Quantitative Analysis of Converter Transformer Losses Under Filter Optimization

Under actual operating conditions, the converter transformer contains a large amount of harmonics, which causes increased equipment loss and temperature rise. Different filtering methods can effectively reduce the harmonic components of the converter transformer. This paper analyzes the current harmonic characteristics under the two filtering methods of grid-side and valve-side, builds a simulation model of a real converter transformer, and compares the magnetic field, loss and temperature of the key parts of the converter transformer under the two filtering methods. The results show that under the valve-side filtering mode, the magnetic flux density of the transformer is $\mathbf{9 3. 5 \%}$ of that under the grid-side filtering mode, the maximum internal loss is reduced to 78.7% of that under the grid-side filtering mode, and the maximum internal temperature rise distribution is 93.9% of that under the grid-side filtering mode. These research results ultimately indicate that, compared with grid-side filtering, valve-side filtering has better performance in suppressing high-order harmonics, reducing magnetic flux density and losses, and lowering temperature rise.