The Research On Large Transformer Cooling System Technique In The Underground High Voltage Substation

With the rapid development of economy, city dimensions expand ceaselessly, urban revealed characteristics of dense population, high load density and a growing demand for electricity. In order to reduce substation area, reducing noise pollution, more and more underground substations are built in urban. Typically, underground substation transformer body placed on the ground, the radiator is placed in the ground, in order to ensure the heat dissipation efficiency. But if through the pump to increase oil pressure in transformer, transformer oils in the lift to the surface above the radiator heat, will lead to higher oil pressure within the fuel tank, fuel tank spill-prone. Therefore, with the continuous improvement of underground transformer capacity, how to reasonably transformer body transfers heat to the radiators had become important factors in restricting underground safely running. In order to adapt to the harsh urban underground transformer operational requirements, there is a need for a more reliable cooling technology for large underground transformer body heat to the radiators, then radiator heat to the air, so as to achieve the cooling requirements of the transformer.Based on the underground transformer cooling requirements, by analyzing the current underground transformer characteristics of various cooling methods, combining the actual underground transformer cooling system running situations of 220 KV substation in Shanghai people’s square, Jingan 500 KV transformer substation, Wanping 220 KV substation and zizhong 110 KV transformer substation, proposed a new way of underground transformer cooling, namely underground transformer oil/oil step-cooling method. In the aspects of main technical parameter setting, equipment requirements, inspection with control and structure layout etc. to design the underground transformer oil/oil cooling system test equipment. The test equipment according to the heat, temperature rise and transformer oil flow requirement, using Japan TADA TUFX-277 plate heat exchangers, installed on the underground transformer of Jinan 220 kV substation and tilanqiao 220 kV substation in Shanghai urban in October 2009 and March 2010 respectively, and using the method of short circuit of transformer top oil temperature rise and average temperature rise of winding temperature-rise test, experiments and actual operating results show that oil/oil step-cooling system for underground transformer meet the underground transformer cooling requirements.