Oil-immersed Power Transformer Protection System Based On CAN Bus

Oil-immersed power transformer is widely used in electrical system as key equipment. As an important part in oil-immersed power transformer, transformer oil possesses relatively better insulation characteristic and heat-dissipating characteristic, which play an important role in oil-immersed transformer and oil-immersed equipment's running. Transformer oil decompounds gas for chemical change and volume changes for physical change caused by transformer faults, all these phenomenon foreshows the appeared or ongoing faults, to protect the transformer faults through detecting appeared gas and volume change timely.This paper states the protecting method and shortcomings of traditional transformer gas and oil-height protection. By using of sensor, micro-electronics and communication techniques, a novel method which is based on CAN bus electrical transformer gas protecting method is presented. The capacitance is modeled by software to get its characteristic. By detecting of the fault gas volume and gas generating speed, combined with oil temperature detecting to protect the corresponding fault, service life pre-estimate, oil-leakage detecting and faults diagnosis. The setting range is adjustable by user on site, and also can be manipulated through remote figure interface.The protecting function of this design replaces the gas relay and oil-height detector, and realizes the communication with upper-computer through CAN bus, which meets the demand of substation automation, and would be widely used in future.