Research On Loss And Magnetization Characteristics Of Amorphous Alloy And Silicon Steel Transformer Core Models

As the country accelerates the construction of clean,low-carbon,safe and efficient energy system,the new power system with new energy as the main body will become the trend of power grid development.With the wide use of new energy power electronic devices,flexible DC transmission devices and non-linear devices,a great deal of harmonic pollution is brought to the power grid,which has caused serious harm to power distribution system and equipment.The problem of interharmonics in power system is paid more and more attention by researchers.In this paper,on the basis of fully studying the physical mechanism of interharmonic and the experimental method of magnetic properties of power transformer,the magnetic properties of silicon steel and amorphous transformer core models under sinusoidal and interharmonic excitation are systematically researched and analyzed.And a loss separation method of core models under sinusoidal and interharmonic excitation is proposed.Then,the electromagnetic characteristics of transformer models are numerically calculated and analyzed by finite element simulation software.The main research contents are:(1)An experimental platform is established to measure the magnetic characteristics of silicon steel and amorphous transformer core models under arbitrary excitation.The magnetization,loss,noise characteristics and loss composition of core models are experimentally measured and studied under power frequency sinusoidal excitation,which provides a basis for the research on the magnetic properties of transformer cores under interharmonic conditions.(2)The excitation,loss and noise characteristics of silicon steel and amorphous transformer core models are investigated on the platform under the circumstance of interharmonic excitation.And the effects of frequencies,contents and phases of interharmonic excitation conditions on magnetic properties are compared and analyzed.The transformer core is saturated in advance with the loss increasing,which leads to a substantial decrease in the operation efficiency.In addition,a loss separation method of core model under interharmonics is proposed based on Bertotti loss separation model,which provides a feasible method for magnetic loss calculation of materials and core models under interharmonics.(3)Based on the field-circuit coupling calculation method,the three-dimensional model of transformer core is established by finite element analysis software.The distribution of magnetic flux and the loss of transformer core model are calculated under sinusoidal and interharmonic excitation respectively.Finally,compared with the experimental data,the results show the validity and accuracy of the numerical calculation model.