400kV Single-phase Power Transformer DC Bias Magnetic Theory And Experimental Research

The modern electric power system has entered the new stage of big system,ultra-high voltage long-distance transmission and trans-regional networking.How to improve the transmission capacity of the power grid as much as possible and realize the reliability of power grid operation has always been an important research topic of power engineering.HVDC is developed to accommodate this demand.At the same time,the HVDC transmission has some influence on the power grid equipment,which needs to be studied.Transformer dc bias phenomenon is an important research topic.Geomagnetically induced current(GIC)and the HVDC ground electrode current will invade the neutral grounding transformer,transformer caused by DC bias,resulting in half wave core saturation,excitation current,high distortion produces a large number of harmonics,the transformer temperature and vibration noise increases,reactive power loss increases.Serious saturation magnetic bias will make magnetic flux in the iron core part is closed under normal circumstances leave the transformer core,metal structure loss increase,cause local overheating,insulation failure,damage to the transformer or reduce the life.This project will be the phenomenon of DC magnetic bias and electromagnetic field calculation together organically,through the four same types of 400kV(DFP-240000/400)single-phase power transformer model(the characteristics of the model are:no load voltage,low loss,strong oil circulating cooling,low noise,double winding coil arranged by the level of high-profile arrangement)test and software simulation,the main cause of DC HVDC transmission system for transformer magnetic bias effect of DC bias,variation of transformer excitation current and harmonic vibration,noise and loss,temperature rise.