Analysis And Calculation Of Loss In Giant Converter Transformer

Converter transformers is an important equipment in HVDC(high voltage direct current) transmission system. it's reliability directly affect the safe operation of the entire system. With the development of the national economy, the HVDC transmission system is beginning to be developed to ultrahigh voltage and large capacity. Due to the increase of the voltage rating and capacity of converter transformer, the harmonic and leakage magnetic field are enhanced, the eddy current loss is increased. Because the loss of converter transformer, which is a important parameter of power system testing and operation, is influencing the economical efficiency and reliability of the HVDC transmission system, the analysis and calculation of converter transformer loss has a very important technical and economical significance.In this thesis, loss of giant converter transformer is mainly analysed and calculated. First, the working principle and structural characteristics are described. On this basis, No-Load loss, harmonic loss and loss due to leakage are analysed and calculated and reducing loss measures are presented. No-Load loss is calculated by factory calculating method. In order to calculate harmonic loss, harmonic waveform of 12-pulse converters is simulated, the effective values of harmonics are obtained by FFT analysis. Harmonic loss is calculated and compared by two methods. The inner leakage field of converter transformer is simulated and calculated by finite element method. Distribution of transient leakage in converter transformer and eddy current loss caused by leakage are obtained by 2D combined with 3D finite element analysis.The results in this thesis has important significance to design and manufacture of domestic UHV converter transformers , and safe operation of HVDC system.