Research On The Stray Loss Of The Structure In Power Transformer Under Harmonic Excitation

With the development of HVDC(High Voltage Direct Current)Transmission project,more and more electric apparatuses will be affected by the harmonic magnetic field.The loss,temperature,and noise of electric apparatus will increase greatly under harmonic magnetic field excitation,which is very harmful to its normal operation.Therefore,it's very important for researchers to measure the magnetic properties of ferromagnetic materials,calculate and make an accurate analysis of the magnetic field and loss distribution in electric apparatus under harmonic magnetic excitation,which is very important to the electromagnetic design,structure optimization of the electric apparatus and even the Grid normal operation.This article was focused on the stray field loss and magnetic flux distribution in transformer structure under sinusoidal excitation with different frequencies and harmonic field excitation.Detailed experimental study and simulation analysis were made on different typed structural components(such as copper shield?pulling board and oil tank)under sinusoidal excitation with different frequencies and harmonic field excitations.Some laws were obtained about the stray field loss,which had great significance in engineering field.Based on the TEAM(Testing Electromagnetic Analysis Methods)Problem 21Benchmark Family P21~c-EM1?P21~a-0 and P21~0-B Model,detailed researches were made on the magnetic field and loss distribution of copper plate?non-magnetic steel plate and magnetic steel plate under sinusoidal excitations with different frequencies.The further researches were made on the magnetic field and loss distribution of copper plate?non-magnetic steel plate and magnetic steel plate under harmonic field excitations.The transient field solution was adopted to solve stray loss and magnetic field distribution under harmonic field excitation.Methods were put forward that division was according to the skin depth of the material under the highest harmonic frequency excitation.The DC magnetization curve was adopted to acquire magnetic flux distribution in magnetic conducting material under harmonic magnetic field excitation.The calculated values were in good agreement with the measured values,which verified the validity of the analytical method.The analytical method and conclusions were helpful to improve the effectiveness of electromagnetic design of power transformers.