Elimination of “Harmonic Transfer Through Converters” in VSC-Based Multiterminal DC Systems by AC/DC Decoupling

ldquoHarmonic transfer through convertersrdquo has caused waveform distortion in multiterminal dc systems based on a voltage-source converter (VSC-MTDC). The harmonic transfer can be by the positive and negative sequences or by the zero sequence. A comprehensive solution consists of decoupling the ac side from the dc side of the VSC. Such decoupling has other benefits in VSC-MTDC because disturbances on the ac side of any VSC do not propagate to other VSCs (except the VSC assigned to function as the dc Voltage Regulator). Decoupling also allows a VSC to be planned and designed independently of the other VSCs of the MTDC.