KR20220004593A - Gas sensor probe for measuring dissolved gas of transformer - Google Patents

Abstract

The present invention discloses a gas sensor probe for measuring a gas in an oil of a transformer. The gas sensor probe for measuring the gas in the oil of the transformer of the present invention comprises: a body having a shape which can pass through a transformer's enclosure valve so that the same can be charged into the inside of the transformer; a sensor probe connection for inserting and fixing the body into the transformer's enclosure valve; a gas concentration measurement unit connected to the body and capable of measuring an insulating oil dissolved gas concentration; a sensor control module for converting electrical resistance data acquired by the gas concentration measurement unit into a concentration value; and a gas monitor for performing analysis, statistics, control, and remote communication of data obtained from the gas concentration measurement unit. An objective of the present invention is to provide the gas sensor probe for measuring the gas in the oil of the transformer, which can accurately diagnose contents of abnormality, a part of the abnormality, and a level of severity.

Description

Gas sensor probe for gas-in-oil measurement of transformer

The present invention relates to a gas sensor probe for measuring gas in oil of a transformer, and more particularly, by charging a semiconductor type (or resistance change type) gas sensor into the insulating oil inside the transformer, it is generated by abnormal conditions inside the transformer and dissolved in the insulating oil It relates to a gas sensor probe for measuring gas in oil in a transformer, which can not only check the presence or absence of abnormalities inside the transformer by detecting the composition and amount of trace gas, but also accurately diagnose the contents of the abnormalities, the parts of the abnormalities, and the level of severity.

In general, main parts of a transformer are deteriorated due to long-term operation, and abnormal phenomena such as partial discharge and arcing may occur. In this case, gas is generated as it degrades and decomposes by a chemical reaction. As described above, most of the gas generated inside the transformer has the characteristic of being dissolved in the insulating oil as it is, so by detecting it, it is possible to indirectly estimate the part, content, and severity level of the abnormality.

The gas-in-oil analysis method, which analyzes the composition and concentration of gas dissolved in the insulating oil of a transformer, is an offline (off-line) analysis method that transports insulating oil samples directly sampled from the transformer to a remote laboratory and analyzes them using a complex and expensive precision analyzer. ) method is used.

However, this laboratory analysis method has high accuracy and reliability, but it takes a long time to determine the abnormal state of the transformer, and when sampling insulating oil samples, inaccuracy of samples due to air inflow and gas outflow, and professional manpower capable of handling precision analysis equipment are required. have disadvantages such as In addition, although information on the state of the transformer at a specific time point at which a sample is taken can be provided, it has a disadvantage that information related to the state change trend for a certain period between the time point and the time point cannot be known.

Recently, in order to improve these problems, on-line monitoring of transformer status in real time using membrane, gas chromatography (GC), photoacoustic spectroscopy (PAS), infrared (IR) spectroscopy, etc. line) method is also applied.

The online method analyzes the concentration of each dissolved gas composition in real time by forcibly transporting and collecting the insulating oil inside the transformer using pipes and pumps from the transformer, and shows relatively high accuracy comparable to the laboratory analysis method. However, the price per unit is high in the tens of millions to 100 million won, and there are problems such as high cost for installation as well as maintenance.

Therefore, recently, interest in a gas sensor method that is simple in structure and economical while performing real-time insulation oil gas analysis is rapidly increasing. Although the application cases of gas-in-oil analysis gas sensors are limited because they are still in the early stages of introduction, some electrochemical type gas sensors are being used.

This gas sensor is mainly used as a 'gas monitor' method that is installed directly on the transformer drain valve and analyzed.

The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2017-0037720 (published on April 5, 2017, an apparatus for measuring gas in oil and a hydraulic transformer having the same).

However, in such an electrochemical (or fuel cell) gas sensor, the detectable gas is _{limited to hydrogen (H 2} ) and carbon monoxide (CO), and the accuracy is significantly lower than that of the conventional gas chromatography or photoacoustic spectroscopy method, so it is mainly used for alarm alarms. It is used as a role, and there is a problem such as a short service life of several months due to the use of a liquid electrolyte.

In addition, it has the advantage of not having to circulate the insulating oil using a pipe or a pump by directly installing and using it on the drain valve of the transformer. There is a problem in that it is difficult to secure data reliability and fast reaction speed because it does not spread quickly.

The present invention has been devised to improve the above problems, and an object of the present invention according to one aspect is to charge a semiconductor-type gas sensor into the insulating oil inside the transformer, resulting in an abnormal condition inside the transformer, and a trace amount of gas dissolved in the insulating oil. To provide a gas sensor probe for measuring gas in oil in a transformer that can not only check the presence or absence of abnormalities inside the transformer by detecting the composition and amount of

A gas sensor probe for measuring gas-in-oil of a transformer according to an aspect of the present invention includes a body having a shape that can pass through an enclosure valve of the transformer so that it can be charged into the inside of the transformer; a sensor probe connection for inserting and fixing the body into the enclosure valve of the transformer; a gas concentration measuring unit connected to the body and capable of measuring the insulating oil dissolved gas concentration; a sensor control module that converts the electrical resistance data acquired by the gas concentration measurement unit into a concentration value; and a gas monitor for performing analysis, statistics, control, and remote communication of data obtained from the gas concentration measurement unit.

In the present invention, the gas concentration measuring unit includes: at least one gas sensor whose electrical characteristics change by reacting with a specific gas; a membrane filter comprising at least one layer that blocks the passage of liquid insulating oil and separates and passes dissolved gas; a sensor holder connected to the body to fix and protect the gas sensor and the membrane filter; a hot water sensor for measuring the temperature and moisture content of the insulating oil located in front of the gas sensor; and at least one or more protective caps for suppressing damage to the gas sensor, the hot water sensor, and the membrane filter.

In the present invention, the gas concentration measuring unit, an air circulation path for maintaining the oxygen partial pressure between the gas sensor and the membrane filter above a set level and promoting gas-in-oil separation by the membrane filter; characterized in that it further comprises.

The present invention further comprises a dehumidifying device for maintaining the temperature and humidity of the air supplied to the tip of the gas concentration measuring unit through the body at a set level.

In the present invention, the dehumidifying device is characterized in that the air circulation passage is heated by at least one of insulating wire heating, induction heating, and insulating oil bath.

In the present invention, the membrane filter is formed of at least one plate-shaped filter or a plurality of hollow fiber membranes, and is characterized in that it is subjected to oleophobic surface modification to prevent it from getting wet with insulating oil.

In the present invention, it is characterized in that it further comprises an air circulation pump for supplying oxygen to the gas concentration measuring space between the gas sensor and the membrane filter of the gas concentration measuring unit in association with the oxygen concentration or nitrogen concentration in oil.

In the present invention, the sensor control module of the gas concentration measuring unit is spaced apart from the inside of the body and is characterized in that it is provided with an adapter PCB on which the gas sensor is mounted.

In the present invention, the sensor control module can control the adapter PCB to a set temperature for each composition of the gas sensor, and maintain a constant temperature in conjunction with the measured values of the heater voltage and the insulating oil.

In the present invention, the body is characterized in that the outer diameter is smaller than the inner hole diameter of the sensor probe connection part, hot water heating by insulating oil is possible, and a control module board and an air circulation passage are provided therein.

In the present invention, the body can be inserted up to the inner wall of the transformer, and a locking jaw is provided on the body surface for maintenance and fixing of the insertion depth, and is fixed to the sensor probe connection part using a rubber gasket and a fixing nut.

Gas sensor probe for gas-in-oil measurement of a transformer according to an aspect of the present invention is generated by abnormal conditions inside the transformer by charging a semiconductor type (or resistance change type) gas sensor into the insulating oil inside the transformer, and a very small amount of gas dissolved in the insulating oil By detecting the composition and amount of the transformer, it is possible to not only check the presence or absence of abnormalities inside the transformer, but also to increase the accuracy of gas concentration measurement and diagnosis up to the contents of the abnormality, the region of the abnormality, and the severity level, and greatly improve the reaction speed.

1 is a two-dimensional schematic diagram illustrating a state in which a gas sensor probe for measuring gas in oil of a transformer is inserted into a transformer enclosure valve using a sensor probe connection part and fastened according to an embodiment of the present invention.
2 is a three-dimensional schematic diagram illustrating a state in which a gas sensor probe for measuring gas-in-oil of a transformer according to an embodiment of the present invention is inserted and fastened into a transformer enclosure valve using a sensor probe connection part.
3 is a three-dimensional schematic diagram illustrating a state in which a body of a gas sensor probe for measuring gas in oil of a transformer and a sensor probe connection part are coupled to each other according to an embodiment of the present invention.
4 is a three-dimensional schematic diagram illustrating the internal structure and assembly state of a body of a gas sensor probe for measuring gas-in-oil of a transformer according to an embodiment of the present invention.
5 is a three-dimensional schematic diagram illustrating an assembly state of main components such as a sensor and a membrane filter constituting a gas concentration measuring unit of a gas sensor probe for measuring gas in oil of a transformer according to an embodiment of the present invention.
6 is a three-dimensional schematic diagram illustrating the assembly state of the adapter PCB inside the sensor holder and the position of the hole provided on the side in the gas sensor probe for measuring gas-in-oil of a transformer according to an embodiment of the present invention.

Hereinafter, a gas sensor probe for measuring gas in oil of a transformer according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or operator. Therefore, definitions of these terms should be made based on the content throughout this specification.

1 is a two-dimensional schematic diagram illustrating a state in which a gas sensor probe for measuring gas-in-oil of a transformer according to an embodiment of the present invention is inserted and fastened into a transformer enclosure valve using a sensor probe connection part, and FIG. It is a three-dimensional schematic diagram illustrating a state in which a gas sensor probe for measuring gas in oil of a transformer is inserted and fastened into a transformer enclosure valve using a sensor probe connection part according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention A three-dimensional schematic diagram illustrating a state in which a body of a gas sensor probe for gas-in-oil measurement of a transformer and a sensor probe connection part are coupled to each other, FIG. 4 is a gas for gas-in-oil measurement of a transformer according to an embodiment of the present invention It is a three-dimensional schematic diagram illustrating the internal structure and assembly state of the body of the sensor probe, and FIG. 5 is a sensor and membrane filter constituting the gas concentration measuring unit of the gas sensor probe for measuring gas in oil of a transformer according to an embodiment of the present invention. It is a three-dimensional schematic diagram illustrating the assembly state of main components, such as, and FIG. 6 is an assembly state of the adapter PCB inside the sensor holder in the gas sensor probe for measuring gas in oil of a transformer according to an embodiment of the present invention and a hole provided on the side It is a three-dimensional schematic diagram explaining the position of a hole.

1 to 6, the gas sensor probe for measuring the gas in oil of the pressure gauge according to an embodiment of the present invention is a flange type sensor probe connection part 20 to the drain valve 10 of the transformer enclosure. Then, the body 30 is inserted into the connection part.

Here, the body 30 has a cylindrical shape, and includes a sensor control module, an air circulation passage, and various electrical wiring therein, and is inserted into the transformer through the drain valve 10 .

If the body 30 is inserted too deeply beyond the inner wall of the transformer, the electromagnetic field inside the transformer can be concentrated and dangerous. Therefore, a locking protrusion can be provided on the surface of the body 30 to allow insertion only to the inner wall position, and the body 30 is made of rubber It is fixed to the sensor probe connection part 20 by tightening the gasket and the fixing nut 80 .

The sensor probe connection part 20 may have a screw method instead of a flange method depending on the transformer model, and has a cylindrical shape with a slightly larger diameter so that the cylindrical body 30 can be inserted therein.

A gas concentration measuring unit 40 is provided at one end of the body 30 , and it penetrates the inside of the sensor probe connection unit 20 and is inserted into the insulating oil inside the transformer.

The sensor probe connection part 20 is fastened to the transformer drain valve 10 by a flange or screw method, and the body 30 is inserted into a hole inside the sensor probe connection part 20 and a fixing jig 60 is inserted. The gas monitor 50 is connected using At this time, it can be tightly sealed using a flange, O-ring, fixing nut and rubber gasket to prevent leakage even at a pressure of 4 bar.

In addition, the outer diameter of the body 30 inserted therein is slightly smaller than the diameter of the hole inside the sensor probe connection part 20 so that the insulating oil inside the transformer can flow into the space between them, and the sensor so that the insulating oil can be sampled An insulating oil sampling opening/closing valve 70 may be added to the probe connection part 20 to be mounted.

A boat-shaped control module holder 300 for fixing the control module board is inserted into the body 30 . At least one end of the control module holder 300 has a disk shape, and two or more holes 422 and 432 are machined to allow various wiring and gas circulation microtubes to pass through, and the socket of the hot water sensor is fixed and It is mounted on a fixing pipe 310 made of metal or plastic material that serves as the purpose of protecting electrical wiring.

The size and shape of the flat portion of the control module holder 300 may be determined according to the control module board. The control module board is mounted on the control module holder 300 so that microtubes for air circulation can pass through the semicircular space between the flat plate and the curved portion of the control module holder 300 .

The sensor control module converts the electrical resistance value (mΩ) measured by the gas sensor 430 into a concentration value (ppm), and functions such as supplying and controlling a heater voltage to maintain the substrate of the control module board at a constant temperature have

In general, since the material composition of each sensor on which the plurality of gas sensors 430 is mounted is different, the temperature of the substrate to be heated is also different.

Accordingly, the sensor control module maintains a predetermined temperature for each sensor substrate, and controls each heater voltage according to a change in ambient temperature to maintain a constant substrate temperature at all times.

The gas concentration measurement unit 40 is connected to the body 30, and measures the gas sensor 430 for measuring the gas-in-oil concentration, the membrane filter 440 for separating only the dissolved gas from the insulating oil, and the temperature and moisture content of the insulating oil. It may be configured to include a hot water sensor to measure.

In addition to the role of mounting the gas sensor 430 , the membrane filter 440 , and the hot water sensor, the sensor holder 400 also functions to seal the transformer insulating oil from flowing into the body 30 . The gas sensor 430 and the hot water sensor are positioned as close to each other as possible, but the direction and position can be variously adjusted according to the space conditions allowed.

To this end, in the above embodiment, the gas sensor 430 and the hot water sensor may be positioned perpendicular to each other. Since both the gas sensor 430 and the membrane filter 440 are vulnerable to mechanical shock caused by foreign substances, a primary protective cap 410 and a secondary protective cap 420 may be further included for the purpose of suppressing damage.

The primary protective cap 410 is used for the purpose of isolating the entire gas concentration measuring unit 40 from foreign substances, and the secondary protective cap 420 is for protecting the hot water sensor directly exposed to liquid insulating oil. can be applied as

The secondary protective cap 420 is fixed together with the hot water sensor in the socket 421 fixed to the holes 422 and 432 machined on one side of the sensor holder 400, and protective devices of various sizes and shapes are provided as needed. may be additionally applied.

As an example, the gas sensor 430 may include at least one semiconductor-type sensor made of a metal oxide material for measuring electrical resistance. The gas sensor 430 is not particularly limited, and may be configured by any type of sensor capable of analyzing gas-in-oil in the past.

Since the gas sensor 430 is very small, it is used by attaching it to the adapter PCB 431 in order to fix the gas sensor 430 and facilitate connection to the sensor control module. At this time, the size and shape of the adapter PCB 431 are not particularly limited, and various changes may be made in consideration of the number, method, size and shape of the gas sensors 430 .

In addition, a plurality of gas sensors 430 may be provided in an array form.

A membrane filter 440 for separating the dissolved gas from the insulating oil is mounted on the front surface of the gas sensor 430 , and any filter having a function of blocking insulating oil and passing gas in oil may be used. In order to prevent contamination and damage to the membrane and to increase the effect of gas-liquid separation, two or more plate-shaped membrane filters can be configured to filter double or triple, and can be formed of at least one plate-shaped filter or a plurality of hollow fiber membranes. However, the present invention is not limited thereto.

In addition, the membrane filter 440 may be subjected to an oleophobic surface modification treatment so that it does not get wet with the insulating oil.

By placing the secondary protective cap 420 in front of the membrane filter 440 , it is possible to suppress damage to the membrane filter 440 due to foreign substances as much as possible.

Before and after the membrane filter 440 , an O-ring 402 is applied to secure the oil-tightness of the insulating oil and the gas-tightness of the dissolved gas, and is fixed to the sensor holder 400 using the membrane fixing plate 450 .

A very narrow gas concentration measurement space is formed between the gas sensor 430 and the membrane filter 440 , and the dissolved gas that has passed through the membrane filter 440 flows into this space to measure the concentration of each gas by the gas sensor 430 . this becomes possible

In this case, an air circulation path for internal and external gas circulation of the gas sensor probe may be configured on the side of the sensor holder 400 in order to maintain a constant oxygen partial pressure and to separate dissolved gas smoothly. That is, the semiconductor-type gas sensor requires a minimum amount of oxygen to measure the gas concentration, and a gas circulating device for supplying oxygen above a certain level may be separately provided because the gas sensitivity may change or an operation failure may occur due to a change in oxygen partial pressure. can be provided

Here, the air circulation passage is installed for the purpose of supplying oxygen to the gas concentration measuring unit 40 . The semiconductor-type gas sensor measures the resistance change value of the sensor material due to the reaction between the oxygen adsorbed on the surface of the sensor material and the target gas, rather than a direct reaction between the sensor material and the gas to be measured. definitely required

Even if it is new, insulating oil contains more than 1% (10,000ppm) of oxygen gas dissolved in it. Basically, it is possible to measure the gas concentration without externally supplying oxygen. However, the oxygen partial pressure is very low for measuring trace gas concentration. Therefore, in some cases, it is necessary to separately supply oxygen from the outside.

That is, if the partial pressure of oxygen is too low or the amount of dissolved oxygen is greatly changed due to the use of a transformer for a long time, the base resistance value of the gas sensor changes and the gas sensitivity (R _air /R _gas ) changes. should be able to keep

Therefore, the holes 422 and 432 for the air inlet and outlet are formed on the side of the sensor holder 400 , but the positions are spaced as far apart as possible to facilitate air circulation in the gas concentration measuring unit 40 . An air circulation path is connected at the ends of the air inlet and outlet to enable continuous gas circulation with the driving force of the micro air circulation pump, but air is supplied to keep the temperature of the gas concentration measurement space as constant as possible. is heated by means of heating wire heating, induction heating, or hot water heating using the insulating oil inside the transformer, so that air above a certain temperature is supplied even in winter.

At this time, when air is supplied to the gas concentration measurement space between the gas sensor 430 and the membrane filter 440 and the pressure rises, it may adversely affect the inflow of dissolved gas from the insulating oil. In principle, it should be installed.

In addition, when the gas sensor 430 includes an oxygen or nitrogen gas sensor to measure the oxygen concentration in oil, by interlocking the driving voltage of the air circulation pump for gas circulation with the oxygen concentration in oil, the oxygen partial pressure in the gas concentration measurement space is It can also be configured to be kept constant.

The gas monitor 50 is connected while having a predetermined angle with respect to the central axis using a fixing jig 60 , and an insulating oil sampling on/off valve 70 may be provided on the opposite side of the central axis. That is, the transformer insulating oil flows into the sensor probe connection part 20 through the empty space between the inside of the drain valve 10 and the outside of the body 30 of the gas sensor probe, and the insulating oil sampling on/off valve 70 is connected to the sensor probe connection part ( 20), it is possible to sample an insulating oil sample easily when necessary.

The gas monitor 50 is responsible for data transmission and reception and control through RS232, RS422 or RS485 communication with the sensor control module and hot water sensor, and analyzes the acquired information and processes statistics to remote locations through international standard communication standards such as IEC 61850. It provides relevant information to the control room of In addition, a display window capable of checking basic data may be separately provided so that field workers at the substation can simply check the transformer status.

In this embodiment, the micro pump for gas circulation has been described as being installed inside the gas monitor 50, but is not limited thereto. It can also be installed separately. The pump may be made of a miniature air circulation pump, but is not limited thereto, and may be changed to various types of pumps that generate a driving force for circulating air through the air circulation passage.

In addition, in order to remove moisture in the air supplied to the gas concentration measurement space and heat the air supplied in winter to a certain temperature or higher, a separate heating and dehumidifying device such as heating wire heating, induction heating, or insulating oil bath may be added.

In this way, by applying a semiconductor gas sensor using metal oxide nanomaterials, installation and operation costs are significantly reduced compared to gas analyzers of gas chromatography and photoacoustic spectroscopy, which were used for gas-in-oil analysis for transformer condition monitoring. It is possible to miniaturize together with the electrochemical gas sensor, and it is advantageous for the detection of hydrocarbon-based gases such as _{acetylene (C 2} H ₂ ) because of its high reliability and remarkable extension of its service life and less restrictions on the detectable gas composition compared to the electrochemical gas sensor. do.

In addition, it is very easy to install and operate because it does not use complicated piping and circulation pumps for insulating oil sampling for gas-in-oil analysis. Instead of analyzing, the gas sensor is made in the form of a long probe and penetrates the drain valve and inserts it deeply into the transformer where thermal convection of insulating oil is active. do.

As described above, according to the gas sensor probe for measuring gas in oil of a transformer according to an embodiment of the present invention, a semiconductor type (or resistance change type) gas sensor is charged into the insulating oil inside the transformer, which is caused by abnormal conditions inside the transformer And by detecting the composition and amount of trace gas dissolved in insulating oil, it is possible to not only check whether there is an abnormality inside the transformer, but also to increase the accuracy of gas concentration measurement and diagnosis up to the content of the abnormality, the region of the abnormality and the severity level, and greatly improve the reaction speed. have.

Implementations described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Although discussed only in the context of a single form of implementation (eg, discussed only as a method), implementations of the discussed features may also be implemented in other forms (eg, as an apparatus or program). The apparatus may be implemented in suitable hardware, software and firmware, and the like. A method may be implemented in an apparatus such as, for example, a processor, which generally refers to a computer, a microprocessor, a processing device, including an integrated circuit or programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, portable/personal digital assistants (“PDA”) and other devices that facilitate communication of information between end-users.

Although the present invention has been described with reference to the embodiment shown in the drawings, this is merely an example, and those skilled in the art to which various modifications and equivalent other embodiments are possible. will understand

Therefore, the true technical protection scope of the present invention should be defined by the following claims.

10: drain valve 20: sensor probe connection
30: body 40: gas concentration measuring unit
50: gas monitor 60: fixing jig
70: insulating oil sampling on/off valve 80: fixing nut
300: control module holder 310: fixed tube
400: sensor holder 410: primary protective cap
420: secondary protective cap 430: gas sensor
440: membrane filter 450: membrane fixing plate

Claims (1)

a body having a shape that can pass through an enclosure valve of the transformer so as to be charged into the inside of the transformer;
a sensor probe connection part for inserting and fixing the body into the enclosure valve of the transformer;
a gas concentration measuring unit connected to the body and capable of measuring the insulating oil dissolved gas concentration;
a sensor control module for converting the electrical resistance data acquired by the gas concentration measuring unit into a concentration value; and
A gas monitor for performing analysis, statistics, control, and remote communication of data obtained from the gas concentration measurement unit; including,
The gas concentration measuring unit,
at least one or more gas sensors whose electrical characteristics are changed by reacting with a specific gas;
a membrane filter comprising at least one layer that blocks the passage of liquid insulating oil and separates and passes dissolved gas;
a sensor holder connected to the body to fix and protect the gas sensor and the membrane filter;
a hot water sensor for measuring the temperature and moisture content of the insulating oil located in front of the gas sensor; and
At least one protective cap for suppressing damage to the gas sensor, the hot water sensor, and the membrane filter; includes,
The outer diameter of the body inserted therein is smaller than the diameter of the hole inside the sensor probe connection part so that the insulating oil inside the transformer can be introduced into the space therebetween so that the insulating oil can be sampled. Insulation oil sampling on-off valve; further comprising,
The gas concentration measuring unit maintains an oxygen partial pressure between the gas sensor and the membrane filter above a set level and an air circulation path for facilitating gas-in-oil separation by the membrane filter; Gas sensor probe for gas-in-oil measurement.

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