CN103487728A - Narrow-band electromagnetic wave signal coupling method and detecting system for measuring GIS partial discharge - Google Patents

Abstract

The invention discloses a narrow-band electromagnetic wave signal coupling method and detecting system for measuring GIS partial discharge. The narrow-band electromagnetic wave signal coupling method includes the following steps that (1) the cut-off frequency fc, radiated by a poured hole in a metal ring of GIS equipment, of an electromagnetic dominant mode is calculated; (2) the cut-off frequency fc is used as the central frequency of the detecting system, and the detecting system is mainly formed by sequentially connecting a narrow-band antenna, a filter, an amplifier and a signal collector in a communicating mode; (3) the narrow-band antenna is arranged directly facing the poured hole; (4) the narrow-band antenna enables electromagnetic wave signals radiated by the poured hole to be converted into voltage signals to be transmitted to the filter, the filter conducts filtering on the voltage signals, and the voltage signals are received by the signal collector to be recoded and analyzed being amplified by the amplifier. According to the narrow-band electromagnetic wave signal coupling method, the gain within the effective narrow-band range is far higher than that of an existing broad-band detecting method. Moreover, interference signals within the broad frequency band range are avoided, and the signal to noise ratio is greatly improved. The requirements for on-site tests are completely met.

Description

Measure arrowband electromagnetic wave signal coupling process and the detection system of GIS shelf depreciation

Technical field

The present invention relates to a kind of arrowband electromagnetic wave signal coupling process of the GIS of measurement apparatus local discharge, also relate to the detection system of using this arrowband electromagnetic wave signal coupling process.

Background technology

Along with the continuous increase of society to electricity needs, power industry is developed rapidly, and at present, the safe operation of large-scale power transmission network has become the significant problem that power industry is paid close attention to.Research shows, gas insulated combined electrical equipment (Gas Insulated Switchgear, hereinafter to be referred as GIS) and potential device inside take insulation fault as many, and the tendency of insulation fault often shows as shelf depreciation, it is generally acknowledged, shelf depreciation in high-tension apparatus has a strong impact on Electric Field Distribution, causes electric field distortion and insulating material corrosion, finally causes insulation breakdown.The broadband electromagnetic wave signal that shelf depreciation in GIS is usually expressed as the fast-pulse electric current and excites thus.The frequency range of electromagnetic wave signal can reach several GHz, even higher.By being coupled, this electromagnetic wave signal can detect the partial discharges fault that occurs in the GIS device interior.In order to improve signal to noise ratio (S/N ratio), avoid the complicated undesired signals such as the on-the-spot corona existed, the working band of existing detection system mainly in superfrequency (Ultra High Frequency, hereinafter to be referred as UHF) band limits, that is: 0.3～1.5GHz.In recent years, GIS shelf depreciation UHF detection technique has obtained greatly developing and applying in China.Apply this technology and repeatedly found the inner shelf depreciation defect of GIS, avoided the generation of GIS insulation fault, for the safe and reliable operation that guarantees electric system has been made significant contribution.

As shown in Figures 1 to 3, for receiving the electromagnetic installation of sensors of UHF in GIS device interior (referring to Fig. 1,2) or being installed on disc insulator 10 outside surfaces (referring to Fig. 3).UHF sensor 1 when GIS equipment 2 inside or disc insulator outside surface, the non-constant width of electromagnetic wave signal frequency that it receives.From signal spectrum, in 300MHz～1.5GHz frequency range, energy distribution is arranged.Therefore, existing UHF sensor all adopts the broadband sensor, such as capacitance type transducers, equiangular spiral antenna, log-periodic antenna, bow-tie type antenna etc.; Existing UHF amplifier and wave filter also all adopt the broadband operation pattern.Detection system shown in Fig. 2 comprises coupling mechanism 3, conversion connector 4, UHF sensor 1, cable 6 and oscillograph 7.Detection system shown in Fig. 3 comprises broad-band antenna 8 and UHF detector 9.

In recent years, along with the development of urban planning and construction and the development of backcountry power transmission network, in order to save transformer station's floor area and to reduce operation maintenance, the GIS equipment adopted in newly-built transformer station is more and more.In order to improve Earthing Reliability, to prevent the corrosion of rugged surroundings to insulator, on increasing GIS equipment, adopted the insulator with becket.Becket wraps up whole insulator.For the ease of the insulator castable, a plug hole is arranged, for pouring into epoxy material on becket.Owing on existing most of GIS equipment, built-in UHF sensor not being installed, and because the stopping of becket, the UHF electromagnetic wave can only be through plug hole to external radiation.But, extremely faint to extraradial UHF signal, utilize existing external broad-band antenna and detection system, extremely low because of the sensitivity of detection system, 100pC and above shelf depreciation only can be detected, can not reach the requirement of Site Detection.

Summary of the invention

One object of the present invention is to provide a kind of arrowband electromagnetic wave signal coupling process that can improve the measurement GIS shelf depreciation of detection sensitivity and signal to noise ratio (S/N ratio), can reach the requirement of On-site Partial Discharge Detection in GIS.

Above-mentioned purpose of the present invention realizes by the following technical solutions: a kind of arrowband electromagnetic wave signal coupling process of the GIS of measurement shelf depreciation is characterized in that comprising the following steps:

(1) calculate the cutoff frequency f of the electromagnetic wave master mould that the plug hole by becket on GIS equipment gives off _c;

(2) with cutoff frequency f _cas the centre frequency of detection system, detection system is mainly communicated to connect and forms successively by narrow-band antenna, wave filter, amplifier and signal picker;

(3) narrow-band antenna is arranged over against plug hole;

(4) the electromagnetic wave signal that narrow-band antenna will be given off by plug hole changes into voltage signal and is sent to wave filter, after wave filter carries out filtering and amplifies processing by amplifier this voltage signal, receive this voltage signal by signal picker and recorded and analyze, complete the measurement to the GIS shelf depreciation.

The gain of the present invention in effective arrowband scope be far away higher than existing wide band detection method, and avoided the undesired signal in broad frequency range, greatly improved signal to noise ratio (S/N ratio).Reached the requirement of Site Detection fully.

As a kind of recommendation embodiment of the present invention, the centre frequency of described narrow-band antenna is cutoff frequency f _c, bandwidth of operation is 50～150MHZ, the gain of narrow-band antenna is compared with broad-band antenna and is greatly improved, and antijamming capability is strong.The passband of described wave filter is f _c-50MHZ～f _c+ 50MHZ, further improved signal to noise ratio (S/N ratio), and the minimum value of the analog bandwidth of described signal picker is at most f _c-50MHZ.

The work bandwidth of amplifier of the present invention is f _c-50MHZ～f _c+ 50MHZ, improved detection sensitivity greatly.

As one embodiment of the present invention, step (1) in, described plug hole is rectangular opening, cutoff frequency f _ccomputing formula be:

$f_c=\frac{c}{2a\sqrt{{\mathrm{\μ}}_r{\mathrm{\ϵ}}_r}}---\left(1\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; The length that a is plug hole, what b was plug hole is wide, ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

As another embodiment of the invention, step (1) in, described plug hole is circular hole, cutoff frequency f _ccomputing formula be:

$f_c=\frac{u_{11}^{\&prime;}\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA0000375082540000011.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{\&pi;r}\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(2\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; u ₁₁' be constant; The radius that r is plug hole; ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

Another object of the present invention is to provide a kind of detection system of using the arrowband electromagnetic wave signal coupling process of above-mentioned measurement GIS shelf depreciation.

Above-mentioned purpose of the present invention realizes by the following technical solutions: a kind of detection system of using the arrowband electromagnetic wave signal coupling process of above-mentioned measurement GIS shelf depreciation, it is characterized in that: the narrow-band antenna that it is mainly placed by the plug hole for over against the upper becket of GIS, wave filter, amplifier and signal picker form, the voltage signal output end of described narrow-band antenna is connected with the voltage signal input end of wave filter, the voltage signal output end of described wave filter is connected with the voltage signal input end of amplifier, the voltage signal output end of described amplifier is connected with the voltage signal input end of signal picker, described narrow-band antenna is sent to wave filter after receiving the electromagnetic wave signal given off by plug hole and being translated into voltage signal, be resent to amplifier after device filtering processing after filtering and carry out the signal amplification, finally be sent to signal picker and recorded and analyze.

The cutoff frequency f of the electromagnetic wave master mould that the plug hole that the centre frequency of described narrow-band antenna is becket on GIS equipment gives off _c, the bandwidth of operation of narrow-band antenna is 50～150MHZ, the gain of narrow-band antenna improves greatly than broad-band antenna, and antijamming capability is strong.The passband of described wave filter is f _c-50MHZ～f _c+ 50MHZ, further improved signal to noise ratio (S/N ratio), and the minimum value of the analog bandwidth of described signal picker is at most f _c-50MHZ.

The work bandwidth of amplifier of the present invention is f _c-50MHZ～f _c+ 50MHZ, improved detection sensitivity greatly.

Plug hole of the present invention is rectangular opening, cutoff frequency f _ccomputing formula be:

$f_c=\frac{c}{2a\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(1\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; The length that a is plug hole, what b was plug hole is wide, ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

Plug hole of the present invention is circular hole, cutoff frequency f _ccomputing formula be:

$f_c=\frac{u_{11}^{\&prime;}\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA0000375082540000011.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{\&pi;r}\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(2\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; u ₁₁' be constant; The radius that r is plug hole; ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

Compared with prior art, the present invention has following significant effect:

The gain of the present invention in effective arrowband scope is far away higher than existing wide band detection method, highly sensitive, and has avoided the undesired signal in broad frequency range, has greatly improved signal to noise ratio (S/N ratio).Reached the requirement of Site Detection fully.

The accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Fig. 1 has now for receiving the schematic diagram of the electromagnetic installation of sensors of UHF in GIS equipment;

Fig. 2 is the structural representation of detection system when measuring of the built-in UHF sensor that comprises Fig. 1;

Fig. 3 has now for receiving the electromagnetic installation of sensors of UHF in the schematic diagram of disc insulator outside surface;

Fig. 4 is the principle schematic that the embodiment of the present invention 1 is calculated rectangle plug hole cutoff frequency;

Fig. 5 is the principle schematic that the embodiment of the present invention 2 is calculated circular plug hole cutoff frequency;

Schematic diagram when Fig. 6 is detection system measurement of the present invention.

Embodiment

Embodiment 1

A kind of arrowband electromagnetic wave signal coupling process of measuring the GIS shelf depreciation of the present invention comprises the following steps:

(1) calculate the cutoff frequency f of the electromagnetic wave master mould that the plug hole by becket 18 on GIS equipment gives off _c; In the present embodiment, GIS equipment is the 252kVGIS of certain manufacturer production.Plug hole 15 on this GIS insulator 19 is approximately rectangle, and referring to Fig. 4, according to Electromagnetic theory, the main mould in rectangular waveguide inside is TE ₁₀ripple, the computing formula of its cutoff frequency is:

$f_c=\frac{c}{2a\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(1\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum, that is: 3 * 10 ⁸m/s; The length that a is plug hole, what b was plug hole is wide, ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

The rectangular waveguide cross section is rectangle, and its size (long * wide) is: 0.045m * 0.020m.The relative permeability μ of its inner mould material _rbe 1, relative dielectric constant ε _rbe 3.8.Make a=0.045m, b=0.020m; C=3 * 10 ⁸m/s, μ _r=1, ε _r=3.8.Calculate cutoff frequency according to formula (1), obtain: f _c=1.71GHz.

The measurement bandwidth of determining detection system is 1.66～1.76GHz.

(2) with cutoff frequency f _cas the centre frequency of detection system, detection system is mainly communicated to connect and forms successively by narrow-band antenna 11, wave filter 12, amplifier 13 and signal picker 14, and the centre frequency of narrow-band antenna 11 is cutoff frequency f _c=1.71GHz, generally, more than 1.5GHz, the bandwidth of operation of narrow-band antenna is 100MHZ, and this narrow-band antenna has stronger directivity and gain, and the gain of narrow-band antenna improves greatly than broad-band antenna, and antijamming capability is strong.The passband of wave filter is 1.66～1.76GHz, and at the cutoff frequency place, gain is-3dB, and stop band gain is-20dB further to have improved signal to noise ratio (S/N ratio).The work bandwidth of amplifier is 1.66～1.76GHz, in the gain of cutoff frequency place, is 3dB, and passband gain is 20dB, has greatly improved detection sensitivity.

In the present embodiment, signal picker adopts the Wavemaster8620A type oscillograph of U.S. Li Ke company, and its analog bandwidth can reach 0-6GHz.The minimum value that is the analog bandwidth of signal picker is at most f _c-50MHZ.

(3), while measuring, narrow-band antenna 11 is arranged over against plug hole;

(4) the electromagnetic wave signal that narrow-band antenna 11 will be given off by plug hole changes into voltage signal and is sent to wave filter 12, after this voltage signal is carried out filtering and is amplified processing by amplifier 13 by wave filter 12, receiving this voltage signal by signal picker 14 is recorded and is analyzed, test result shows, to the output amplitude of the shelf depreciation of GIS inside 5pC, is 10mV.Therefore, the present invention is used in the shelf depreciation that GIS inside is detected at the plug hole place.

The gain of the present invention in effective arrowband scope is far away higher than existing wide band detection method, highly sensitive, and has avoided the undesired signal in broad frequency range, has greatly improved signal to noise ratio (S/N ratio).Reached the requirement of Site Detection fully.

As shown in Figure 6, use the detection system 17 of the arrowband electromagnetic wave signal coupling process of above-mentioned measurement GIS shelf depreciation, narrow-band antenna 11, wave filter 12, amplifier 13 and signal picker 14 that it is mainly placed by the plug hole for over against the upper becket of GIS form, the voltage signal output end of narrow-band antenna 11 is connected with the voltage signal input end of wave filter 12, the voltage signal output end of wave filter 12 is connected with the voltage signal input end of amplifier 13, and the voltage signal output end of amplifier 13 is connected with the voltage signal input end of signal picker 14; Narrow-band antenna 11 is sent to wave filter 12 after receiving the electromagnetic wave signal given off by plug hole and being translated into voltage signal, be resent to amplifier 13 after device 12 filtering processing after filtering and carry out the signal amplification, finally be sent to signal picker 14 and recorded and analyze.

The cutoff frequency f of the electromagnetic wave master mould that the plug hole that wherein, the centre frequency of narrow-band antenna is becket on GIS equipment gives off _c=1.71GHz, the bandwidth of operation of narrow-band antenna is 100MHZ, the passband of wave filter is f _c-50MHZ～f _c+ 50MHZ, be 1.66～1.76GHz, and at the cutoff frequency place, gain is-3dB, and stop band gain is-20dB; The analog bandwidth of signal picker is 0-6GHz, and the work bandwidth of amplifier is f _c-50MHZ～f _c+ 50MHZ, be 1.66～1.76GHz, in the gain of cutoff frequency place, is 3dB, and passband gain is 20dB.

Embodiment 2

The difference of the present embodiment and embodiment 1 is: as shown in Figure 5, plug hole 16 is circular hole, and the circular waveguide cross section is circular, and according to Electromagnetic theory, the main mould in circular waveguide inside is TE ₁₁ripple, cutoff frequency f _ccomputing formula be:

$f_c=\frac{u_{11}^{\&prime;}\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA0000375082540000011.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{\&pi;r}\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(2\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; u ₁₁' be constant value 1.841; The radius that r is plug hole; ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

Embodiments of the present invention are not limited to this; according to foregoing of the present invention; ordinary skill knowledge and customary means according to this area; do not breaking away under the above-mentioned basic fundamental thought of the present invention prerequisite; the bandwidth of operation of narrow-band antenna of the present invention is 50～150MHZ; therefore the present invention can also make modification, replacement or the change of other various ways, within all dropping on rights protection scope of the present invention.

Claims (10)

1. an arrowband electromagnetic wave signal coupling process of measuring the GIS shelf depreciation is characterized in that comprising the following steps:

(1) calculate the cutoff frequency f of the electromagnetic wave master mould that the plug hole by becket on GIS equipment gives off _c;

(2) with cutoff frequency f _cas the centre frequency of detection system, detection system is mainly communicated to connect and forms successively by narrow-band antenna, wave filter, amplifier and signal picker;

(3) narrow-band antenna is arranged over against plug hole;

(4) the electromagnetic wave signal that narrow-band antenna will be given off by plug hole changes into voltage signal and is sent to wave filter, after wave filter carries out filtering and amplifies processing by amplifier this voltage signal, receive this voltage signal by signal picker and recorded and analyze, complete the measurement to the GIS shelf depreciation.

2. the arrowband electromagnetic wave signal coupling process of measurement according to claim 1 GIS shelf depreciation, it is characterized in that: the centre frequency of described narrow-band antenna is cutoff frequency f _c, bandwidth of operation is 50～150MHZ, the passband of described wave filter is f _c-50MHZ～f _c+ 50MHZ, the minimum value of the analog bandwidth of described signal picker is at most f _c-50MHZ.

3. the arrowband electromagnetic wave signal coupling process of measurement according to claim 2 GIS shelf depreciation, it is characterized in that: the work bandwidth of described amplifier is f _c-50MHZ～f _c+ 50MHZ.

4. according to the arrowband electromagnetic wave signal coupling process of the described measurement of claim 1～3 any one GIS shelf depreciation, it is characterized in that: step (1) in, described plug hole is rectangular opening, cutoff frequency f _ccomputing formula be:

$f_c=\frac{c}{2a\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(1\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; The length that a is plug hole, what b was plug hole is wide, ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

5. according to the arrowband electromagnetic wave signal coupling process of the described measurement of claim 1～3 any one GIS shelf depreciation, it is characterized in that: step (1) in, described plug hole is circular hole, cutoff frequency f _ccomputing formula be:

$f_c=\frac{u_{11}^{\&prime;}c}{2\mathrm{\&pi;r}\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(2\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; u ₁₁' be constant; The radius that r is plug hole; ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

6. a right to use requires the detection system of the arrowband electromagnetic wave signal coupling process of 1 described measurement GIS shelf depreciation, it is characterized in that: narrow-band antenna, wave filter, amplifier and signal picker that it is mainly placed by the plug hole for over against the upper becket of GIS form, the voltage signal output end of described narrow-band antenna is connected with the voltage signal input end of wave filter, the voltage signal output end of described wave filter is connected with the voltage signal input end of amplifier, and the voltage signal output end of described amplifier is connected with the voltage signal input end of signal picker; Described narrow-band antenna is sent to wave filter after receiving the electromagnetic wave signal given off by plug hole and being translated into voltage signal, be resent to amplifier after device filtering processing after filtering and carry out the signal amplification, finally be sent to signal picker and recorded and analyze.

7. the detection system of the arrowband electromagnetic wave signal coupling process of GIS shelf depreciation is measured in use according to claim 6, it is characterized in that: the cutoff frequency f of the electromagnetic wave master mould that the plug hole that the centre frequency of described narrow-band antenna is becket on GIS equipment gives off _c, the bandwidth of operation of narrow-band antenna is 50～150MHZ, the passband of described wave filter is f _c-50MHZ～f _c+ 50MHZ, the minimum value of the analog bandwidth of described signal picker is at most f _c-50MHZ.

8. the detection system of the arrowband electromagnetic wave signal coupling process of GIS shelf depreciation is measured in use according to claim 7, and it is characterized in that: the work bandwidth of described amplifier is f _c-50MHZ～f _c+ 50MHZ.

9. measure the detection system of the arrowband electromagnetic wave signal coupling process of GIS shelf depreciation according to the described use of claim 6～8 any one, it is characterized in that: described plug hole is rectangular opening, cutoff frequency f _ccomputing formula be:

$f_c=\frac{c}{2a\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(1\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; The length that a is plug hole, what b was plug hole is wide, ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

10. measure the detection system of the arrowband electromagnetic wave signal coupling process of GIS shelf depreciation according to the described use of claim 6～8 any one, it is characterized in that: described plug hole is circular hole, cutoff frequency f _ccomputing formula be:

$f_c=\frac{u_{11}^{\&prime;}c}{2\mathrm{\&pi;r}\sqrt{{\mathrm{\&mu;}}_r{\mathrm{\&epsiv;}}_r}}---\left(2\right)$

Wherein, c is electromagnetic wave velocity of wave in a vacuum; u ₁₁' be constant; The radius that r is plug hole; ε _r, μ _rbe respectively relative dielectric constant and the relative permeability of the dielectric material of filling in plug hole.

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