Recently, the online monitoring device for sulfur hexafluoride/nitrogen mixed gas (hereinafter referred to as mixed gas) developed by China Electric Power Research Institute Co., Ltd. passed the on-site verification of experts.
It is reported that the online monitoring device for mixed gas has been in operation at the Pingdingshan 110 kV Wugang Sipo Substation since the end of 2022. It is the first application of similar devices at the substation site. Data shows that after the application of this device, the power equipment such as the substation mixed gas combination electrical appliances are in good condition, and the online real-time monitoring of the gas mixing ratio and pressure in the power equipment is realized, which ensures the safe and reliable operation of the equipment and improves the operation and maintenance level of the equipment.
In order to promote the green development of power grid equipment, in recent years, State Grid Corporation of China has promoted the use of mixed gas to replace sulfur hexafluoride as a green medium. However, changes in the gas mixing ratio or pressure in the primary equipment will affect the insulation performance of the equipment and even endanger the safety of equipment operation. Although the existing mixed gas density relay can realize gas pressure monitoring, it still requires power outage detection or on-site live detection to measure the gas mixing ratio, and the safety and monitoring efficiency are low.
Starting from 2022, China Electric Power Research Institute will take the lead in the design and development of online monitoring devices for mixed gases, apply infrared pyroelectric sensing technology to detect the gas mixing ratio, and innovatively adopt online self-calibration technology to realize real-time correction of the mixing ratio detection unit, integrate the "temperature-pressure" curve to monitor the gas pressure, and control the gas mixing ratio detection error to less than ±1.0%, and the gas pressure monitoring accuracy level reaches Level 1.0.