CN106503328B - Calculation and evaluation method for condensation temperature of insulating gas - Google Patents
Calculation and evaluation method for condensation temperature of insulating gas Download PDFInfo
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- CN106503328B CN106503328B CN201610913474.4A CN201610913474A CN106503328B CN 106503328 B CN106503328 B CN 106503328B CN 201610913474 A CN201610913474 A CN 201610913474A CN 106503328 B CN106503328 B CN 106503328B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/02—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering
- G01N25/12—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering of critical point; of other phase change
Abstract
The invention relates to a method for calculating and evaluating the condensation temperature of insulating gas, which mainly comprises the following steps: firstly, recording a pressure value and an ambient temperature of the air chamber, and testing to obtain a moisture content value in the air chamber of the electrical equipment; substituting the recorded and tested data into a corresponding dewing temperature calculation formula according to whether the adsorbent exists in the air chamber, and calculating to obtain the dewing temperature; and finally, comparing the calculated dewing temperature with the lowest temperature of the environment where the electrical equipment is located to obtain a conclusion. Compared with the prior art, the invention has the advantages that the existence condition of the adsorbent is considered, the obtained condensation temperature is consistent with the actual value, and the maintenance plan is made more reasonable due to overhigh humidity.
Description
Technical Field
The invention relates to a method for calculating and evaluating a condensation temperature, in particular to a method for calculating and evaluating a condensation temperature of an insulating gas.
Background
The humidity (trace amount of water) of the insulating gas is one of important criteria for evaluating the state of gas-insulated equipment such as GIS. One of the hazards of excessive humidity in high-pressure equipment is: when the temperature is reduced, dew is easily formed in the equipment and flashover is caused. However, in power failure maintenance or live detection tests, some cases that the humidity of the equipment air chamber normally runs is abnormal or even too high are often found. Humidity values in high-voltage electrical equipment are strictly regulated at home and abroad, for example, the IEC60694 regulates the maximum allowable water value (400Pa, Td-5 ℃) in the equipment; when the pressure of a Siemens specified by a known GIS production plant is 0.6MPa, the control value under normal pressure is-30 ℃ (365 mu L/L); GB/T8905, GB/T50150, DL/T506, Q/GDW471, Q/GDW1186 and the like in China also make the following requirements: in the running equipment, the arc extinguishing chamber is 300 mu L/L (20 ℃) and the non-arc extinguishing chamber is 500 mu L/L (20 ℃).
When the ambient temperature is lowered, the saturated vapor pressure in any system with an excessively high humidity value is reduced, causing the water vapor in the insulating gas to become liquid, i.e., dew condensation. However, in consideration of the fact that the electric high-voltage equipment is a closed system and the absorption and desorption balance of water vapor exists in the electric high-voltage equipment, a clear calculation method for the condensation temperature in the state is not provided.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for calculating and evaluating the condensation temperature of the insulating gas.
The purpose of the invention can be realized by the following technical scheme:
a method for calculating and evaluating a dew condensation temperature of an insulating gas, the method comprising the steps of:
s1: recording the pressure value of the air chamber and the ambient temperature, and testing to obtain the water content value in the air chamber of the electrical equipment;
s2: judging whether an adsorbent exists in the air chamber, if so, substituting the data in the step S1 into an adsorbent-containing condensation temperature calculation model to calculate the condensation temperature, and executing a step S3; if no adsorbent exists, substituting the data in the step S1 into an adsorbent-free condensation temperature calculation model, calculating the condensation temperature, and executing a step S3;
s3: and comparing the calculated dew condensation temperature with the lowest temperature of the environment where the electrical equipment is located to obtain a conclusion.
The calculation model of the adsorbent-free dew condensation temperature in step S2 is:
in the formula: t' -condensation temperature in units of;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PTthe absolute pressure of the gas chamber, in MPa.
The adsorbent-containing dew condensation temperature calculation model in step S2 is:
in the formula: t is tzs-the dew formation temperature is converted to a temperature in units of K;
Tt-ambient temperature at test in units of K;
t-ambient temperature at the time of testing, in units of ℃;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PTthe absolute pressure of the gas chamber is in MPa.
The method for evaluating the dew temperature in step S3 is:
if the dew condensation temperature is higher than the lowest environment temperature, the equipment has a dew condensation risk, and if the dew condensation temperature is lower than the lowest environment temperature, the equipment has no dew condensation risk.
The electrical equipment described in step S1 includes using SF6The gas insulated switch GIS, the novel high-voltage switch equipment HGIS, the transformer and the mutual inductor which are used as insulating media, and the GIS and the HGIS which use air, nitrogen, carbon tetrafluoride and methyl iodide as the insulating media.
The method for measuring the moisture content value in the air chamber of the electrical equipment comprises a mirror surface method and a resistance-capacitance method.
The environment temperature in the testing process is 5-35 ℃, the measuring range of the thermometer used for recording the temperature is-40-60 ℃, and the precision is 0.1 ℃.
The relative humidity of the test procedure should be no greater than 85%.
Compared with the prior art, the invention has the following advantages:
1. the condition that the adsorbent exists in the gas chamber is fully considered, namely the condition that the moisture is in an adsorption and desorption equilibrium state in the gas chamber;
2. the actual condensation temperature of the air chamber with adsorption balance is lower than the theoretical calculation value (without adsorbent);
3. the method for evaluating the abnormal or overhigh humidity value of the insulating gas is provided, so that the maintenance plan made due to overhigh humidity is more reasonable.
Drawings
Fig. 1 is a flowchart of the method for calculating and evaluating the dew condensation temperature of the insulating gas according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
Examples
The method steps are described as follows:
a method for calculating and evaluating the dew condensation temperature of insulating gas is applied to the calculation and evaluation of the dew condensation temperature value in the gas-insulated electric power equipment. Firstly, obtaining a moisture content value (humidity value, the same below) in an air chamber of the electrical equipment through testing; then, recording the ambient temperature and the pressure of the air chamber involved in the test; substituting the data obtained by testing and recording into different dewing calculation formulas according to whether the adsorbent exists in the air chamber to obtain the dewing temperature of the air chamber; and finally, comparing the calculated dewing temperature with the lowest temperature of the environment where the electrical equipment is located. The flow chart is shown in figure 1.
Further characterization of the method steps:
the electrical apparatus includes: using SF6The gas insulated switch GIS, the novel high-voltage switch equipment HGIS, the transformer and the mutual inductor which are used as insulating media, and the GIS and the HGIS which use air, nitrogen, carbon tetrafluoride and methyl iodide as the insulating media.
The water content value in the air chamber of the equipment can be obtained by testing through a mirror method and a resistance-capacitance method, and is finally converted into an indication value with the unit of mu L/L;
the instrument using the mirror method should meet the following technical requirements: the measurement range is 0-60 ℃, and the measurement error is not more than +/-0.6 ℃;
the instrument using the resistance-capacitance method should meet the following technical requirements: the measurement range should meet 0 to-60 ℃, and the measurement error should not exceed +/-2 ℃;
the test process should be performed as follows:
1) recording the environmental temperature, humidity and pressure of a test site;
2) starting up and preheating an instrument;
3) connecting the detector to a gas sampling port of the tested electrical equipment, and checking to ensure no leakage;
4) the regulating valve is slowly opened during measurement, and the gas pressure and flow rate are carefully regulated. Keeping the measurement flow stable in the measurement process, and reading and recording the detection result after the instrument reading is stable;
5) carrying out preliminary judgment on the detection result, and carrying out retesting if necessary;
6) after the detection is finished, closing the sampling valve, disconnecting the instrument pipeline from the sampling port, and checking to ensure no leakage;
the environmental temperature of the test process is 5-35 ℃, the range of a thermometer used for recording the temperature is-40-60 ℃, and the precision is 0.1 ℃:
the relative humidity of the test procedure should be no greater than 85%;
the pressure of the air chamber is read according to a pressure gauge arranged in the air chamber, the measurement unit of the pressure gauge is converted into a pressure value taking Pa as the measurement unit no matter using MPa, bar and psi, and the unit conversion is carried out according to a formula 1. The value of the air chamber pressure obtained by reading or conversion should be retained to the 1 st bit after the decimal point.
1MPa＝10bar＝145psi＝1000kPa (1)
The adsorbent in the air chamber comprises activated alumina, soda lime, artificial zeolite, a molecular sieve and activated carbon.
And when no adsorbent exists in the air chamber, substituting the test data into a formula (2) to calculate the condensation temperature.
In the formula: t' -condensation temperature in units of;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PTthe absolute pressure of the gas chamber, in MPa. .
When the air chamber is filled with the adsorbent, the test data can be substituted into a formula (3) to calculate the condensation temperature.
In the formula: t is tzs-the dew formation temperature is converted to a temperature in units of K;
tt-ambient temperature at test in units of K;
t-ambient temperature at the time of testing, in units of ℃;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PTthe absolute pressure of the gas chamber is in MPa.
And comparing the dew condensation temperature with the lowest temperature of the environment where the electrical equipment is located, wherein if the dew condensation temperature is higher than the lowest temperature of the environment, the equipment has a dew condensation risk, and if the dew condensation temperature is lower than the environment temperature, the equipment does not have the dew condensation risk.
The lowest temperature of the environment where the electrical equipment is located can be divided into the lowest temperature of the indoor environment and the lowest temperature of the outdoor environment according to actual conditions;
the lowest temperature of the indoor environment can be obtained according to the record of a thermometer arranged in the operating environment;
the minimum temperature of the outdoor environment can be obtained according to the historical minimum temperature published by a local meteorological department.
SF is adopted for both primary and secondary bus voltage changes of a certain 220kV transformer substation6Gas insulation, gauge pressureThe humidity of the insulating gas in the gas chamber was measured at 0.45MPa using a resistance-capacitance moisture meter of Hitachi RF601, and the results are shown in Table 1.
TABLE 1 humidity test results of primary and secondary transformer chambers of a transformer substation
| Numbering | Name of air cell | Humidity (20 ℃), uL/L |
| 1 | 220kV positive bus voltage phase A | 2801 |
| 2 | 220kV positive bus voltage phase change B | 2587 |
| 3 | 220kV positive bus voltage variable C phase | 2409 |
| 4 | 220kV auxiliary bus voltage phase A | 2656 |
| 5 | 220kV auxiliary bus voltage phase-changing B | 2902 |
| 6 | 220kV auxiliary bus voltage variable C phase | 2753 |
The data in table 1 are respectively substituted into formula (2) and formula (3), and the obtained theoretical dew condensation temperature (without adsorbent) and actual dew condensation temperature (with adsorbent) are shown in table 2.
TABLE 2 calculation of dew temperature results using different dew formulas
The data in table 2 show that although the micro-water content of the pressure-variable gas chamber of the station is seriously exceeded (attention value is less than 500 muL/L), the actual dewing temperature is far lower than the ambient temperature of the equipment, and the equipment can run for more than 5 years from the discovery to the treatment defect.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (5)
1. A method for calculating and evaluating the dew condensation temperature of an insulating gas is characterized by comprising the following steps:
s1: recording the pressure value of the air chamber and the ambient temperature, and testing to obtain the water content value in the air chamber of the electrical equipment;
s2: judging whether an adsorbent exists in the air chamber, if so, substituting the data in the step S1 into an adsorbent-containing condensation temperature calculation model to calculate the condensation temperature, and executing a step S3; if no adsorbent exists, the data in the step S1 is substituted into an adsorbent-free condensation temperature calculation model, the condensation temperature is calculated, and the step S3 is executed, wherein the adsorbent-free condensation temperature calculation model is as follows:
in the formula: t' -condensation temperature in units of;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PT-the absolute pressure of the gas chamber in MPa;
the calculation model of the condensation temperature of the adsorbent comprises the following steps:
in the formula: t is tzs-the dew formation temperature is converted to a temperature in units of K;
Tt-ambient temperature at test in units of K;
t-ambient temperature at the time of testing, in units of ℃;
Xcl-volume fraction of gas humidity at ambient temperature t ℃ in μ L/L;
PT-the absolute pressure of the gas chamber in MPa;
the adsorbent in the air chamber comprises activated alumina, soda lime, artificial zeolite, a molecular sieve and activated carbon;
s3: and comparing the calculated dew condensation temperature with the lowest temperature of the environment where the electrical equipment is located to obtain a conclusion.
2. The method for calculating and evaluating the dew condensation temperature of the insulating gas according to claim 1, wherein the evaluation method of the dew condensation temperature in step S3 is:
if the dew condensation temperature is higher than the lowest environment temperature, the equipment has a dew condensation risk, and if the dew condensation temperature is lower than the lowest environment temperature, the equipment has no dew condensation risk.
3. The method for calculating and evaluating the dew condensation temperature of an insulating gas according to claim 1, wherein the measuring method of the moisture content value in the gas chamber of the electrical equipment comprises a mirror method and a resistance-capacitance method.
4. The method for calculating and evaluating the condensation temperature of the insulating gas according to claim 3, wherein the environmental temperature during the test is 5-35 ℃, the range of the thermometer used for recording the temperature is-40-60 ℃, and the precision is 0.1 ℃.
5. The method for calculating and evaluating the dew condensation temperature of an insulating gas as claimed in claim 3, wherein the relative humidity during the test is not more than 85%.
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| CN112596563B (en) * | 2020-12-02 | 2022-01-28 | 国网上海能源互联网研究院有限公司 | Method and system for self-adaptive control of air insulation gas-filled cabinet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102495179A (en) * | 2011-11-28 | 2012-06-13 | 广东电网公司电力科学研究院 | Insulating gas detection system and data management method thereof |
| CN205374411U (en) * | 2016-01-16 | 2016-07-06 | 西安北鱼智能科技有限公司 | Detection apparatus for insulating gas trace moisture content |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102495179A (en) * | 2011-11-28 | 2012-06-13 | 广东电网公司电力科学研究院 | Insulating gas detection system and data management method thereof |
| CN205374411U (en) * | 2016-01-16 | 2016-07-06 | 西安北鱼智能科技有限公司 | Detection apparatus for insulating gas trace moisture content |
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| Title |
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| SF6断路器大修装配环境的净化;吕宜光、崔玉珏;《行业应用与交流》;20140531;全文 * |
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