The necessity of GIS switch equipment room equipped with SF6 integrated on- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

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The necessity of GIS switch equipment room equipped with SF6 integrated on-line monitoring system

发布时间：2018-11-24 来源：ydlcb 浏览次数：43次

First, SF6 gas leakage online monitoring

SF6 Gas insulated Combined Electrical equipment GIS. The advantages of GIS equipment are small footprint, high reliability, strong security, and small maintenance workload. However, GIS equipment also has its shortcomings, because the internal pressure of GIS equipment exceeds 4 to 6 times the atmospheric pressure equipment, there are also certain defects in the seal design, the quality of the seal ring and the processing and assembly process of the equipment is not in place and the long-term operation, there may be gas leakage phenomenon.

SF6 gas at room temperature is a colorless, odorless, non-flammable and non-toxic inert gas, with excellent insulation properties, but under the action of arc and corona in the switching process, SF6 gas will decompose and produce highly toxic low fluorine (SF4, S2F2, SOF2, HF) compounds, which will pose a serious threat to human health. If the GIS equipment leaks, SF6 gas is often deposited in the lower part of the GIS chamber because of its heavy weight, and is mixed with highly toxic low fluorine compounds. If the amount of leakage will cause the covered space to be isolated from the air, which is characterized by hypoxia, while the harmful and highly toxic decomposition components will damage human health, and when the amount of leakage exceeds a certain value, it will affect the normal operation of GIS equipment.

Due to the harmfulness of SF6 gas, according to the special provisions of the "Electrical Safety Work Regulations" (electrical part of power plants and substations), the distribution unit room equipped with SF6 equipment must ensure that the SF6 gas concentration is less than 1000ppm, and in addition to the installation of strong ventilation devices, it must be installed with alarm oxygen meters and SF6 gas concentration detection and alarm meters.

SF6 Industry Safety Regulations:

1. Article 191 The distribution unit room and the SF6 gas laboratory equipped with SF6 equipment must be equipped with a powerful ventilation device. The air outlet should be set in the lower part of the room.

2, Article 192 In the room, when the equipment is filled with SF6 gas, the relative humidity of the surrounding environment should be ≤80%, and the ventilation system must be turned on to avoid SF6 gas leaking into the work area. The SF6 gas content in the working area air shall not exceed 1000ppm.

3. Article 196 The staff entering the SF6 distribution unit room must first ventilate for 15min and measure the SF6 gas content with a leak detector, try to avoid one person entering the SF6 distribution unit room for inspection, and no one is allowed to enter the maintenance work.

4, Article 198 Entering the SF6 distribution unit room low area or cable trench work should first test whether the oxygen content is qualified.

5, Article 199 In the low area of SF6 distribution device shall be installed to alarm oxygen meter and SF6 gas leakage alarm meter. These instruments should be tested regularly to ensure their good condition.

6, Article 203 In the event of an emergency, all ventilation systems should be opened immediately for ventilation. In the event of a rupture of the explosion-proof film of the equipment, power should be cut off and cleaned with gasoline or acetone.

Conclusion: The SF6 gas leakage online monitoring system can, according to the real-time data measured by the gas detection unit, send an automatic alarm warning when the SF6 gas leakage concentration exceeds the standard or the oxygen content is lower than the specified alarm value, and automatically control the fan operation, so as to detect and deal with SF6 gas leakage of GIS switch room equipment early. Ensure the personal safety of inspection personnel and the reliability of equipment operation.

Second, SF6 micro-water integrated online monitoring:

GIS high voltage combined electrical apparatus is an important equipment in power plants and substations. SF6 gas is a non-toxic, odorless, colorless and non-combustible synthetic gas, which has incomparable insulation characteristics and arc extinguishing ability of general dielectrics.SF6 gas The trace moisture content and density of SF6 gas are important factors to ensure the reliable operation of high voltage combined electrical appliances. Electrical equipment filled with SF6 has a small footprint, low operating noise and no fire hazard. On-line monitoring of SF6 gas has become one of the main technical measures to ensure the normal and safe operation of SF6 circuit breakers and other electrical equipment.

In the parameters of SF6 gas of the high pressure switch, the water content has a great impact on the high pressure switch, which is mainly manifested in:

1. The insulation performance of the switch caused by excessive moisture content is reduced, resulting in high voltage breakdown. Due to the decrease of insulation capacity, partial discharge is generated near the electrodes at both ends, and a long time leads to through-flashover, which directly affects the breaking performance of the high-voltage switch.

2. SF6 is decomposed by arc to form SF4+SF2+SF5+ and negative ions F2-F-SF-. The presence of water hinders the compound of the decomposition and the recovery of the strength of the medium between fractures. The service life of the high voltage switch is affected. Therefore, the moisture content of SF6 gas must be tested regularly. The power grid operation regulations mandate that the density and moisture content of SF6 gas must be tested regularly before and during the operation of the equipment, and the general requirement is to test once every six months.

3, SF6 gas moisture content detection methods include electrolysis method, condensation method and resistance capacitance method. At present, portable dew point meter is used for field detection. The dew-point meter has the following defects: The portable micro-water meter cannot monitor the trace moisture content of SF6 gas online in real time, and can only measure the micro-water content regularly. In addition, part of SF6 gas needs to be released from the GIS gas chamber during measurement, and dew point meter is used to measure the moisture content. Generally, the measurement time of dew point meter is 5-10 minutes, and the gas release flow value is 5Lmin. Each detection brings a large amount of gas release, and the test process is complicated, which is not easy to operate. It is impossible to use this method for detection. The temperature of the instrument should not be lower than the ambient temperature during testing. The storage and working temperature of the instrument is -10℃~+50℃. Due to the influence of environment and climate in northern winter and southern summer, the detection data of dew point meter is not accurate. Because each measurement requires the GIS gas room to release part of SF6 gas, it will affect the health of on-site workers and pollute the environment.

Conclusion:

By installing SF6 integrated online monitoring system for water content and pressure in GIS system, it can dynamically display the change of water content and density in each gas room, providing a reliable monitoring means to avoid excessive water content in the gas room and prevent sudden drop of pressure. Moreover, the change trend of water content and density can be obtained according to the analysis of historical data. It achieves the purpose of real-time monitoring of SF6 gas pressure and water content, and provides the safety and reliability of GIS system equipment operation.

Third, SF6 density micro-water integrated online monitoring:

1. In the Technical Guidelines for Substation Equipment Online Monitoring System issued by the State Grid Corporation on April 28, 2011, sf6 circuit breakers with voltage levels of 500kV and above or GIS with voltage levels of 220kV and above can be configured with SF6 gas pressure and humidity online monitoring devices according to needs; Uhf sensors and test interfaces for daily detection should be reserved for GIS with voltage levels of 220kV and above to meet the needs of partial discharge in-line detection in operation. If the partial discharge on line detection is abnormal, the partial discharge online monitoring device can be configured for continuous or periodic tracking monitoring as required.

2, the State Grid company has guidance documents in 2008, requiring the use of online and offline technology to monitor equipment, to achieve equipment status maintenance, eliminate the previous trouble-free annual inspection system, reduce the cost of power outage and shutdown;

3. GIS is a high-precision power transmission equipment, manual detection of SF6 moisture content will cause secondary damage to the equipment, and the cyclone flow will bring water into the equipment, and the gas will be lost and then replenalized. At the same time, SF6 gas, which is originally non-toxic, will produce highly toxic gas after GIS breaking and pulling arc, so manual detection is quite dangerous.

4, the enterprise does not have a long-term professional inspection team, no professional inspection equipment and instruments, it is difficult to ensure the safe operation of high-pressure equipment;

5, GIS failures are rare, but once the failure occurs, the consequences are very serious, the overhaul work is more complicated, the time is long, and the slightest mistake may cause the overhaul quality problems.

Therefore, due to the actual situation of production safety, personnel, instruments and equipment of enterprises, it is urgent to use GIS online monitoring system to predict the operating status of GIS in advance and refer to historical operating records to evaluate and overhaul the operating status of GIS.

GIS is an important equipment in power grid operation, and is the basis to ensure the reliability of power supply. It has the characteristics of small footprint, high reliability, easy maintenance, etc., and has been widely used at home and abroad. With the wide application of GIS equipment in power system, GIS plays a decisive role in ensuring the normal operation of power system. In order to improve the stability and automation of power system, GIS online monitoring technology has become a hot research topic at home and abroad.

GIS partial discharge online monitoring:

GIS partial discharge sensors can be divided into two types according to the installation mode: built-in and external. The built-in sensor provides higher sensitivity, but requires higher requirements for manufacturing installation. Compared with the built-in sensor, the sensitivity of the external sensor is worse, but the installation is flexible, does not affect the operation of the system, and is relatively safe, so it has been widely used.

GIS partial discharge online monitoring system can monitor the local electromagnetic wave signal leaked by GIS basin insulator in real time, and effectively detect the equipment insulation deterioration, breakdown, flashover and other serious phenomena. During the long-term operation of electrical equipment such as GIS, the insulation will gradually age due to the effects of temperature, lightning, overvoltage, and self-heating, resulting in the appearance of partial discharge images, and will gradually expand resulting in equipment insulation breakdown, resulting in malignant accidents. At present, the insulation status of GIS equipment in China is mainly through regular preventive tests and maintenance to detect whether there is insulation defect inside the equipment and prevent insulation accidents. With the development of the national economy, the society has higher and higher requirements on the reliability of power supply, and the power system is also growing. The traditional practice of periodic power outage for preventive test not only cannot meet the requirements of high reliability of the power grid, but also can not indirectly bring many economic losses during the test period, and can not truly reflect the insulation state of the equipment under live operation. It is not easy to detect the insulation defects of the equipment in the running state.

GIS partial discharge on-line monitoring system can know the equipment running status in time without power failure, and reduce the economic loss caused by power failure. Can detect insulation defects under operating voltage that cannot be detected by preventive tests; Insulation monitoring of operating equipment can be carried out at any time, hidden dangers of internal local discharge of equipment can be found, and can be accurately located, so that GIS maintenance work can be carried out in a planned way, shorten the maintenance time and save maintenance costs, thus improving the reliability of GIS operation. The results show that GIS PD online monitoring system can effectively detect PD phenomenon, which lays a foundation for in-depth analysis of PD. At the same time, it is convenient to install, moderate cost, stable work, and has great application value.

Conclusion:

1, GIS partial discharge online monitoring system collection performance is stable and reliable, high monitoring sensitivity, can be all-weather automatic monitoring GIS substation multi-point partial discharge signal changes.

2, the system monitoring software interface is friendly, can carry out multiple queries and data analysis, has early warning and fault diagnosis functions, and can query the discharge trend, convenient power plant staff and superior management for scientific monitoring.

3, through on-site operation, provide a large number of reliable data for state maintenance, but also achieved good monitoring effect, suitable for GIS substation application, has a wide range of promotion value.