Study on Control Strategy of Cooling System for Oil Immersed Air-cooled Transformer

The reliable operation of cooling system is a necessary condition to ensure the normal operation of transformer. In this paper, a reasonable design and accurate control strategy for the cooling system of oil immersed air-cooled transformer is proposed according to the shortcomings of the existing control methods for the cooling system. Based on the top oil temperature and load current of transformer, the winding hot spot temperature rise limit and the top oil temperature rise limit of the transformer are considered in the strategy. At the same time, the temperature constraint to the load current control and the load change rate control to the fan are increased. The strategy mainly includes the top oil temperature control module, temperature constrained load current control module and temperature constrained load change rate control module. The implementation of the control strategy can avoid insufficient cooling when the transformer is under heavy load, and excessive cooling when the load is low. The operating efficiency of the cooling system is effectively improved.