Research Of The Arc Extinction Characteristics Of Green Gas In GIL High Speed Grounding Switch

Power industry is the pillar industry of China's economic development.In recent years,with the rapid development of China's economy,the demand for power in China has been increasing year by year.In order to meet the demand of electric power in China,the transmission modes of"west-power-to-east"and"north-power-to-south"are mainly adopted at the present stage.To solve the problem of long-distance transmission,China has actively developed and built ultra-high voltage transmission projects.When the laying overhead line or underground cable is not allowed by the harsh geographical conditions,GIL will become the ideal choice for UHV transmission.At present,the sutong extra-high voltage GIL comprehensive pipe corridor constructed by state grid corporation of China is at the world's leading level in terms of technology,which is of great significance to China's economic development and ecological harmony.Traditional GIL usually uses SF₆ as the insulating medium.Because of its good insulation and arc extinguishing performance,it is widely used in medium and high voltage electrical appliances and other equipment.However,its GWP value is 23900 times that of CO₂ gas,and the greenhouse effect problem is extremely prominent.Therefore,it is particularly important to find environmentally friendly gases that can replace SF₆.At present,a lot of researches on environmental protection gas have been carried out at home and abroad.Among them,the G3?C₄F₇N/CO₂?mixed gas proposed by Alstom has excellent insulation performance,arc extinction performance and low GWP,which has become a research hotspot.In this paper,the C₄F₇N/CO₂ mixed gas is investigated with different mixing ratios,different inflation pressures,and different opening speeds to determine the breaking characteristics of a high speed grounding switch?HSGS?to determine the optimal ratio of C₄F₇N gas.The main tasks are as follows:?1?Establish GIL high speed grounding switch electric field simulation mathematical model and two-dimensional and three-dimensional simulation calculation model.Simulate and analyze the electric field distribution in the gas chamber of the high speed grounding switch.Compare and analyze the calculation results to verify the accuracy of the calculation results.?2?According to the equations of mass conservation,momentum conservation,energy conservation,gas state,etc.,a unified equation system is constructed,a simulation mathematical model is established,a GIL high speed grounding switch airflow field simulation model is established,and the C₄F₇N/CO₂ mixed gas flow field in the high speed grounding switch is numerically simulated.Calculate and compare the pressure and airflow characteristics of C₄F₇N with different proportions in high speed grounding switch with SF₆gas.?3?Research of the arc breaking characteristics in GIL high speed grounding switch.Multi-physical coupling arc model was established to simulate the breaking process of GIL high speed grounding switch,including the flow field,pressure field and temperature field.The arc characteristics of high speed grounding switch during breaking under different mixing ratio,different inflation pressure and different opening speed were studied,and the distribution of macroscopic parameters such as temperature,pressure and density of mixed gas in the gas chamber was obtained,which provided a theoretical basis for the development of GIL high speed grounding switch.