CN108007818B - A kind of SF6 and SF6 mixed gas density detection device and method - Google Patents

Abstract

The invention relates to an SF ₆ and SF ₆ mixed gas density detection device and method. The device comprises a box body, a sensor unit, a data processing unit and a data presentation unit; the output end of the sensor unit is connected with the input end of the data processing unit; The output end of the unit is connected with the input end of the data presentation unit; the data processing unit and the data presentation unit are installed in a 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 device of the invention adopts digital display, which reduces the human reading error. The density detection and indication value is an important parameter reflecting the internal gas quality of the switch body. In addition to the limit protection of the alarm/locking contact, the maintenance personnel need to regularly understand the current density state and change trend. , In the process of meter reading, compared with pointer indication, the present invention avoids the effect of deviation on readings caused by different viewing angles of personnel.

Description

A kind of SF6 and SF6 mixed gas density detection device and method

technical field

The invention relates to a density detection device and method for 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-flammable 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 electric power industry and the improvement of the level 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 amount of sulfur hexafluoride is increasing.

However, SF ₆ gas also has its shortcomings 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 non-uniform electric field; (2) SF ₆ emitted in 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 reducing greenhouse gas emissions and protecting the environment at home and abroad. In response to environmental protection requirements, major related industries are reducing the emission of sulfur hexafluoride greenhouse gas; The amount of sulfur fluoride gas will promote the application of mixed insulating gas in electrical equipment, especially the use of SF ₆ and N ₂ mixed insulating gas. In use, the purity of SF ₆ and N ₂ mixed insulating gas should be tested.

A large amount of SF ₆ gas is used as an 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. 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 mechanical SF ₆ density relays, which are temperature compensated by elastic metal curved tubes or bimetallic sheets. ; When the ambient temperature is 20°C, the pointer of the mechanical SF ₆ density relay points to the pressure value of the gas to be measured; if the ambient temperature is not 20°C, the pressure value of the gas to be measured changes with the temperature change, and the pressure value of the measured gas changes with the elastic metal curved tube or 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 is maintained not to change with the temperature change.

Mechanical SF ₆ density relays have the following drawbacks:

a. The temperature compensation of the mechanical SF ₆ density relay is not strictly in accordance with the Beattie-Bridgman equation to achieve density display. Temperature compensation through elastic metal curved tube or bimetal, the Betty-Bridgeman equation is only applicable in a certain temperature range, if the temperature is too low or too high, the mechanical SF ₆ density relay and Betty-Bridgeman equation The Mann equation is very different, resulting in a large error in the density value, which is far from the function of detecting the density value.

b. The elastic metal curved tube or bimetallic sheet of the mechanical SF ₆ density relay is placed outside the GIS equipment tank, and the temperature compensation generated by it is changed by the influence of the outside air temperature, not by the temperature change of the SF ₆ gas. Therefore, it leads to the asynchrony of temperature change, resulting in a certain error, especially in the case of extreme low or extremely high temperature changes, it cannot reflect the change of 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 and cannot really reflect the change of SF ₆ gas density.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a density detection device and method for SF ₆ and SF ₆ mixed gas that can 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 with the input end of 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 a box body, and the box body is fixedly installed on the GIS tank body.

The sensor unit of the SF ₆ and SF ₆ mixed gas density detection device of the present invention includes a temperature sensor for measuring the ambient temperature data inside the GIS tank and a pressure sensor for measuring the ambient pressure data inside the GIS tank. The temperature sensor and The pressure sensors are respectively fixed and installed on the inner surface of the GIS tank.

The output ends of the temperature sensor and the pressure sensor of the SF ₆ and SF ₆ mixed gas density detection device of the present invention are respectively connected with the input end of the data processing unit; the data presentation unit includes a data display module respectively connected with the output end 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.

The _SF gas density detection method of the present invention adopts the following steps:

Step 1: Detecting the internal temperature of the GIS tank by a temperature sensor as T ₀ , and detecting the internal pressure of the GIS tank by a 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} × ^10-7d

B=2.50695×10 ^-3 -2.12283×10 ^-6 d

R=56.9502× ^10-5

to get the value of the gas density _d0 ,

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

Step 3. Substitute the value of the gas density d ₀ calculated in step 2 and the reference temperature 293K into the Betty-Bridgeman equation again, and calculate the gas pressure P at the corresponding reference temperature when the internal temperature of the GIS tank is T ₀ , to obtain The value of outlet gas pressure P is the density of SF ₆ gas;

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

_{The SF6} mixed gas density detection method of the present invention, the _SF6 mixed gas is a mixed gas of _SF6 and _N2 or a mixed gas of _SF6 and CF4, 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, the formula is:

P ₁₁ =P ₁ C

The value of SF ₆ gas partial pressure P ₁₁ is obtained, and C is the volume ratio of SF ₆ gas in the SF ₆ mixed gas, which is represented by the formula:

P ₁₂ =P ₁ (1-C)

_Obtain the value of CF4 or _N2 gas partial pressure _P12 ;

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

p=(RTB-A)d ² +RTd

A=73.882× ^{10-5-5.132105} × ^10-7d

B=2.50695×10 ^-3 -2.12283×10 ^-6 d

R=56.9502× ^10-5

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

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

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

pM=kTd

Calculate the value _of CF4 or _N2 gas partial density _d12 ,

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

Step 5, the known SF ₆ gas partial density d ₁₁ and the reference temperature 293K, re-substitute the Betty-Bridgeman equation, and the SF ₆ gas partial pressure P ₂₁ under the corresponding reference temperature when calculating the temperature T ₁ ;

Knowing the partial density d ₁₂ of CF ₄ or N ₂ and the reference temperature of 293K, re-substitute into the state equation of the ideal gas, and calculate the temperature T ₁ corresponding to the partial pressure P ₂₂ of CF ₄ or N ₂ gas at the reference temperature of 293K, and obtain P ₂₂ the value of;

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

P ₂ =P ₂₁ +P ₂₂

When calculating the temperature T1, it corresponds to the density _of the _SF6 mixed gas at the reference temperature of 293K;

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

The positive effects of the present invention are 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 remote transmission function of data wireless communication, and provide a reliable basis for future data analysis.

In the method for detecting the density of SF ₆ and SF ₆ mixed gas of the present invention, the density value of SF ₆ gas is calculated in strict accordance with the Betty _{-Bridgman equation, so as to avoid the mechanical SF 6 density} relay if the temperature is too low or too high. The displayed value is very different 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 human reading error, and the density detection and indication value is an important parameter reflecting the internal gas quality of the switch body. Regularly understand the current density state and change trend, and in the process of meter reading, compared with pointer indication, the present invention avoids the influence of deviations in readings caused by different viewing angles of personnel.

Description of drawings

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

Detailed ways

Example 1:

The SF ₆ gas density detection device of the present invention includes 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; the sensor unit includes a device for measuring the GIS tank body 2 A temperature sensor for internal ambient temperature data and a pressure sensor for measuring the internal ambient pressure data of the GIS tank 2, the output ends of the temperature sensor and the pressure sensor are respectively connected with the input end of the data processing unit; the temperature sensor and the pressure sensor They are respectively fixed and 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 with the output end of the data processing unit, and the data display module and the communication module are respectively arranged in the box body 1, so 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 used, and the wireless communication module is a GPRS module.

The _SF gas density detection method of the present invention adopts the following steps:

Step 1. Detecting the internal temperature of the GIS tank 2 by a temperature sensor is T ₀ , and the pressure sensor detects that the internal pressure of the GIS tank 2 is P ₀ ;

Step 2. According to the Betty-Bridgeman equation:

p=(RTB-A)d ² +RTd

A=73.882× ^{10-5-5.132105} × ^10-7d

B=2.50695×10 ^-3 -2.12283×10 ^-6 d

R=56.9502× ^10-5

to get the value of the gas density _d0 ,

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

Step 3. Re-substitute the value of the gas density d ₀ calculated in step 2 and the reference temperature 293K into the Betty-Bridgeman equation, and calculate the gas pressure P at the corresponding reference temperature when the internal temperature of the GIS tank 2 is T ₀ , The value of the gas pressure P is obtained as the SF gas density _;

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

Embodiment 2:

The SF ₆ mixed gas density detection device of the present invention includes 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 input end of the data processing unit. 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 device for measuring the GIS tank body 2 A temperature sensor for internal ambient temperature data and a pressure sensor for measuring the internal environmental pressure data of the GIS tank, the output ends of the temperature sensor and the pressure sensor are respectively connected with the input end of the data processing unit; the temperature sensor and the pressure The sensors are respectively fixed 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 with the output end of the data processing unit, and the data display module and the communication module are respectively arranged in the box body 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.

_{The SF6} mixed gas density detection method of the present invention, the _SF6 mixed gas is a mixed gas of _SF6 and _N2 or a mixed gas of _SF6 and CF4, 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 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, the formula is:

P ₁₁ =P ₁ C

The value of SF ₆ gas partial pressure P ₁₁ is obtained, and C is the volume ratio of SF ₆ gas in the SF ₆ mixed gas, which is represented by the formula:

P ₁₂ =P ₁ (1-C)

_Obtain the value of CF4 or _N2 gas partial pressure _P12 ;

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

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

p=(RTB-A)d ² +RTd

A=73.882× ^{10-5-5.132105} × ^10-7d

B=2.50695×10 ^-3 -2.12283×10 ^-6 d

R=56.9502× ^10-5

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

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

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

pM=kTd

Calculate the value _of CF4 or _N2 gas partial density _d12 ,

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

Step 5, the known SF ₆ gas partial density d ₁₁ and the reference temperature 293K, re-substitute the Betty-Bridgeman equation, and the SF ₆ gas partial pressure P ₂₁ under the corresponding reference temperature when calculating the temperature T ₁ ;

Knowing the partial density d ₁₂ of CF ₄ or N ₂ and the reference temperature of 293K, re-substitute into the state equation of the ideal gas, and calculate the temperature T ₁ corresponding to the partial pressure P ₂₂ of CF ₄ or N ₂ gas at the reference temperature of 293K, and obtain P ₂₂ the value of;

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

P ₂ =P ₂₁ +P ₂₂

When calculating the temperature T1, it corresponds to the density _of the _SF6 mixed gas at the reference temperature of 293K;

Step 7: Send the values of the SF ₆ mixed gas density P ₂ , the SF ₆ gas proportion C and the temperature T ₁ to the data presentation unit for data display, and 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 remote transmission function of data wireless communication, and provide a reliable basis for future data analysis.

In the method for detecting the density of SF ₆ and SF ₆ mixed gas of the present invention, the density value of SF ₆ gas is calculated in strict accordance with the Betty _{-Bridgman equation, so as to avoid the mechanical SF 6 density} relay if the temperature is too low or too high. The displayed value is very different 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 human reading error, and the density detection and indication value is an important parameter reflecting the internal gas quality of the switch body. Regularly understand the current density state and change trend, and in the process of meter reading, compared with pointer indication, the present invention avoids the influence of deviations in readings caused by different viewing angles of personnel.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention shall include within the protection scope of the present invention.

Claims (1)

1. SF (sulfur hexafluoride)₆The density detection method of the mixed gas is characterized in that the SF₆The mixed gas is SF₆And N₂Mixed gas of (SF)₆And CF₄The detection method of the mixed gas comprises the following steps:

step one, detecting SF by a temperature sensor₆Internal temperature T of mixed gas GIS tank₁Pressure sensor detecting SF₆Internal pressure P of mixed gas GIS tank₁；

Step two, according to the Dalton partial pressure law, the formula is as follows:

P₁₁＝P₁C

to obtain SF₆Partial pressure P of gas₁₁C is SF₆Gas in SF₆The volume ratio of the mixed gas is represented by the formula:

P₁₂＝P₁(1-C)

to obtain CF₄Or N₂Partial pressure P of gas₁₂A value of (d);

step three, knowing SF₆Partial pressure P of gas₁₁And temperature T₁According to the Betty-Bridgman equation:

p＝(RTB-A)d²+RTd

A＝73.882×10^-5-5.132105×10^-7d

B＝2.50695×10^-3-2.12283×10^-6d

R＝56.9502×10^-5

to obtain SF₆Gas partial density d₁₁The value of (a) is,

in the formula: p is pressure, unit: MPa; d is density, unit: kg/m³(ii) a T is temperature in K;

step four, known CF₄Or N₂Partial pressure P of gas₁₂And temperature T₁According to the equation of state of the ideal gas:

pM＝kTd

calculating CF₄Or N₂Gas partial density d₁₂The value of (a) is,

wherein p is pressure, unit: MPa; m is CF₄Or N₂The molar mass of the gas is kg/mol; k is the ideal gas constant, in units: j/(mol. multidot.K); d is density, unit: kg/m³(ii) a T is temperature in K;

step five, knowing SF₆Gas partial density d₁₁And calculating the temperature T by substituting the reference temperature 293K into the Betty-Bridgman equation₁Corresponding to SF at the reference temperature₆Partial pressure P of gas₂₁；

Known as CF₄Or N₂Fractional density d₁₂And calculating the temperature T by substituting the reference temperature 293K into the equation of state of the ideal gas₁Time corresponding to CF at reference temperature 293K₄Or N₂Partial pressure P of gas₂₂To obtain P₂₂A value of (d);

step six, according to the Dalton partial pressure law, the formula is as follows:

P₂＝P₂₁+P₂₂

calculating the temperature T₁Corresponding to SF at the reference temperature of 293K₆Density of the mixed gas;

step seven, mixing SF₆Density P of mixed gas₂、SF₆Gas ratio C and temperature T₁The value of (2) is transmitted to the data presentation unit for data presentation and is transmitted to the background through the communication module.

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