CN108007818A - A kind of SF6And SF6Mixed gas device for detecting density and method - Google Patents

Abstract

The invention relates to a device and method for detecting the density of SF ₆ and SF ₆ mixed gas. The device includes a box body, a sensor unit, a data processing unit and a data presentation unit; the output end of the sensor unit is connected to the input end of the data processing unit; the data processing The output end of the unit is connected to the input end of the data presentation unit; the data processing unit and the data presentation unit are installed in the box body, and the box body is fixedly installed on the GIS tank body. The SF ₆ and SF ₆ mixed gas density detection method, this The inventive device adopts digital display, which reduces human reading errors. The density detection indication is an important parameter reflecting the internal gas quality of the switch body. In addition to the limit protection of the alarm/blocking contact, maintenance personnel need to regularly understand the current density state and change trend , in the process of meter reading, compared with the pointer indication, the present invention avoids the influence of different angles of view of personnel on the deviation of the reading.

Description

A device and method for detecting the density of SF6 and SF6 mixed gas

technical field

The invention relates to a device and method for detecting the density of SF ₆ and SF ₆ mixed gas, belonging to the field of gas density detection.

Background technique

Pure SF ₆ (sulfur hexafluoride) gas is colorless, odorless, non-toxic and non-combustible gas at normal temperature and pressure. It has excellent insulating properties and arc extinguishing ability, and is an ideal insulating medium. With the rapid development of the power industry and the improvement of technical equipment, a large number of sulfur hexafluoride circuit breakers and fully enclosed combined electrical appliances have been continuously put into construction and operation, and the consumption of sulfur hexafluoride is increasing.

However, SF ₆ gas also has its disadvantages in application: (1) It is sensitive to the uniformity of the electric field, and its advantages can only be shown in a uniform or slightly uneven electric field; (2) SF ₆ discharged into the atmosphere The gas is difficult to degrade, exists for a long time, and has a cumulative effect on global warming; (3) The price of SF ₆ gas is relatively high, which increases the cost.

In recent years, more and more attention has been paid to the reduction of greenhouse gas emissions and environmental protection at home and abroad. In response to environmental protection requirements, major related industries are reducing the emission of sulfur hexafluoride greenhouse gases; The amount of sulfur fluoride gas should be used to promote the application of mixed insulating gases in electrical equipment, especially to promote the use of SF ₆ and N ₂ mixed insulating gases. During use, the purity of SF ₆ and N ₂ mixed insulating gases should be tested.

A large amount of SF ₆ gas is used as the insulating medium in GIS (abbreviation for gas-insulated metal-enclosed combined electrical appliances) equipment. The insulation and arc extinguishing performance of GIS equipment depends to a large extent on the density of SF ₆ gas, so it is necessary to To monitor the density of SF ₆ gas to ensure the normal operation of GIS equipment, the traditional monitoring and detection of SF ₆ gas density uses a mechanical SF ₆ density relay, which performs temperature compensation through elastic metal curved tubes or bimetallic sheets ;When the ambient temperature is at 20°C, the pointer of the mechanical SF ₆ density relay points to the pressure value of the measured gas; The deformation of the bimetal sheet corresponds to the change of the compensation pressure value, and the pointer of the mechanical SF ₆ density relay does not change with the change of temperature.

Mechanical SF ₆ density relays have the following drawbacks:

a. The temperature compensation of the mechanical SF ₆ density relay is not strictly according to the Beattie-Bridgman equation (Beattie-Bridgman) to realize the density display. Temperature compensation is carried out through elastic metal curved tubes or bimetallic strips, and the Betty-Bridgeman equation is only applicable within a certain temperature range. If the temperature is too low or too high, the mechanical SF ₆ density relay and Betty-Bridgeman There is a big difference in the Mann equation, resulting in a large error in the density value, which is far from reaching the function of detecting the density value.

b. The mechanical SF ₆ density relay elastic metal curved tube or bimetal is placed outside the GIS equipment tank, and the temperature compensation generated by it is affected by the outside air temperature, not by the temperature change of SF ₆ gas Changes, so the asynchrony of the temperature change leads to a certain error, especially under the extreme low or high temperature change, it cannot reflect the change of the SF ₆ gas density in real time.

Chinese Patent No. CN201510058436.0 Name: A low-temperature resistant digital SF ₆ relay. The relay places the sensor outside the tank of the GIS equipment, which cannot truly reflect the change of SF ₆ gas density.

Contents of the invention

The technical problem to be solved by the present invention is to provide a device and method for detecting the density of SF ₆ and SF ₆ mixed gas that accurately and real-time reflect the density change of SF ₆ gas or SF ₆ mixed gas.

The present invention adopts following technical scheme:

The SF ₆ and SF ₆ mixed gas density detection device of the present invention includes a box body, a sensor unit, a data processing unit and a data presentation unit; the output end of the sensor unit is connected to the input end of the data processing unit; the data processing unit The output end is connected with the input end of the data presentation unit; the data processing unit and the data presentation unit are installed in the box body, and the box body is fixedly installed on the GIS tank body.

The sensor unit of the _SF6 and _SF6 mixed gas density detection device of the present invention includes a temperature sensor for measuring the internal environment temperature data of the GIS tank body and a pressure sensor for measuring the internal environment pressure data of the GIS tank body, the temperature sensor and The pressure sensors are respectively fixedly installed on the inner surface of the GIS tank.

In the SF ₆ and SF ₆ mixed gas density detection device of the present invention, the output ends of the temperature sensor and the pressure sensor are respectively connected to the input ends of the data processing unit; the data presentation unit includes a data display module respectively connected to the output ends of the data processing unit and a communication module, the data display module and the communication module are respectively arranged in the box, and the communication module includes a wireless communication module and a wired communication module.

The data processing unit of the SF ₆ and SF ₆ mixed gas density detection device of the present invention is a programmable logic device, and the model of the programmable logic device is Altera EPM7032AE.

The data display module of the SF ₆ and SF ₆ mixed gas density detection device of the present invention is an LED display panel, the wired communication module adopts an aviation plug interface, and the wireless communication module is a GPRS module.

SF of the present invention _gas density detection method, adopts following steps:

Step 1. The internal temperature of the GIS tank is detected by the temperature sensor as T ₀ , and the internal pressure of the GIS tank is detected by the pressure sensor as P ₀ ;

Step 2. According to the Betty-Bridgeman equation:

p=(RTB-A)d ² +RTd

A＝73.882×10 ^-5 -5.132105×10 ^-7 d

B＝2.50695×10 ^-3 -2.12283×10 ^-6 d

R＝56.9502×10 ^-5

gives the value of the gas density _d0 ,

In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K;

Step 3: Substituting the value of gas density d ₀ calculated in step 2 and the reference temperature 293K into the Betty-Bridgman equation again, and calculating the gas pressure P at the corresponding reference temperature when the internal temperature of the GIS tank is T ₀ , we get The value of the outlet gas pressure P is SF ₆ gas density;

Step 4: Send the value of SF ₆ gas density and temperature T ₀ to the data display unit for data display, and send it to the background through the communication module.

SF _of the present invention Mixed gas density detection method, described _SF Mixed gas is SF _{and N} Mixed gas or _SF and _CF Mixed gas, detection method adopts the following steps:

Step 1. The temperature sensor detects the internal temperature T ₁ of the SF ₆ mixed gas GIS tank, and the pressure sensor detects the internal pressure P ₁ of the SF ₆ mixed gas GIS tank;

Step 2, according to Dalton's law of partial pressure, by the formula:

P ₁₁ =P ₁ C

Obtain the value of _SF gas partial pressure P ₁₁ , C is the volume ratio that _SF gas occupies in _SF gas mixture, by formula:

P ₁₂ =P ₁ (1-C)

Obtain the value of CF ₄ or N ₂ gas partial pressure P ₁₂ ;

Step 3, given the partial pressure P ₁₁ and temperature T ₁ of SF ₆ gas, according to the Betty-Bridgman equation:

p=(RTB-A)d ² +RTd

A＝73.882×10 ^-5 -5.132105×10 ^-7 d

B＝2.50695×10 ^-3 -2.12283×10 ^-6 d

R＝56.9502×10 ^-5

Get the value of SF ₆ gas partial density d ₁₁ ,

In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K;

Step 4, known CF ₄ or N ₂ gas partial pressure P ₁₂ and temperature T ₁ , according to the ideal gas equation of state:

pM=kTd

Calculate the value of CF ₄ or N ₂ gas fractional density d ₁₂ ,

In the formula, p is the pressure, unit: MPa; M is the molar mass of _CF4 or _N2 gas, unit: kg/mol; k is the ideal gas constant, unit: J/(mol*K); d is the density, unit : kg/m ³ ; T is temperature, unit is K;

Step 5. The known SF ₆ gas partial density d ₁₁ and the reference temperature 293K are resubstituted into the Betty-Bridgman equation to calculate the SF ₆ gas partial pressure P ₂₁ corresponding to the reference temperature at the time of temperature T ₁ ;

Knowing the partial density d ₁₂ of CF ₄ or N ₂ and the reference temperature 293K, resubstituting it into the ideal gas state equation, calculating the temperature T ₁ corresponding to the partial pressure P ₂₂ of CF ₄ or N ₂ gas at the reference temperature 293K, and obtaining P ₂₂ value;

Step 6. According to Dalton's law of partial pressure, the formula:

P ₂ =P ₂₁ +P ₂₂

When calculating the temperature T ₁ , the density of the SF ₆ mixed gas corresponding to the reference temperature 293K;

Step 7. Send the values of SF ₆ mixed gas density P ₂ , SF ₆ gas proportion C and temperature T ₁ to the data display unit for data display, and send them to the background through the communication module.

The positive effect of the present invention is as follows:

In the SF ₆ and SF ₆ mixed gas density device of the present invention, the temperature sensor and the pressure sensor are placed inside the GIS tank, which can truly reflect the change of the SF ₆ gas density and avoid errors caused by changes in the external environment. The wired communication module and the wireless communication module can realize the data wireless communication remote transmission function, and provide a reliable basis for future data analysis.

In the SF ₆ and SF ₆ mixed gas density detection method of the present invention, SF ₆ gas calculates the density value of SF ₆ gas strictly according to the Betty-Bridgman equation, avoiding the mechanical SF ₆ density relay if the temperature is too low or too high The displayed value differs greatly from the actual density value.

The SF ₆ and SF ₆ mixed gas density device of the present invention adopts digital display, which reduces the artificial reading error. The density detection value is an important parameter reflecting the internal gas quality of the switch body. In addition to the limit protection of the alarm/blocking contact, maintenance personnel need more Regularly understand the current density state and change trend. In the process of meter reading, compared with the pointer indication, the present invention avoids the influence of different angles of view of personnel on the deviation of the reading.

Description of drawings

Accompanying drawing 1 is the structural schematic diagram of the detection device of the present invention.

Detailed ways

Embodiment one:

The _SF gas density detection device of the present invention comprises a box body 1, a sensor unit, a data processing unit and a data presentation unit; the output end of the sensor unit is connected to the input end of the data processing unit; the output end of the data processing unit is connected to the data processing unit The input end of the presentation unit is connected; the data processing unit and the data presentation unit are installed in the box body 1, and the box body 1 is fixedly installed on the GIS tank body 2; A temperature sensor for the internal environment temperature data and a pressure sensor for measuring the internal environment pressure data of the GIS tank body 2, the output terminals of the temperature sensor and the pressure sensor are respectively connected with the input terminals of the data processing unit; the temperature sensor and the pressure sensor Fixedly installed on the inner surface of the GIS tank body 2 respectively; the data presentation unit includes a data display module and a communication module respectively connected to the output end of the data processing unit, the data display module and the communication module are respectively arranged in the box body 1, and the The communication module includes a wireless communication module and a wired communication module; the data processing unit is a programmable logic device, and the model of the programmable logic device is Altera EPM7032AE; the data display module is an LED display panel, and the wired communication module An aviation plug interface is adopted, and the wireless communication module is a GPRS module.

SF of the present invention _gas density detection method, adopts following steps:

Step 1. The temperature sensor detects the internal temperature of the GIS tank 2 as T ₀ , and the pressure sensor detects the internal pressure of the GIS tank 2 as P ₀ ;

Step 2. According to the Betty-Bridgeman equation:

p=(RTB-A)d ² +RTd

A＝73.882×10 ^-5 -5.132105×10 ^-7 d

B＝2.50695×10 ^-3 -2.12283×10 ^-6 d

R＝56.9502×10 ^-5

gives the value of the gas density _d0 ,

In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K;

Step 3, resubstituting the value of the gas density _d0 calculated in step 2 and the reference temperature 293K into the Betty-Bridgman equation to calculate the gas pressure P at the corresponding reference temperature when the internal temperature of the GIS tank 2 is _T0 , Draw the value of gas pressure P as SF ₆ gas density;

Step 4: Send the value of SF ₆ gas density and temperature T ₀ to the data display unit for data display, and send it to the background through the communication module.

Example 2:

The _SF mixed gas density detection device of the present invention comprises box body 1, sensor unit, data processing unit and data presenting unit; The output end of described sensor unit is connected with the input end of data processing unit; The output end of described data processing unit is connected with The input end of the data presentation unit is connected; the data processing unit and the data presentation unit are installed in the box body 1, and the box body 1 is fixedly installed on the GIS tank body 2; the sensor unit includes a GIS tank body for measuring 2 temperature sensors for internal environment temperature data and pressure sensors for measuring GIS tank 2 internal environment pressure data, the output terminals of the temperature sensor and the pressure sensor are respectively connected with the input terminals of the data processing unit; the temperature sensor and pressure The sensors are respectively fixedly installed on the inner surface of the GIS tank body 2; the data presentation unit includes a data display module and a communication module respectively connected to the output end of the data processing unit, and the data display module and the communication module are respectively arranged in the casing 1, The communication module includes a wireless communication module and a wired communication module; the data processing unit is a programmable logic device, and the model of the programmable logic device is Altera EPM7032AE; the data display module is an LED display panel, and the wired communication The module adopts an aviation plug interface, and the wireless communication module is a GPRS module.

SF _of the present invention Mixed gas density detection method, described _SF Mixed gas is SF _{and N} Mixed gas or _SF and _CF Mixed gas, detection method adopts the following steps:

Step 1, the temperature sensor detects the internal temperature T ₁ of the SF ₆ mixed gas GIS tank 2, and the pressure sensor detects the internal pressure P ₁ of the SF ₆ mixed gas GIS tank 2;

Step 2, according to Dalton's law of partial pressure, by the formula:

P ₁₁ =P ₁ C

Obtain the value of _SF gas partial pressure P ₁₁ , C is the volume ratio that _SF gas occupies in _SF gas mixture, by formula:

P ₁₂ =P ₁ (1-C)

Obtain the value of CF ₄ or N ₂ gas partial pressure P ₁₂ ;

The specific value of C is input into the data processing unit after being detected by the instrument;

Step 3, given the partial pressure P ₁₁ and temperature T ₁ of SF ₆ gas, according to the Betty-Bridgman equation:

p=(RTB-A)d ² +RTd

A＝73.882×10 ^-5 -5.132105×10 ^-7 d

B＝2.50695×10 ^-3 -2.12283×10 ^-6 d

R＝56.9502×10 ^-5

Get the value of SF ₆ gas partial density d ₁₁ ,

In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K;

Step 4, known CF ₄ or N ₂ gas partial pressure P ₁₂ and temperature T ₁ , according to the ideal gas equation of state:

pM=kTd

Calculate the value of CF ₄ or N ₂ gas fractional density d ₁₂ ,

In the formula, p is the pressure, unit: MPa; M is the molar mass of _CF4 or _N2 gas, unit: kg/mol; k is the ideal gas constant, unit: J/(mol*K); d is the density, unit : kg/m ³ ; T is temperature, unit is K;

Step 5. The known SF ₆ gas partial density d ₁₁ and the reference temperature 293K are resubstituted into the Betty-Bridgman equation to calculate the SF ₆ gas partial pressure P ₂₁ corresponding to the reference temperature at the time of temperature T ₁ ;

Knowing the partial density d ₁₂ of CF ₄ or N ₂ and the reference temperature 293K, resubstituting it into the ideal gas state equation, calculating the temperature T ₁ corresponding to the partial pressure P ₂₂ of CF ₄ or N ₂ gas at the reference temperature 293K, and obtaining P ₂₂ value;

Step 6. According to Dalton's law of partial pressure, the formula:

P ₂ =P ₂₁ +P ₂₂

When calculating the temperature T ₁ , the density of the SF ₆ mixed gas corresponding to the reference temperature 293K;

Step 7. Send the values of SF ₆ mixed gas density P ₂ , SF ₆ gas proportion C and temperature T ₁ to the data display unit for data display, and send them to the background through the communication module.

In the SF ₆ and SF ₆ mixed gas density device of the present invention, the temperature sensor and the pressure sensor are placed inside the GIS tank 2, which can truly reflect the change of the SF ₆ gas density and avoid errors caused by changes in the external environment. The wired communication module and the wireless communication module can realize the data wireless communication remote transmission function, and provide a reliable basis for future data analysis.

In the SF ₆ and SF ₆ mixed gas density detection method of the present invention, SF ₆ gas calculates the density value of SF ₆ gas strictly according to the Betty-Bridgman equation, avoiding the mechanical SF ₆ density relay if the temperature is too low or too high The displayed value differs greatly from the actual density value.

The SF ₆ and SF ₆ mixed gas density device of the present invention adopts digital display, which reduces the artificial reading error. The density detection value is an important parameter reflecting the internal gas quality of the switch body. In addition to the limit protection of the alarm/blocking contact, maintenance personnel need more Regularly understand the current density state and change trend. In the process of meter reading, compared with the pointer indication, the present invention avoids the influence of different angles of view of personnel on the deviation of the reading.

Finally, it is noted that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principles of the present invention shall include Within the protection scope of the present invention.

Claims (7)

1. a kind of SF ₆ and SF ₆ mixed gas density detection device, it is characterized in that it comprises casing (1), sensor unit, data processing unit and data presenting unit; The output end of described sensor unit and data processing unit input end connected; the output end of the data processing unit is connected to the input end of the data presentation unit; the data processing unit and the data presentation unit are installed in the box body (1), and the box body (1) is fixedly installed in the GIS on the tank body (2). 2. A kind of _SF6 and _SF6 mixed gas density detection device according to claim 1, it is characterized in that said sensor unit comprises the temperature sensor that is used to measure GIS tank body (2) internal environment temperature data and is used for measuring The pressure sensor for the internal environment pressure data of the GIS tank body (2), the temperature sensor and the pressure sensor are respectively fixedly installed on the inner surface of the GIS tank body (2). 3. A kind of SF according to claim ₂ and _SF Mixed gas density detection device, it is characterized in that the output end of described temperature sensor and pressure sensor is connected with the input end of data processing unit respectively; The data presentation unit includes a data display module and a communication module respectively connected to the output end of the data processing unit, the data display module and the communication module are respectively arranged in the box body (1), and the communication module includes a wireless communication module and a wired communication module. 4. A device for detecting the density of SF ₆ and SF ₆ mixed gas according to claim 3, characterized in that the data processing unit is a programmable logic device, and the model of the programmable logic device is Altera EPM7032AE. 5. A kind of SF _gas density detection device according to claim 4, it is characterized in that said data display module is an LED display panel, said wired communication module adopts an aviation plug interface, and said wireless communication module is a GPRS module. 6. a kind of SF _gas density detection method, it is characterized in that adopting following steps: Step 1, the internal temperature of the GIS tank (2) is detected by the temperature sensor as T ₀ , and the internal pressure of the GIS tank (2) is detected by the pressure sensor as P ₀ ; Step 2. According to the Betty-Bridgeman equation: p=(RTB-A)d ² +RTd A＝73.882×10 ^-5 -5.132105×10 ^-7 d B＝2.50695×10 ^-3 -2.12283×10 ^-6 d R＝56.9502×10 ^-5 gives the value of the gas density _d0 , In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K; Step 3. Substituting the value of the gas density _d0 calculated in step 2 and the reference temperature 293K into the Betty-Bridgman equation again to calculate the gas pressure corresponding to the reference temperature when the internal temperature of the GIS tank (2) is T ₀ P, draw the value of gas pressure P as SF ₆ gas density; Step 4: Send the value of SF ₆ gas density and temperature T ₀ to the data display unit for data display, and send it to the background through the communication module. 7. A _SF mixed gas density detection method, characterized in that said _SF mixed gas is SF _{and N} mixed gas or _SF and _CF mixed gas, and the detection method adopts the following steps: Step 1. The temperature sensor detects the internal temperature T ₁ of the SF ₆ mixed gas GIS tank, and the pressure sensor detects the internal pressure P ₁ of the SF ₆ mixed gas GIS tank; Step 2, according to Dalton's law of partial pressure, by the formula: P ₁₁ =P ₁ C Obtain the value of _SF gas partial pressure P ₁₁ , C is the volume ratio that _SF gas occupies in _SF gas mixture, by formula: P ₁₂ =P ₁ (1-C) Obtain the value of CF ₄ or N ₂ gas partial pressure P ₁₂ ; Step 3, given the partial pressure P ₁₁ and temperature T ₁ of SF ₆ gas, according to the Betty-Bridgman equation: p=(RTB-A)d ² +RTd A＝73.882×10 ^-5 -5.132105×10 ^-7 d B＝2.50695×10 ^-3 -2.12283×10 ^-6 d R＝56.9502×10 ^-5 Get the value of SF ₆ gas partial density d ₁₁ , In the formula: p is pressure, unit: MPa; d is density, unit: kg/m ³ ; T is temperature, unit is K; Step 4, known CF ₄ or N ₂ gas partial pressure P ₁₂ and temperature T ₁ , according to the ideal gas equation of state: pM=kTd Calculate the value of CF ₄ or N ₂ gas fractional density d ₁₂ , In the formula, p is the pressure, unit: MPa; M is the molar mass of _CF4 or _N2 gas, unit: kg/mol; k is the ideal gas constant, unit: J/(mol*K); d is the density, unit : kg/m ³ ; T is temperature, unit is K; Step 5. The known SF ₆ gas partial density d ₁₁ and the reference temperature 293K are resubstituted into the Betty-Bridgman equation to calculate the SF ₆ gas partial pressure P ₂₁ corresponding to the reference temperature at the time of temperature T ₁ ; Knowing the partial density d ₁₂ of CF ₄ or N ₂ and the reference temperature 293K, resubstituting it into the ideal gas state equation, calculating the temperature T ₁ corresponding to the partial pressure P ₂₂ of CF ₄ or N ₂ gas at the reference temperature 293K, and obtaining P ₂₂ value; Step 6. According to Dalton's law of partial pressure, the formula: P ₂ =P ₂₁ +P ₂₂ When calculating the temperature T ₁ , the density of the SF ₆ mixed gas corresponding to the reference temperature 293K; Step 7. Send the values of SF ₆ mixed gas density P ₂ , SF ₆ gas proportion C and temperature T ₁ to the data display unit for data display, and send them to the background through the communication module.