KR102485072B1 - Gas sensor probe for measuring dissolved gas of transformer - Google Patents

Abstract

Disclosed is a gas sensor probe for measuring gas in oil of a transformer. The gas sensor probe for measuring gas in oil of a transformer of the present invention includes a body capable of penetrating an enclosure valve of the transformer so as to be inserted into the transformer; A sensor probe connection for inserting and fixing the body into the enclosure valve of the transformer; A gas concentration measurement unit connected to the body and capable of measuring the concentration of dissolved gas in insulating oil; a sensor control module that converts the electrical resistance data obtained from the gas concentration measurement unit into a concentration value; and a gas monitor performing analysis, statistics, control, and remote communication of the data obtained from the gas concentration measurement unit.

Description

Gas sensor probe for measuring gas in oil of transformer {GAS SENSOR PROBE FOR MEASURING DISSOLVED GAS OF TRANSFORMER}

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

In general, transformers may cause abnormal phenomena such as partial discharge and arc due to deterioration of main parts due to long-term operation, and high heat sources due to these abnormal phenomena come into contact with liquid and solid insulating materials such as insulating oil or insulating paper. In this case, gas is generated as it is deteriorated and decomposed by a chemical reaction. In this way, most of the gas generated inside the transformer has a characteristic of being dissolved in the insulating oil as it is, so by detecting it, the abnormal part, content, and serious level can be indirectly estimated.

The gas-in-oil analysis method, which analyzes the composition and concentration of gases dissolved in the insulating oil of a transformer, is an offline (off-line) method in which a sample of insulating oil sampled directly from a transformer is transported to a remote laboratory and analyzed using a complicated and expensive precision analyzer. ) method is used.

However, although this laboratory analysis method has high accuracy and reliability, it takes a long time to determine the abnormal state of the transformer, inaccuracy of the sample due to air inflow and gas outflow when sampling the insulating oil sample, and professional personnel who can handle precision analysis equipment are required. has disadvantages such as In addition, although information on the state of the transformer at a specific point in time when sampling is taken can be provided, information related to the trend of state change during a certain period between points in time cannot be obtained.

Recently, in order to improve these problems, on-line (On-line) monitoring of the transformer condition in real time using membrane, Gas Chromatography (GC), Photoacoustic Spectroscopy (PAS), and Infrared (IR) spectroscopy is used. line) method is also applied.

The online method analyzes the concentration of 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, there are problems such as the high price of tens of thousands of won to 100 million won per unit, and the high cost required not only for installation but also for maintenance.

Therefore, in recent years, interest in a simple and economical gas sensor method capable of real-time insulating oil gas analysis is rapidly increasing. Since it is still in the early stage of introduction, the application cases of gas sensors for analyzing gas in oil are limited, but electrochemical gas sensors are being used in some cases.

This gas sensor is mainly used as a 'gas monitor' method that is directly mounted on a transformer drain valve for analysis. It has a simple structure, easy installation and maintenance, and low cost.

The background art of the present invention is disclosed in Republic of Korea Patent Publication No. 10-2017-0037720 (published on April 5, 2017, gas in oil measuring device and hydraulic transformer having the same).

However, such an electrochemical (or fuel cell) gas sensor is limited to hydrogen (H ₂ ) and carbon monoxide (CO) as detectable gases, and its accuracy is significantly lower than conventional gas chromatography or photoacoustic spectroscopy methods, so it is mainly used as an alarm alarm. It is used as a role, and there are problems such as a short service life of several months due to the use of liquid electrolyte.

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

The present invention has been made to improve the above problems, and an object of the present invention according to one aspect is to insert a semiconductor gas sensor into the insulating oil inside the transformer to generate trace gases generated by abnormal conditions inside the transformer and dissolved in the insulating oil. It is to provide 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, but also accurately diagnose the contents of abnormalities, abnormal parts, and even serious levels 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 capable of penetrating an enclosure valve of the transformer so as to be inserted into the transformer; A sensor probe connection for inserting and fixing the body into the enclosure valve of the transformer; A gas concentration measurement unit connected to the body and capable of measuring the concentration of dissolved gas in insulating oil; a sensor control module that converts the electrical resistance data obtained from the gas concentration measurement unit into a concentration value; and a gas monitor performing analysis, statistics, control, and remote communication of the 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 in response to a specific gas; A membrane filter composed of at least one layer that blocks passage of liquid insulating oil and separates and passes dissolved gas; A sensor fixture 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 to prevent damage to the gas sensor, the hot water sensor, and the membrane filter.

In the present invention, the gas concentration measuring unit may further include an air circulation passage for maintaining an oxygen partial pressure between the gas sensor and the membrane filter at a predetermined level or higher and promoting separation of gas in oil by the membrane filter.

The present invention is characterized in that it further includes a dehumidifying device that penetrates the body and maintains the temperature and humidity of the air supplied to the tip of the gas concentration measuring unit 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 insulated wire heating, induction heating, and insulating oil bath.

In the present invention, the membrane filter is formed of at least one layer of plate-shaped filter or a plurality of hollow fiber membranes, and is characterized in that it is treated with an oleophobic surface modification so as not to get wet with insulating oil.

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

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

In the present invention, the sensor control module is characterized in that it can control the adapter PCB to a set temperature for each composition of the gas sensor, and maintains it at a constant temperature in conjunction with the measured value of the heater voltage and the temperature of the insulating oil.

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

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

A gas sensor probe for measuring gas in oil of a transformer according to an aspect of the present invention inserts a semiconductor type (or resistance change type) gas sensor into the insulating oil inside the transformer to generate trace gases generated by abnormal conditions inside the transformer and 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 increase the accuracy of gas concentration measurement and diagnosis, including the contents of the abnormality, the abnormal part and the serious 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 according to an embodiment of the present invention is inserted into and fastened to a valve of a transformer enclosure using a sensor probe connection part.
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 into and fastened to a valve of a transformer enclosure 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 and a sensor probe connection part are coupled to each other for measuring gas in oil of a transformer according to an embodiment of the present invention.
4 is a three-dimensional schematic diagram illustrating the internal structure and assembly state 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 an assembled state of an adapter PCB inside a sensor holder and a position of a hole provided on a side surface of a 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 lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, 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 a user or operator. Therefore, definitions of these terms will have to 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 into and fastened into a valve of a transformer enclosure using a sensor probe connection part, and FIG. It is a three-dimensional schematic diagram explaining 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 into and fastened into a valve of a transformer enclosure using a sensor probe connection, and FIG. 3 is an embodiment of the present invention. A three-dimensional schematic diagram illustrating a state in which a body and a sensor probe connection part of a gas sensor probe for measuring gas in oil of a transformer according to an example are coupled to each other, and FIG. 4 is a gas for measuring gas in oil of a transformer according to an embodiment of the present invention. It is a three-dimensional schematic diagram explaining the internal structure and assembly state of the sensor probe body, 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. Figure 6 is a three-dimensional schematic diagram explaining the assembly state of the main parts, such as, Fig. 6 is a gas sensor probe for measuring gas in oil of a transformer according to an embodiment of the present invention, the assembly state of the adapter PCB inside the sensor holder and the hole provided on the side It is a 3D schematic diagram explaining the position of the hole.

As shown in FIGS. 1 to 6, the gas sensor probe for measuring gas in oil of a pressurizer according to an embodiment of the present invention is a flange type sensor probe connection part 20 fastened to the drain valve 10 of a transformer enclosure. After that, 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 path, and various electrical wires therein, and penetrates the drain valve 10 and is inserted into the transformer.

If the body 30 is inserted too deeply beyond the inner wall of the transformer, the electromagnetic field inside the transformer can be focused and dangerous. Therefore, a locking jaw may be provided on the surface of the body 30 so that it can be inserted only up to the inner wall, 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 .

Depending on the transformer model, the sensor probe connection part 20 may be of a screw type rather than a flange type, 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 is inserted into the insulating oil inside the transformer through the inside of the sensor probe connection unit 20.

The sensor probe connection part 20 is fastened to the transformer drain valve 10 in the form of a flange or a screw, and the body 30 is inserted into a hole inside the sensor probe connection part 20 and a fixing jig 60 is used. Connect the gas monitor 50 by using At this time, it can be firmly sealed using a flange, O-ring, fixing nut and rubber gasket so that no oil leakage occurs even at a pressure of 4 bar.

In addition, the outer diameter of the body 30 inserted inside is slightly smaller than the hole diameter 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 can sample the insulating oil An insulating oil sampling opening/closing valve 70 may be added to the probe connection unit 20 to be mounted.

Inside the body 30, a boat-shaped control module holder 300 for fixing the control module board is inserted. At least one end of the control module holder 300 is in the shape of a disc, and two or more holes 422 and 432 are processed to allow passage of various wires and gas circulation fine tubes, and a socket fixing and It is mounted on a fixed pipe 310 made of metal or plastic that serves 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 fine tubes for air circulation can pass through the semicircular space between the flat plate and the curved surface 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 supplies and controls the heater voltage to maintain the substrate of the control module board at a constant temperature. have

It is common for each sensor on which the plurality of gas sensors 430 are mounted to have different material compositions and different temperatures of substrates to be heated.

Accordingly, the sensor control module maintains a predetermined temperature for each sensor substrate, so that a constant substrate temperature can be maintained at all times by controlling each heater voltage according to a change in ambient temperature.

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

The sensor holder 400 serves to mount the gas sensor 430, the membrane filter 440, and the hot water sensor, and also serves 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 location can be adjusted in various ways according to the permitted space conditions.

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 used to protect 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 to 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. additional may be applied.

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

Since the gas sensor 430 is very small, it is attached to the adapter PCB 431 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 may be variously changed 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 dissolved gas from insulating oil is mounted on the front 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 increase the effect of gas-liquid separation, two or more plate-type membrane filters can be configured to perform double or triple filtering, as well as at least one plate-type filter or a plurality of hollow fiber membranes. However, it is not limited thereto.

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

By placing the secondary protective cap 420 in front of the membrane filter 440, damage to the membrane filter 440 caused by foreign substances can be minimized.

Before and after the membrane filter 440, O-rings 402 are applied to ensure oil tightness of insulating oil and airtightness of dissolved gas, and the membrane filter 450 is used to fix the membrane filter 450 to the sensor holder 400.

A very narrow gas concentration measurement space is formed between the gas sensor 430 and the membrane filter 440, and the dissolved gas passing through the membrane filter 440 flows into this space, thereby measuring the concentration of each gas by the gas sensor 430. this becomes possible

At this time, in order to maintain a constant oxygen partial pressure and smoothly separate dissolved gas, an air circulation passage for internal and external gas circulation of the gas sensor probe may be formed on the side of the sensor holder 400 . That is, the semiconductor gas sensor requires a minimum amount of oxygen to measure the gas concentration, and since the gas sensitivity may change or malfunction may occur due to a change in the oxygen partial pressure, a gas circulation device for supplying oxygen above a certain level is separately required. 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 gas sensor is a method that measures the change in resistance of the sensor material due to the reaction between oxygen adsorbed on the surface of the sensor material and the target gas, rather than a direct reaction between the sensor material and the target gas. absolutely required

In general, insulating oil contains more than 1% (10,000 ppm) of oxygen gas dissolved in it even if it is new, so it is basically possible to measure the gas concentration without supplying oxygen separately from the outside. 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 if the amount of dissolved oxygen greatly changes due to the use of a transformer for a long time, the base resistance value of the gas sensor changes and changes occur in the gas sensitivity (R _air /R _gas ). should be able to keep

Accordingly, 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 to the ends of the air inlet and outlet so that continuous gas circulation is possible with the driving force of a micro air circulation pump, but air is supplied to maintain the temperature of the gas concentration measurement space as constant as possible. is heated by electric heating wire heating, induction heating, or water bath heating by insulating oil inside the transformer, so that air of a certain temperature or higher is supplied even in winter.

At this time, if 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. installed in principle.

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

The gas monitor 50 is connected while having a certain angle with respect to the central axis using a fixing jig 60, and an insulating oil sampling opening/closing valve 70 may be provided on the opposite side of the central axis. That is, transformer insulating oil is introduced 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 opening/closing valve 70 is connected to the sensor probe connection part ( 20), it is possible to easily sample the insulating oil when necessary.

The gas monitor 50 is in charge of data transmission and reception and control through RS232, RS422 or RS485 communication with the sensor control module and the hot water sensor, and analyzes and statistically processes the acquired information to provide remote control through international standard communication standards such as IEC 61850. Provides relevant information to the control room of In addition, a display window capable of checking basic data may be separately provided so that a substation field worker can easily check the state of the transformer.

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, and may be installed outside the gas monitor 50, such as inside the body 30 or at the end of the gas sensor probe. It can also be installed separately. The pump may be formed of a micro 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 an air circulation passage.

In addition, a separate heating and dehumidifying device such as electric heating wire heating, induction heating, or insulating oil bath may be added 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.

As such, by applying a semiconductor gas sensor using metal oxide nanomaterials, installation and operation costs are significantly reduced compared to gas chromatography and photoacoustic spectroscopy-type gas analyzers that were previously used for gas analysis in oil to monitor the state of transformers. It is possible to miniaturize with the electrochemical gas sensor, and it is advantageous for detecting hydrocarbon-based gases such as acetylene (C ₂ H ₂ ) with high reliability and significant extension of service life compared to electrochemical gas sensors. Do.

In addition, it is very easy to install and operate as it does not use complicated piping and circulation pumps for sampling insulating oil for gas-in-oil analysis. Rather than analyzing, the gas sensor is made in the form of a long probe, penetrates the inside of the drain valve, and is inserted deep into the transformer where heat flow in insulating oil is active. Gas reaction speed on the sensor surface is much faster and more accurate analysis is possible. 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 to generate an abnormal condition inside the transformer. And by detecting the composition and amount of trace gas dissolved in insulating oil, it not only checks the presence or absence of abnormalities inside the transformer, but also improves the accuracy of gas concentration measurement and diagnosis, including the contents of the abnormality, the abnormal part and the serious level, and greatly improves the reaction speed. there is.

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

The present invention has been described with reference to the embodiments shown in the drawings, but this is only exemplary, and those skilled in the art can make various modifications and equivalent other embodiments. will understand

Therefore, the true technical protection scope of the present invention should be determined by the claims below.

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

Claims (1)

a body capable of penetrating the enclosure valve of the transformer so as to be charged into the transformer;
a sensor probe connector for inserting and fixing the body into the enclosure valve of the transformer;
a gas concentration measurement unit connected to the body and capable of measuring the concentration of dissolved gas in insulating oil;
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 performing analysis, statistics, control, and remote communication of the data obtained from the gas concentration measuring unit; including,
The gas concentration measuring unit,
At least one gas sensor whose electrical characteristics change in response to a specific gas;
A membrane filter composed of at least one layer that blocks 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 preventing damage to the gas sensor, the hot water sensor, and the membrane filter; includes,
The gas concentration measuring unit further includes an air circulation passage for maintaining an oxygen partial pressure between the gas sensor and the membrane filter at a predetermined level or higher and promoting separation of gas in oil by the membrane filter,
A dehumidifying device that penetrates the body and maintains the temperature and humidity of the air supplied to the tip of the gas concentration measuring unit at a set level;
An air circulation pump for supplying oxygen in conjunction with the oxygen concentration or nitrogen concentration in the oil to the gas concentration measuring space between the gas sensor and the membrane filter of the gas concentration measuring unit; measuring gas in oil in the transformer, characterized in that it further comprises for gas sensor probes.

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