual structural parameters of GIS, analyze and process the parameters to extract GIS characteristic factors;

[0013] There are several modeling modules preset, and the current modeling module is determined according to the characteristic factors;

[0014] Create a 3D model based on the actual structural parameters of GIS and set the corresponding material properties of the 3D model;

[0015] Define the boundary conditions and excitation sources of the 3D model and perform meshing to ensure a balance between simulation accuracy and computational efficiency;

[0016] Run the simulation and observe and record the propagation characteristics of the electromagnetic waves in each structure.

[0017] Preferably, the 3D model includes a straight-tube structure, an insulator-type structure, an L-type structure and a T-type structure;

[0018] The material properties include dielectric constant and magnetic permeability, and the material properties are used to simulate the real internal environment of GIS.

[0019] Preferably, the specific content of establishing the local discharge excitation source model based on the signal obtained by streamer simulation in S1 is:

[0020] Acquiring characteristic parameters of a partial discharge signal, wherein the characteristic parameters include a pulse current and a voltage waveform;

[0021] Analyze the characteristic parameters and extract the time domain features and frequency domain features in the characteristic parameters;

[0022] According to the time domain characteristics and frequency domain characteristics, the type of excitation source is determined, and the excitation source type matching the characteristics of the streamer simulation signal is selected;

[0023] According to the excitation source type and characteristic parameters, a partial discharge excitation source model is constructed;

[0024] The local discharge excitation source model is verified by comparing the local discharge signal generated by the excitation source model with the streamer simulation signal.

[0025] Preferably, the specific content of the pulse width of the pulse current obtained by processing and analyzing the received signal is:

[0026] The received signal is subjected to noise reduction and smoothing, and the arrival time difference of each sensor is obtained by energy accumulation method;

[0027] The excitation source position is solved according to the TDOA algorithm, the propagation time of the signal between the source point and the sensor is calculated, the start and end times of the estimated signal are obtained, and the pulse width of the pulse current is calculated.

[0028] To summarize, the discharge current pulse width inversion method based on electromagnetic wave signals of the present invention, compared with the traditional pulse current characteristic inversion technology, estimates the pulse width of the pulse current, combines the definition and characteristics of the pulse current, analyzes its key parameters such as amplitude and frequency, and studies the dynamic characteristics of the pulse current according to the pulse width of the pulse current to further analyze the cause of the fault of the electrical system, optimize the system performance or perform fault prediction.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The excitation source is obtained by calculating the streamer discharge of the discharge current pulse width inversion method based on the electromagnetic wave signal of the present invention;

[0031] Figure 2 The waveform of a received signal after noise reduction in a discharge current pulse width inversion method based on an electromagnetic wave signal of the present invention;

[0032] Figure 3 It is a cumulative energy function image of a discharge current pulse width inversion method based on electromagnetic wave signals of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below by means of the accompanying drawings and embodiments. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​described in these embodiments do not limit the scope of the present application.

[0034] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0035] Technologies, systems, and devices known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, systems, and devices should be considered part of the specification.

[0036] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0037] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0038] The present invention provides a discharge current pulse width inversion method based on electromagnetic wave signals, which is specifically as follows: S1, establishing a simulation model of partial discharge occurring in a gas-insulated switchgear GIS, performing streamer simulation on the gas-insulated switchgear GIS, and establishing a partial discharge excitation source model based on a signal obtained by the streamer simulation;

[0039] S2, setting an excitation source and four probes, starting timing when the excitation source radiates electromagnetic waves, and recording the voltage signal waveform received by the probes;

[0040] S3. Process and analyze the received signal to obtain the pulse width of the pulse current, and analyze the inversion pulse current characteristics according to the pulse width of the pulse current.

[0041] Preferably, the specific contents of establishing the simulation model of partial discharge occurring in the gas insulated switchgear GIS in S1 are:

[0042] Obtain the actual structural parameters of GIS, analyze and process the parameters to extract GIS characteristic factors;

[0043] There are several modeling modules preset, and the current modeling module is determined according to the characteristic factors;

[0044] Create a 3D model based on the actual structural parameters of GIS and set the corresponding material properties of the 3D model;

[0045] Define the boundary conditions and excitation sources of the 3D model and perform meshing to ensure a balance between simulation accuracy and computational efficiency;

[0046] Run the simulation and observe and record the propagation characteristics of the electromagnetic waves in each structure.

[0047] Preferably, the 3D model includes a straight-tube structure, an insulator-type structure, an L-type structure and a T-type structure;

[0048] The material properties include dielectric constant and magnetic permeability, and the material properties are used to simulate the real internal environment of GIS.

[0049] Preferably, the specific content of establishing the local discharge excitation source model based on the signal obtained by streamer simulation in S1 is:

[0050] Acquiring characteristic parameters of a partial discharge signal, wherein the characteristic parameters include a pulse current and a voltage waveform;

[0051] Analyze the characteristic parameters and extract the time domain features and frequency domain features in the characteristic parameters;

[0052] According to the time domain characteristics and frequency domain characteristics, the type of excitation source is determined, and the excitation source type matching the characteristics of the streamer simulation signal is selected;

[0053] According to the excitation source type and characteristic parameters, a partial discharge excitation source model is constructed;

[0054] The local discharge excitation source model is verified by comparing the local discharge signal generated by the excitation source model with the streamer simulation signal.

[0055] Preferably, the specific content of the pulse width of the pulse current obtained by processing and analyzing the received signal is:

[0056] The received signal is subjected to noise reduction and smoothing, and the arrival time difference of each sensor is obtained by energy accumulation method;

[0057] The excitation source position is solved according to the TDOA algorithm, the propagation time of the signal between the source point and the sensor is calculated, the start and end times of the estimated signal are obtained, and the pulse width of the pulse current is calculated.

[0058] XFDTD7.3.0 was used as the electromagnetic field simulation software to conduct a simulation experiment on the pulse width of the UHF signal. The numerical results of the streamer discharge were used as the excitation source. Figure 1 As shown, the unit of streamer discharge is ampere (A). The signal obtained by the probe at (98.7, -0.8, 0) is smoothed as follows: Figure 2 shown.

[0059] By comparing the peak moments of the waveform, it is found that the smoothed signal has a phase shift of 0.006us compared to the original signal. The function image obtained by the energy accumulation method for the smoothed received signal is as follows: Figure 3 As shown:

[0060] In this way, the start and end time of the signal can be estimated, and the pulse width of the signal can be estimated accordingly. The coordinates of the source point obtained by the TDOA algorithm can be used to obtain the relative distance between the excitation source and the simulation source, and the propagation time of the electromagnetic wave is 0.0036us. The smooth operation causes a phase shift of 0.006us. The arrival time of the signal of sensor 1 is 0.0207412us, and the end time of the signal is 0.0634755us. Therefore, the estimated value of the start time is 0.0111412us, and the relative error with the actual start time of the excitation source is 0.0129223us is 14%; the estimated value of the end time is 0.0538755us, and the actual end time is 0.0566002us, with a relative error of 5%. At the same time, the pulse width of the pulse current is 0.045459us, and the actual pulse width is 0.0436779us, with a relative error of 4%. It can be seen that this method can better estimate the start and end time of the signal and the pulse width, so as to indirectly calculate the size of the discharge and then determine the severity of the discharge.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A discharge current pulse width inversion method based on electromagnetic wave signals, characterized in that: The following steps are involved: S1. Establish a simulation model of partial discharge in a gas-insulated switchgear GIS, perform streamer simulation on the gas-insulated switchgear GIS, and establish a partial discharge excitation source model based on the signal obtained by the streamer simulation; S2, setting an excitation source and four probes, starting timing when the excitation source radiates electromagnetic waves, and recording the voltage signal waveform received by the probes; S3, processing and analyzing the received signal to obtain the pulse width of the pulse current, and analyzing the inversion pulse current characteristics according to the pulse width of the pulse current; The specific contents of the simulation model of partial discharge in gas-insulated switchgear GIS established in S1 are: Obtain the actual structural parameters of GIS, analyze and process the parameters to extract GIS characteristic factors; There are several modeling modules preset, and the current modeling module is determined according to the characteristic factors; Create a 3D model based on the actual structural parameters of GIS and set the corresponding material properties of the 3D model; Define the boundary conditions and excitation sources of the 3D model and perform meshing to ensure a balance between simulation accuracy and computational efficiency; Run simulations to observe and record the propagation characteristics of electromagnetic waves in each structure; The specific content of the pulse width of the pulse current obtained by processing and analyzing the received signal in S3 is: The received signal is subjected to noise reduction and smoothing, and the arrival time difference of each sensor is obtained by energy accumulation method; The excitation source position is solved according to the TDOA algorithm, the propagation time of the signal between the source point and the sensor is calculated, the start and end time of the estimated signal are obtained, and the pulse width of the pulse current is calculated; The specific contents of establishing the partial discharge excitation source model based on the signal obtained by streamer simulation in S1 are as follows: Acquiring characteristic parameters of a partial discharge signal, wherein the characteristic parameters include a pulse current and a voltage waveform; Analyze the characteristic parameters and extract the time domain features and frequency domain features in the characteristic parameters; According to the time domain characteristics and frequency domain characteristics, the type of excitation source is determined, and the excitation source type matching the characteristics of the streamer simulation signal is selected; According to the excitation source type and characteristic parameters, a partial discharge excitation source model is constructed; The local discharge excitation source model is verified by comparing the local discharge signal generated by the excitation source model with the streamer simulation signal.

2. A discharge current pulse width inversion method based on electromagnetic wave signals according to claim 1, characterized in that: The 3D model includes a straight tube structure, an insulator structure, an L-shaped structure and a T-shaped structure; The material properties include dielectric constant and magnetic permeability, and the material properties are used to simulate the real internal environment of GIS.

3. The method for inverting the discharge current pulse width based on electromagnetic wave signals according to claim 1, characterized in that: The specific positions of the excitation source and four probes in S2 are: The initial position of the excitation source is preset, and a three-dimensional coordinate system is established with the position of the excitation source as the origin; The coordinate unit is centimeters; The position coordinates of the four probes are: (98.7, -0.8, 0), (98.7, 4, 7.5), (98.7, 12.5, 35) and (98.7, 12.5, -20).

Images