CN107884691A - A kind of SF6Gas-insulated switchgear built-in electrical insulation trouble-shooter and method - Google Patents

Abstract

The invention provides a device and method for diagnosing internal insulation faults of SF ₆ gas insulated switchgear. The gas detection tube detects SO ₂ and HF generated by the decomposition of SF ₆ gas insulated switchgear during operation and corrects the detection results of SO ₂ and HF gas components in the electrochemical sensor; the electrochemical sensor detects that the SF ₆ gas insulated switchgear is running The content of SO ₂ , H ₂ S , CO and HF gas components produced by decomposition during the process; gas chromatograph _for CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , The concentration of H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ is calibrated; the gas phase mass spectrometer corrects the concentration calibrated by the gas chromatograph; the computer diagnoses the internal insulation fault of the SF ₆ gas insulated switchgear according to the concentration corrected by the gas phase mass spectrometer; The SF ₆ decomposition products produced by different types of faults in the operation of faulty equipment are different, so a detection device consisting of a gas detection tube, an electrochemical sensor, a gas chromatograph and a gas mass spectrometer is used for qualitative and quantitative detection.

Description

Device and method for diagnosing internal insulation faults of SF6 gas insulated switchgear

technical field

The invention belongs to the technical field of insulation fault diagnosis of switchgear, and in particular relates to a device and method for diagnosing internal insulation faults of SF ₆ gas insulated switchgear.

Background technique

With the development of the power industry, SF ₆ switchgear gradually replaces the traditional oil-filled equipment, which plays a key role in the safe, stable and economical operation of the power system. Due to possible defects in the design, manufacture, installation, operation and maintenance of the equipment, partial discharge or even arc discharge may _occur inside the equipment, which seriously threatens the safety of the power grid. Running is important. In the early stage of fault diagnosis of SF ₆ switchgear, it is difficult to detect fault defects inside the equipment by traditional electrical test methods. Field operation experience has shown that by detecting SF ₆ gas decomposition products, latent faults in the equipment can be found in a timely and effective manner, and equipment faults can be located.

In recent years, China's power operation units have carried out a large number of detections of SF ₆ gas decomposition products in switchgear. Fujian, Guangdong, Shaanxi and Anhui provincial power companies and their scientific research institutions have tested the fully enclosed combined electrical appliances (gasinsulated switchgear, GIS), circuit breakers, etc. of their power grids. General testing of SF ₆ switchgear such as switches. Some achievements have been made, and a large amount of operation data has been accumulated for equipment maintenance, and then technical guidance for equipment condition maintenance is provided. Based on this, the application of SF ₆ gas detection and analysis method in switchgear has a great prospect. In the SF ₆ switchgear in operation, the insulation strength is reduced due to the switch operation or the internal defects of the equipment. And due to the widespread application of SF ₆ switchgear in China's power grid. Therefore, it is necessary to propose a device and method for diagnosing internal insulation faults of SF ₆ gas insulated switchgear.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a device and method for diagnosing internal insulation faults of SF ₆ gas insulated switchgear.

The present invention adopts following technical scheme:

A device for diagnosing internal insulation faults of SF ₆ gas insulated switchgear, comprising:

A gas detection tube that detects SO ₂ and HF generated during the operation of SF ₆ gas insulated switchgear and corrects the detection results of SO ₂ and HF gas components in the electrochemical sensor;

An electrochemical sensor that detects the contents of SO ₂ , H ₂ S, CO and HF gas components generated by the decomposition of SF ₆ gas insulated switchgear during operation;

A gas chromatograph for calibrating the concentration of CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ generated during the operation of SF ₆ gas insulated switchgear;

A gas-mass spectrometer that corrects the concentration calibrated by the gas chromatograph;

A computer for diagnosing internal insulation faults of SF ₆ gas insulated switchgear based on the concentration corrected by the gas phase mass spectrometer;

The output end of the electrochemical sensor, the output end of the gas chromatograph, and the output end of the gas phase mass spectrometer are all connected to the computer.

The gas detection tube includes: a glass tube that passes into the gas to be detected; both sides of the glass tube are provided with blockages, the space between the blockages is used as a reaction space, and the outer wall of the glass tube is provided with a scale, and the reaction space is in line with the scale. The corresponding part is coated with an indicator, and the gas to be detected enters the reaction space through the blockage on one side in the glass tube to chemically react with the indicator to change the color of the indicator, and the length of the color change of the indicator can be read through the scale That is to get the concentration of _SO2 or the concentration of HF.

The indicators are NaOH and iodine.

The electrochemical sensor determines the content of H ₂ S and the content of CO gas according to the change of the surface resistance value of the semiconductor after passing through other components to be detected.

The gas chromatograph uses helium as the carrier gas, and directly calibrates each gas component according to the chromatographic peaks in the gas chromatogram, thereby obtaining CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ content.

The method for diagnosing internal insulation faults of SF ₆ gas insulated switchgear using the device includes:

Obtain the gas to be detected from inside the SF ₆ gas insulated switchgear;

Pass the gas to be detected into the gas detection tube, and detect the SO ₂ and HF produced by the decomposition of SF ₆ gas insulated switchgear during operation. SO ₂ and HF react with the indicator in the gas detection tube to make the indicator change color, through The length of the color change reflects the corresponding substance concentration, and the corresponding concentration value is read from the scale;

Quantitative detection of SO ₂ , H ₂ S, CO and HF gas components using electrochemical sensors;

Use the gas chromatograph to simultaneously detect the gas component content of CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ that have not been detected by the gas detection tube and the electrochemical sensor;

Use gas phase mass spectrometer to detect the content of CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , SO ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ gas components that have not been detected by gas detection tubes and electrochemical sensors , if the detected gas component content is different from that detected by the gas chromatograph, the detection result of the gas chromatograph shall prevail;

Carry out fault diagnosis on the internal insulation condition of the switchgear according to the test results:

If the detected SF ₆ gas insulated switchgear decomposed during the operation process contains the highest SOF ₂ content in the decomposed gas and two products of S ₂ F ₁₀ and S ₂ OF ₁₀ are detected in the decomposed gas, then the current fault type is spark discharge;

If the content of SO ₂ F ₂ and SOF ₂ in the gas decomposed during the operation of the detected SF ₆ gas insulated switchgear exceeds the set value, the current fault type is arc discharge;

If the detected content of H ₂ S and CF ₄ in the gas decomposed during the operation of SF ₆ gas insulated switchgear exceeds the set value, the current fault type is solid insulation damage.

Beneficial effect:

In the operation of faulty equipment, because different fault types produce different SF ₆ decomposition products, a detection device consisting of a gas detection tube, an electrochemical sensor, a gas chromatograph and a gas mass spectrometer is used for qualitative and quantitative detection. The detection result of the gas detection tube is used to calibrate the electrochemical sensor, so that the detection result of the electrochemical sensor is more accurate. The detection result of the gas chromatograph is then calibrated by the gas phase mass spectrometer, so that the detection result of the gas chromatograph is more accurate. After the qualitative and quantitative detection of the SF ₆ decomposition products in the detection device, the fault diagnosis of the internal insulation status of the switchgear is carried out by using the corresponding relationship between different discharge types and the gas decomposition products produced.

Description of drawings

Fig. 1 is a schematic diagram of a gas detection tube in a specific embodiment of the present invention, wherein 1-glass tube, 2-blockage, 3-indicator, 4-scale;

Fig. 2 is a schematic diagram of an electrochemical sensor in a specific embodiment of the present invention;

Fig. 3 is a schematic diagram of a gas chromatograph in a specific embodiment of the present invention;

Fig. 4 is the chromatogram of SF _decomposed gas in the specific embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

A device for diagnosing internal insulation faults of SF ₆ gas insulated switchgear, comprising:

A gas detection tube that detects SO ₂ and HF generated during the operation of SF ₆ gas insulated switchgear and corrects the detection results of SO ₂ and HF gas components in the electrochemical sensor;

An electrochemical sensor that detects the contents of SO ₂ , H ₂ S, CO and HF gas components generated by the decomposition of SF ₆ gas insulated switchgear during operation;

A gas chromatograph for calibrating the concentration of CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ generated during the operation of SF ₆ gas insulated switchgear;

A gas-mass spectrometer that corrects the concentration calibrated by the gas chromatograph;

A computer for diagnosing internal insulation faults of SF ₆ gas insulated switchgear based on the concentration corrected by the gas phase mass spectrometer;

The output end of the electrochemical sensor, the output end of the gas chromatograph, and the output end of the gas phase mass spectrometer are all connected to the computer.

As shown in Figure 1, it is a gas detection tube, including: a glass tube 1 that passes into the gas to be detected; both sides of the glass tube 1 are provided with blockages 2, and the space between the blockages 2 is used as a reaction space, and the outer wall of the glass tube 1 The scale 4 is set, and the indicator 3 is coated in the reaction space corresponding to the scale 4. The gas to be detected enters the reaction space through the blockage 2 on one side in the glass tube 1 and chemically reacts with the indicator 3 to make the indicator 3, the color changes, and the length of the color change of the indicator 3 is read through the scale 4 to obtain the concentration of _SO2 or HF.

Both _SO2 and HF are strongly acidic substances, HF can react with NaOH, _SO2 can chemically react with iodine, so NaOH and iodine are selected as indicators respectively, HF reacts with NaOH or _SO2 reacts chemically with iodine The indicator changes color during the reaction, and the length of the color change is proportional to the concentration of SO ₂ and iodine. The concentration value can be easily read from the surface scale 4 of the gas detection tube, and the operation is simple and the accuracy is high. Their chemical reactions are

HF+NaOH＝NaF+H ₂ O purple red to yellow;

SO ₂ +I ₂ +2H ₂ O=H ₂ SO ₄ +2HI Blue to white.

It can be seen from the chemical reaction formula that HF adopts acid-base reaction, and _SO2 adopts redox reaction. Since the reaction mechanism is different, the two substances do not need to be separated. The gas detection tube can detect SO ₂ or HF with a volume fraction of 10 ^-6 , and this method has been successfully put into commercial application because of its simplicity. However, it is easily affected by temperature, humidity and storage time, and has no detection effect on other major decomposition gases, and cannot fully reflect the composition of SF ₆ discharge decomposition gases.

The electrochemical sensor shown in Figure 2 can accurately detect SO ₂ , H ₂ S , CO and HF gas components, but the accuracy is lower than that of the gas detection tube, so the gas whose content of SO ₂ and HF has been confirmed is passed into the electrode The chemical sensor determines the content of H ₂ S and CO gas according to the change of semiconductor surface resistance value. The contents of SO ₂ , H ₂ S, CO and HF gas components were detected. Due to the slight deviation between the content of SO ₂ and HF in the detection results and the detection results of the gas detection tube, the electrochemical sensor detection was corrected by the detection results of the gas detection tube. As a result, a second measurement was carried out, and the content of H ₂ S and CO gas was obtained after the second detection, but the content of CF ₄ , SO ₂ F ₂ , SOF ₂ and other components still needs to be further tested.

Pass the gas to be detected into the gas chromatograph shown in Figure 3, the gas chromatograph can simultaneously detect CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , SO ₂ , H ₂ O that have not been detected by the above two instruments and other important gas components, using helium as the carrier gas, the chromatographic column (capillary column CP-Sil5CB60mtr0.32mm) selects stainless steel column, PorapakQ (80/100 mesh), 3 ~ 4m (L) × 3mm (φ); heating Chamber program: initial temperature: 60-80°C, final temperature: 120-180°C, heating rate: 10-20°C/min. The gas chromatogram shown in Figure 4 is obtained, and the gas components are directly calibrated according to the chromatographic peaks in the gas chromatogram, so as to obtain CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S For the content of ₂ F ₁₀ and S ₂ OF ₁₀ , the voltage U is used to indicate the change of the relative content with time. From Figure 4, it can be concluded that the CF ₄ content exceeds the range of the IEC2010 standard. When the insulation damage occurs in the solid, the decomposition of C and the F in the gas combine to produce excess CF ₄ , so it is judged that there is solid insulation damage inside the switchgear.

The gas chromatograph corrects the concentration calibrated by the gas chromatograph: if the detected gas component content is different from that detected by the gas chromatograph, the detection result of the gas chromatograph shall prevail; According to the difference of motion law in the magnetic field, it is separated according to the ratio of mass to charge, so as to measure the mass and intensity distribution of the particles. The gas phase mass spectrometer gives the elemental composition, molecular weight, empirical formula and molecular structure information of the compound, and due to the fast detection speed, high sensitivity and strong qualitative specificity, the gas after separation by the mass spectrometer is used to verify that the chromatograph is detected accurately. No need to correct secondary measurements.

The method for diagnosing internal insulation faults of SF ₆ gas-insulated switchgear using the above-mentioned device includes:

Step 1: Obtain the gas to be detected from inside the SF ₆ gas insulated switchgear.

Step 2: Pass the gas to be detected into the gas detection tube, and detect SO ₂ and HF produced by the decomposition of SF ₆ gas insulated switchgear during operation. SO ₂ and HF react with NaOH in the gas detection tube to make the indicator change color , _SO2 chemically reacts with the iodine in the gas detection tube to cause the indicator to change color, and the corresponding substance concentration is reflected by the length of the color change, and the corresponding concentration value is read from the surface scale or tape of the gas detection tube.

Step 3: Quantitative detection of SO ₂ , H ₂ S and CO gas components using electrochemical sensors: Pass the gas to be detected into the electrochemical sensor, and the surface resistance of the semiconductor will change. According to the surface resistance of the semiconductor and the gas components The relationship between the contents determines the contents of SO ₂ , H ₂ S and CO gas components.

The operation shows that the cross-interference between different gases by the electrochemical sensor seriously limits the detection accuracy of the method. At the same time, there are problems such as limited detection components, self-decay, zero point and temperature drift, and short life. The instrument is regularly checked to ensure the accuracy and validity of the test results. Table 1 shows the inspection methods and inspection indicators of electrochemical sensors, and the inspection system of class A (suitable for detecting latent faults) and class B (suitable for detecting faulty equipment) of detectors.

Table 1 Inspection Index

Step 4: Simultaneously detect CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ gas components that have not been detected by gas detection tubes and electrochemical sensors by gas chromatography Content: Pass the gas to be detected into the gas chromatograph, use helium as the carrier gas to obtain the gas chromatogram, and directly calibrate the content of each gas component according to the chromatographic peak, so as to obtain CF ₄ , SF ₆ , 8O ₂ F ₂ , SOF ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ content;

Gas chromatograph is a kind of separation and analysis instrument, which utilizes the different distribution coefficients (or adsorption coefficients, permeability) of different substances in two phases. When the two phases move relative to each other, these substances are repeatedly distributed in the two phases. to achieve separation. After detectors and recorders, these separated components become individual chromatographic peaks. The gas chromatograph can simultaneously detect gas components such as CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , SO ₂ , and H ₂ O whose volume fraction is as low as 10 ^-6 . The gas chromatograph shown in Figure 3 usually consists of the following five parts: ① carrier gas system (including gas source and flow adjustment and measuring components, etc.); ② sampling system (including sampling device and vaporization chamber) ; ③Separation system (mainly chromatographic column); ④Detection and recording system (including detector and recorder); ⑤Auxiliary system (including temperature control system, data processing system (installed in computer), etc.).

According to the recommendation of IEC60480, the following analysis conditions are adopted for gas chromatographic analysis: ① Carrier gas: helium or hydrogen (10-25mL/min); the flow rate should be adjusted according to the chromatographic analysis column used to optimize the analysis effect; ② Chromatographic analysis column: stainless steel Column, PorapakQ (80/100 mesh), 3 ~ 4m (L) × 3mm (φ); ③ heating chamber program: initial temperature: 60 ~ 80 ℃, final temperature: 120 ~ 180 ℃, heating rate: 10 ~ 20 °C/min.

The gas chromatograph needs to calibrate the concentration of the decomposed gas components, and each gas component can be calibrated directly according to the chromatographic peak. Due to the instability of some decomposed gas compounds, direct calibration is very difficult. So usually an indirect calibration is performed using an alternative method.

Step 5: Use gas phase mass spectrometer to detect CF ₄ , SF ₆ , SO ₂ F ₂ , SOF ₂ , SO ₂ , H ₂ O, S ₂ F ₁₀ and S ₂ OF ₁₀ gases that have not been detected by the gas detection tube and electrochemical sensor Component content, if the detected gas component content is different from that detected by the gas chromatograph, the detection result of the gas chromatograph shall prevail;

The gas phase mass spectrometer is based on the difference of the movement rules of the charged particles in the electric field or magnetic field, and realizes the separation according to the mass-to-charge ratio, so as to measure the mass and intensity distribution of the particles. The main feature of the gas phase mass spectrometer is that it can give the elemental composition, molecular weight, empirical formula and molecular structure information of the compound. It has the advantages of fast detection speed, high sensitivity and strong qualitative specificity.

Mass spectrometry is based on the difference in motion of charged particles in an electric field or magnetic field, and separates them according to their mass-to-charge ratio, thereby measuring the mass and intensity distribution of the particles. The main feature of mass spectrometry is that it can give the elemental composition, molecular weight, empirical formula and molecular structure information of the compound. It has the advantages of fast detection speed, high sensitivity and strong qualitative specificity.

The relationship between the distance a charged ion moves in an electric field and its molecular weight is determined by its own properties, where

In the formula: m represents the molecular mass; B represents the magnetic field strength; r represents the radius of the track; e represents the electric charge; v represents the voltage. It can be seen from the formula that the molecular mass is proportional to (Z value is generally taken as 1).

The gas phase mass spectrometer measures the particle mass, which can give the monoisotopic mass of the characteristic ion of the detected compound, which is its unique feature. The high-resolution mass spectrometer measures the exact mass of ions, and can obtain the elemental composition and empirical formula of molecules and ions. When the gas phase mass spectrometer detects unknown compounds, since the impurities will affect the mass spectrum of the sample, it is not conducive to the analysis of the mass spectrum, so the impurity composition in the detection sample is required to be extremely low. Before performing mass spectrometry, the gas chromatograph can effectively separate the mixture and obtain a sample with high purity, which meets the requirements for the sample identified by mass spectrometry.

Step 6: Carry out fault diagnosis on the internal insulation condition of the switchgear according to the test results:

If the detected SF ₆ gas insulated switchgear decomposed during the operation process contains the highest SOF ₂ content in the decomposed gas and two products of S ₂ F ₁₀ and S ₂ OF ₁₀ are detected in the decomposed gas, then the current fault type is spark discharge;

If the content of SO ₂ F ₂ and SOF ₂ in the gas decomposed during the operation of the detected SF ₆ gas insulated switchgear exceeds the set value, the current fault type is arc discharge;

If the detected content of H ₂ S and CF ₄ in the gas decomposed during the operation of SF ₆ gas insulated switchgear exceeds the set value, the current fault type is solid insulation damage.

Comparing the test results with Table 2, the type of internal insulation fault of SF ₆ gas insulated switchgear can be deduced conveniently and quickly.

Table 2 Comparison table of decomposition products and fault types

Finally, it should be noted that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of this application.

Claims (6)

1. A kind of 1. SF₆Gas-insulated switchgear built-in electrical insulation trouble-shooter, it is characterised in that including：

   To SF₆SO caused by being decomposed in gas-insulated switchgear running₂Detected with HF and correct electrochemical sensor Middle SO₂, HF gas component testing results gas detecting tube；

   Detect SF₆SO caused by being decomposed in gas-insulated switchgear running₂、H₂S, CO and HF gas components content Electrochemical sensor；

   To SF₆CF caused by being decomposed in gas-insulated switchgear running₄、SF₆、SO₂F₂、SOF₂、H₂O、S₂F₁₀And S₂OF₁₀The gas chromatograph demarcated of concentration；

   The gaseous mass analyzer being modified to the concentration of gas chromatograph demarcation；

   SF is carried out according to the concentration of gaseous mass analyzer amendment₆The computer of gas-insulated switchgear built-in electrical insulation fault diagnosis；

   The output end of electrochemical sensor, the output end of gas chromatograph, the output end of gaseous mass analyzer are connected to computer.
2. 2. device according to claim 1, it is characterised in that the gas detecting tube, including：It is passed through gas to be detected Glass tube (1)；The internal both sides of glass tube (1) are provided with tamper (2), the space between tamper (2) as reaction compartment, Glass tube (1) outer wall sets scale (4), and part corresponding with scale (4) scribbles indicator (3) in reaction compartment, to be detected Gas enters in reaction compartment in glass tube (1) by the tamper (2) of side makes finger with indicator (3) generation chemical reaction Show that agent (3) color changes, the length that indicator (3) color changes is read by scale (4) and obtains SO₂Concentration Or HF concentration.
3. 3. device according to claim 2, it is characterised in that the indicator (3) is NaOH and iodine.
4. 4. device according to claim 1, it is characterised in that the electrochemical sensor is to be detected after other according to being passed through The change of semiconductor surface resistance value determines H₂S content, the content of CO gases.
5. 5. device according to claim 1, it is characterised in that the gas chromatograph using helium as carrier gas, according to Chromatographic peak in gas chromatogram is directly demarcated to each gas component, so as to obtain CF₄、SF₆、SO₂F₂、SOF₂、H₂O、 S₂F₁₀And S₂OF₁₀Content.
6. 6. the SF carried out using the device described in claim 1₆Gas-insulated switchgear built-in electrical insulation method for diagnosing faults, its It is characterised by, including：

   From SF₆Gas to be detected is obtained inside gas-insulated switchgear；

   Gas to be detected is passed through gas detecting tube, for SF₆SO caused by being decomposed in gas-insulated switchgear running₂ Detected with HF, SO₂Being reacted with the indicator in HF and gas detecting tube promotes indicator to change color, passes through color The length of change reflects corresponding material concentration, and respective concentration value is read from scale；

   Using electrochemical sensor to SO₂、H₂S, CO and HF gas components carry out quantitative detection；

   Utilize gas chromatograph while the still undetected CF of detection gas detection pipe, electrochemical sensor₄、SF₆、SO₂F₂、 SOF₂、H₂O、S₂F₁₀And S₂OF₁₀Gas component content；

   Utilize gaseous mass analyzer detection gas detection pipe, the still undetected CF of electrochemical sensor₄、SF₆、SO₂F₂、SOF₂、 SO₂、H₂O、S₂F₁₀And S₂OF₁₀Gas component content, if the gas component content detected detects not with gas chromatograph Together, then the testing result by gaseous mass analyzer is defined；

   Fault diagnosis is carried out according to testing result switching devices built-in electrical insulation situation：

   If the SF detected₆SOF in gas caused by being decomposed in gas-insulated switchgear running₂Content highest and point Detected in gas caused by solution comprising S₂F₁₀And S₂OF₁₀Two kinds of products, then current failure type is spark discharge；

   If the SF detected₆SO in gas caused by being decomposed in gas-insulated switchgear running₂F₂、SOF₂Content exceed Setting value, then current failure type is arc discharge；

   If the SF detected₆H in gas caused by being decomposed in gas-insulated switchgear running₂S、CF₄Content exceed set Definite value, then current failure type is solid insulation damage.