Frequency scan based screening technique for harmonic interactions of HVDC systems

This paper applies frequency scanning techniques to the calculation of multi-infeed interaction factor (MIIF) at harmonic frequencies as a screening method for harmonic interactions of HVDC systems. The frequency scan technique is compared with the EMT simulations based current injection method, which is commonly used for MIIF calculations, for a set of test cases and is shown to be a faster, convenient and more accurate technique. Instead of voltage ratio based MIIF, the concept of multi-infeed energy interaction factor (MIEIF), which is based on the energy ratio is then proposed as an extension. The MIEIF is calculated in the frequency range of 10-3000Hz and plotted against frequency. The MIEIF curves can then be used as a screening method in the design of the ac filters for an HVDC link or FACTs device. MIEIF is compared with MIIF and gives a good indication of the level of harmonic interactions in cases where MIIF does not.