CN111537936A - High-frequency partial discharge signal reconstruction method and system - Google Patents

Abstract

The present application discloses a high-frequency partial discharge signal reconstruction method and system. The method includes the programmable pulse sequence generating device outputting a voltage waveform U ₁ , and transmitting it through high-frequency coupling to generate a current I ₁ ; the high-frequency current sensor receives the current I ₀ generated by the partial discharge, and converts the partial discharge current I through its own transmission impedance. ₀ is converted into a voltage waveform U ₀ that can be stored by an oscilloscope; the voltage waveform U ₁ output by the programmable pulse sequence generating device is the same as the partial discharge current I ₀ , and the current I ₁ and the current I ₀ have the same waveform, thereby realizing the high-frequency pulse current. Waveform reconstruction. By using the high-frequency partial discharge signal reconstruction method and system provided in the present application, the typical partial discharge signal in the real scene of the substation can be completely reproduced.

Description

A kind of high frequency partial discharge signal reconstruction method and system

technical field

The present application relates to the field of electrical equipment partial discharge information processing, and in particular, to a high-frequency partial discharge signal reconstruction method and system.

Background technique

Partial discharge detection is the most important technical means in the current operating state detection technology of electrical equipment, and the function of partial discharge detection instruments is the primary prerequisite for network access detection. At present, the calibration of high-frequency partial discharge detection instruments at home and abroad mainly focuses on the performance assessment of high-frequency sensors, including the transmission impedance, sensitivity, linearity and other indicators of the sensor, and the calibration of the pattern recognition function of high-frequency partial discharge detection instruments Experimental studies have not yet been reported.

The verification of the pattern recognition function of the high-frequency partial discharge detection instrument is mainly realized in two ways: one is to go to the substation for on-site measurement, but the on-site partial discharge environment is complex and changeable, the actual measurement has many uncertainties, and the test is time-consuming and labor-intensive. Another method is to design a typical defect model of partial discharge, and generate partial discharge signal by means of pressure, but this method is not stable, mainly reflected in that the signal amplitude cannot be adjusted, the discharge continuity cannot be guaranteed, and the discharge type switching is troublesome and many more.

Therefore, a high-frequency-based partial discharge signal reconstruction method is urgently needed, which can completely reproduce the typical partial discharge signal of the real scene of the substation.

SUMMARY OF THE INVENTION

In order to achieve the above purpose, the application provides the following technical solutions:

A high-frequency partial discharge signal reconstruction method, comprising:

The programmable pulse sequence generating device outputs the voltage waveform U1, which is emitted through high-frequency coupling to generate the current I1;

The high-frequency current sensor receives the current I0 generated by the partial discharge, and converts the partial discharge current I0 into the voltage waveform U0 that the oscilloscope can store through its own transmission impedance;

The voltage waveform U1 output by the programmable pulse sequence generating device is the same as the partial discharge current I0, and the current I1 and the current I0 have the same waveform, thereby realizing the waveform reconstruction of the high-frequency pulse current.

The above-mentioned high-frequency partial discharge signal reconstruction method, wherein, the current generated by the partial discharge source partial discharge is I0, the current I0 flows through the high-frequency current sensor, and the high-frequency current sensor is used as a receiving device, and its transmission impedance is Z ( jω), which is converted into a voltage waveform U0 that can be stored by an oscilloscope through a high-frequency current sensor.

In the above-mentioned high-frequency partial discharge signal reconstruction method, the relationship between the signal input I0 and U0 is as follows:

U _o (jw)=I ₀ (jw)Z(jw)

Among them, Z(jω) is the transmission impedance of the high-frequency current sensor.

The above-mentioned high-frequency partial discharge signal reconstruction method, wherein, the relationship between the signal source output signal waveform U1 and U0 is:

U ₁ (jw)=U ₀ (jw)/Z(jw)=I ₀ (jw)

Therefore, U1 has the same waveform as the original pulse current I0, and U1 outputs the current I1 through a 50Ω resistor, and I1 has the same waveform as I0.

The present application also provides a high-frequency partial discharge signal reconstruction system, including: a programmable pulse sequence generating device, a power divider, a high-frequency current sensor, an oscilloscope, and a broadband impedance matching unit;

The calibration signal output by the programmable pulse sequence generator is connected to an RF power divider with a characteristic impedance of 50Ω through a high-frequency coaxial feeder, and the calibration signal is divided into two outputs, one of which is connected to the oscilloscope with a high-frequency coaxial line for Observe the output of the programmable pulse sequence generator, and the other is connected to the broadband impedance matching unit for calibrating the high-frequency current sensor with a high-frequency coaxial line; the characteristic impedance of the coaxial transmission line is all 50Ω.

In the above-mentioned high-frequency partial discharge signal reconstruction system, the high-frequency coupling tool is used to install the calibrated high-frequency current sensor, which is a transmission line structure deformed by an RF coaxial line with a characteristic impedance of 50Ω.

In the above-mentioned high-frequency partial discharge signal reconstruction system, an interference signal loop is added to the high-frequency coupling tooling to simulate the high-frequency interference signal in the substation environment.

In the above-mentioned high-frequency partial discharge signal reconstruction system, the high-frequency coupling tool adopts a coaxial cavity with 50Ω wave impedance, and the injection capacitor C0 adopts a high-frequency ceramic capacitor of 100pF±2%.

The above-mentioned high-frequency partial discharge signal reconstruction system, wherein the high-frequency current sensor is clamped in the middle of the matching unit, the size of the core wire of the matching unit and the shell satisfies the characteristic impedance of 50Ω, and the size of the shell is determined by the input and output terminals. The center transition forms a tapered transition structure to meet the broadband matching requirements. The output end of the matching unit is connected to a digital oscilloscope with an input impedance of 50Ω through an RF coaxial cable to collect the voltage/current waveform output by the signal source.

By using the high-frequency partial discharge signal reconstruction method and system provided in this application, the typical partial discharge signal in the real scene of the substation can be completely reproduced.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

1 is a structural diagram of a high-frequency coupling tooling provided by an embodiment of the present application;

Figure 2 is a schematic diagram of high frequency coupling tooling;

FIG. 3 is a schematic diagram of a high-frequency signal reconstruction process.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

Embodiment 1 of the present application provides a high-frequency partial discharge signal reconstruction system, including a programmable pulse sequence generator, a power divider, a high-frequency current sensor, an oscilloscope, and a broadband impedance matching unit;

The calibration signal output by the programmable pulse sequence generator is connected to an RF power divider with a characteristic impedance of 50Ω through a high-frequency coaxial feeder, and the calibration signal is divided into two outputs, one of which is connected to the oscilloscope with a high-frequency coaxial line for Observe the output of the programmable pulse sequence generator, and the other is connected to the broadband impedance matching unit for calibrating the high-frequency current sensor with a high-frequency coaxial line; the characteristic impedance of the coaxial transmission line is all 50Ω.

The high-frequency coupling tooling is used to install the calibrated high-frequency current sensor. It is a transmission line structure deformed by an RF coaxial line with a characteristic impedance of 50Ω. Its structure diagram is shown in Figure 1. The current sensor to be tested is clamped in the middle of the matching unit. The size of the core wire of the matching unit and the outer casing meet the characteristic impedance of 50Ω. The size of the outer casing is transitioned from the input and output terminals to the center, forming a conical transition structure to meet the broadband matching requirements. The output end of the matching unit is connected to a digital oscilloscope with an input impedance of 50Ω through an RF coaxial cable, and the voltage/current waveform output by the signal source is collected.

The high-frequency coupling tool adopts a coaxial cavity with 50Ω wave impedance, and the injection capacitor C0 selects a high-frequency ceramic capacitor of 100pF±2%.

According to the principle of on-site high-frequency partial discharge detection, the equivalent coupling device in the laboratory is essentially a current loop matched with a 50Ω non-inductive resistance, and the entire current loop is required to be strictly matched in a wide frequency range. Since the calibration tool of the high-frequency partial discharge live detection device is a current loop structure and is not connected to the external circuit, considering the influence of the high-frequency interference signal on the calibration in the substation environment, it is necessary to add an interference signal loop, as shown in the schematic diagram. As shown in Figure 2, in Figure 2, Up-high-frequency partial discharge signal, C0-injection capacitor, Us-interference signal, Rs-50Ω non-inductive resistance, M0-detected instrument, M1-oscilloscope, HFCT-high-frequency current sensor.

When partial discharge occurs in the partial discharge source, a very steep pulse current will be generated along with the discharge process, and a magnetic field will be generated when it flows through the grounding down-conductor, and the magnetic field will be located on a plane perpendicular to the current propagation direction;

Connect the high-frequency current sensor and the phase information sensor to the ground wire of the power equipment to couple energy from the magnetic field generated by the high-frequency partial discharge signal, convert the coupled energy into an electrical signal through the coil, and send the electrical signal to the high-frequency Partial discharge charged detection equipment.

The embodiment of the present application also provides a high-frequency partial discharge signal reconstruction method, including:

Step1. The programmable pulse sequence generating device outputs a voltage waveform U ₁ , which is emitted through high-frequency coupling to generate a current I ₁ ;

Step 2. The high-frequency current sensor receives the current I ₀ generated by the partial discharge, and converts the partial discharge current I ₀ into a voltage waveform U ₀ that the oscilloscope can store through its own transmission impedance;

Step 3. The voltage waveform U ₁ output by the programmable pulse sequence generating device is the same as the partial discharge current I ₀ , and the current I ₁ and the current I ₀ have the same waveform, thereby realizing the waveform reconstruction of the high-frequency pulse current.

Specifically, as shown in the schematic diagram of the high-frequency signal reconstruction process shown in FIG. 3, the current generated by the partial discharge source is I ₀ , and the current I ₀ flows through the high-frequency current sensor. The impedance is Z(jω), which is converted into a voltage waveform U ₀ that can be stored by an oscilloscope through a high-frequency current sensor;

Among them, the relationship between the signal input I ₀ and U ₀ is shown in Equation 1,

U _o (jw)=I ₀ (jw)Z(jw) (1)

The voltage waveform output by the programmable pulse sequence generating device is U ₁ , and then the current generated by high-frequency coupling is I ₁ ; the relationship between the signal waveform U ₁ and U ₀ output by the signal source is

U ₁ (jw)=U ₀ (jw)/Z(jw)=I ₀ (jw) (2)

That is, U ₁ has the same waveform as the original pulse current I ₀ , U _{1 outputs the current I 1 through} a 50Ω resistor, and I ₁ has the same waveform as I ₀ , thus realizing the waveform reconstruction of the high-frequency pulse current.

The above-mentioned embodiments are only specific implementations of the present application, and are used to illustrate the technical solutions of the present application, but not to limit them. Detailed description, those of ordinary skill in the art should understand: any person skilled in the art is within the technical scope disclosed in this application, and it can still modify the technical solutions described in the foregoing embodiments or can easily think of changes, Or equivalently replace some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the present application. All should be covered within the scope of protection of this application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (9)

1. A method for reconstructing a high frequency partial discharge signal, comprising:

programmable pulse sequence generator output voltage waveform U₁Is emitted by high-frequency coupling to generate a current I₁；

The high-frequency current sensor receives the current I generated by partial discharge₀The partial discharge current I is transmitted through the self transmission impedance₀Converting to a voltage waveform U storable by an oscilloscope₀；

Voltage waveform U output by programmable pulse sequence generator₁And a partial discharge current I₀Same, current I₁And current I₀The waveforms are the same, so that the waveform reconstruction of the high-frequency pulse current is realized.

2. The high-frequency partial discharge signal reconstruction method according to claim 1, wherein a current generated by partial discharge of the partial discharge source is I₀Current I of₀Flowing through the high-frequency current sensor as a receiving device with transmission impedance Z (j omega), and converting into voltage waveform U which can be stored in an oscilloscope₀。

3. The high-frequency partial discharge signal reconstruction method according to claim 2, characterized in that the signal input I₀And U₀The relationship of (a) is shown as follows:

U_o(jw)＝I₀(jw)Z(jw)

wherein Z (j ω) is the transmission impedance of the high-frequency current sensor.

4. The high-frequency partial discharge signal reconstruction method according to claim 3, wherein the signal source outputs a signal waveform U₁And U₀The relationship of (1) is:

U₁(jw)＝U₀(jw)/Z(jw)＝I₀(jw)

thus U is₁With the original pulse current I₀Same waveform, U₁Output current I through 50 omega resistor₁，I₁Is also related to₀The waveforms are the same.

5. A high frequency partial discharge signal reconstruction system, comprising: the device comprises a programmable pulse sequence generating device, a power divider, a high-frequency current sensor, an oscilloscope and a broadband impedance matching unit;

the calibration signal output by the programmable pulse sequence generator is connected with an RF power distributor with the characteristic impedance of 50 omega through a high-frequency coaxial feeder line, the calibration signal is divided into two paths to be output, one path of the calibration signal is connected with an oscilloscope through a high-frequency coaxial line and used for observing the output of the programmable pulse sequence generator, and the other path of the calibration signal is connected with a broadband impedance matching unit used for calibrating a high-frequency current sensor through the high-frequency coaxial line; wherein the characteristic impedances of the coaxial transmission lines are all 50 omega.

6. The system for reconstructing high-frequency partial discharge signals according to claim 5, wherein the high-frequency coupling tool is used for mounting a calibrated high-frequency current sensor and is a transmission line structure formed by deforming an RF coaxial line with the characteristic impedance of 50 Ω.

7. The high-frequency partial discharge signal reconstruction system of claim 6, wherein an interference signal loop is added to the high-frequency coupling tool to simulate high-frequency interference signals in a substation environment.

8. The high-frequency partial discharge signal reconstruction system of claim 6, wherein the high-frequency coupling tool adopts a coaxial cavity with 50 Ω wave impedance, and the injection capacitor C0 adopts a high-frequency ceramic capacitor with 100pF ± 2%.

9. The system for reconstructing high frequency partial discharge signals according to claim 5, wherein the high frequency current sensor is clamped in the middle of the matching unit, the core wire and the outer shell of the matching unit have dimensions that satisfy a characteristic impedance of 50 Ω, the outer shell has dimensions that transition from the input and output terminals to the center to form a tapered transition structure that satisfies the requirement of wideband matching, and the output end of the matching unit is connected to a digital oscilloscope having an input impedance of 50 Ω through an RF coaxial cable to collect the voltage/current waveforms output by the signal source.

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