A Novel Method of Harmonic Suppression in the AC/DC Transmission System Based on Novel Converter Transformer

In the traditional AC/DC transmission system, to reduce the effect of harmonics to the AC system produced by the converter, filters and reactive power compensating equipments are installed in the primary side. This article presents a novel converter transformer and harmonic suppression scheme- filter commutated converter (FCC), which can greatly restrain the harmonic current from flowing into the AC system. The article also introduces the connection mode of windings, calculation of voltage offset angle, determination of windings turn ratio and request of windings equivalent impedance; and it analyzes the harmonic suppression principle, too. Finally, it establishes the digital simulation models of DC transmission system based on the novel converter transformer and traditional converter transformer. The simulating results of frequency spectrum of current wave indicate that the 5th , 7th , 11th and 13th harmonic components can be effectively suppressed in the valve side with FCC. Compared with the results of the traditional harmonic suppression, the reliability and feasibility of the novel converter transformer and the scheme of harmonic suppression (FCC) are testified.