A Study on the Arrangement of Pressure Relief Devices in UHV Converter Transformers
The rupture and explosion of the converter transformer oil tank pose a serious threat to the safe and stable operation of the power system while the pressure relief valve protects the equipment by releasing overpressure during an arcing fault.By analyzing the mechanism of gas bubble pulsation during the fault period,a theoretical model and its numerical calculation method for the action conditions of the pressure relief valve,the increase of oil pressure due to internal arcing faults in the converter transformer are established.Simulations are performed on an actual 500 kV ultra-high voltage converter transformer,and characteristics of faulty oil pressure variations under different pressure relief valve arrangements are obtained.The simulation results suggest that when an internal arc fault occurs in the converter transformer,the internal fault oil pressure is unevenly distributed in space;and the arrangement of the pressure relief valves has a more significant impact on the pressure relief in the vicinity of their mounting position and a lesser effect on overpressure in other positions.The simulation results also show that optimizing locations of pressure relief valves in the converter transformer can effectively reduce the peak oil pressure during the arcing fault.
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