| Nowadays,the social economy is developing rapidly and the energy supply is becoming increasingly tense.China’s hydropower resources are abundant.Hydropower resources,with their renewability and cleanliness,make hydropower construction occupy an important position in China’s energy strategy.In recent years,China’s hydropower station construction industry has been booming.So far,the total installed capacity of hydropower has exceeded 230 million kilowatts,ranking first in the world.Due to the fact that the underground powerhouse does not occupy the ground position,the construction of the ground hydraulic structure is less interfered with,and the construction period is shorter,the large-scale hydropower station generally adopts an underground hydropower station.As the installed capacity of the hydropower station increases,the scale of the hydropower station also Correspondingly,the structure of the cavern group is complicated,and there are many engineering problems of ventilation.The Baihetan Hydropower Station under construction in China is designed with a total installed capacity of 16 million kW.It is divided into left and right bank underground power plants and is the largest underground hydropower station in the world.Its main powerhouse,main busway,main transformer tunnel and other main caverns are buried deep underground.In order to meet the ventilation organization requirements of each cavern of the groundwater power station(the main floor of each main building and the main transformer hole layer),a large number of air ducts are arranged in the wall space between the hydropower station and the wall of the rock chamber.However,due to the existence of a large number of supporting anchor cables in the wall space,the cable head is exposed in the wall space,which will cause different degrees of compression deformation of the wall wind pipe,which may affect the ventilation of the air duct.The quantity also increases the difficulty of installing the duct in the wall space,which is one of the concerns in the design process.The electric energy generated by the hydropower station is transported outward through the GIL high-voltage cable in the outlet shaft,which is to take away the heat generated by the GIL high-voltage cable and the second-class gas of sulphur hexafluoride.The GIL well adopts the ventilation mode of the lower-sending upper row,and the inlet of the lower blower is located.The sixth drainage corridor.The high-speed elevator is arranged in the outlet shaft,and the pressure relief port of the lower section of the elevator shaft is also connected to the drainage corridor,and is close to the suction port of the GIL shaft blower,and the elevator car may generate strong during high-speed movement.The piston wind,therefore,whether the piston wind generated by the elevator car operation will affect the ventilation of the GIL well is another problem of design concern.The research content of this paper mainly includes the following two aspects:(1)Analyze the structure and position of the wall wind pipe and anchor cable.In order to adapt the position of the air duct to the anchor cable and ensure that the air duct installation is not damaged,it is proposed that the air duct is “perforated” at the corresponding position of the anchor cable.The solution is to perform a partial "perforation" deformation of the duct,so there will be a large change in the duct structure.In order to verify whether the deformed air duct can meet the required air volume,a similar model test was carried out to verify the feasibility of the "perforation" scheme,and the influence of different installation positions of the wind turbine on the air volume of the system was compared.The change in air volume of the duct system at different locations.Calculate the total local drag coefficient of the system under each scheme,draw conclusions and provide theoretical support and design reference for similar engineering construction.(2)For the high-speed elevator in the outlet shaft,the theoretical analysis of the unsteady Bernoulli equation is used to derive the piston wind speed generated by the high-speed elevator movement in the line shaft,and the wind pressure at the pressure relief port is further calculated.Through the calculation of wind pressure and wind speed,using energy and mass conservation,analyze and demonstrate whether the high-speed elevator movement produces piston wind on the GIL well mechanical ventilation system. |
