Generalised extended-frequency dynamic phasor model of LCC-HVDC systems for electromagnetic transient simulations

This study introduces a new model for line-commutated converter high-voltage direct current (LCC-HVDC) systems based upon the concept of extended-frequency dynamic phasors (DPs). The proposed model is able to represent LCC-HVDC converters during normal as well as abnormal operating modes such as system imbalances and commutation failure by automatically adjusting its parameters based upon converter terminal quantity measurements. The model offers a high level of accuracy with reduced computational burden, and is suitable as a replacement for conventional switch-based models of LCC in electromagnetic transient (EMT) simulation platforms. The proposed model is thoroughly evaluated against detailed EMT simulations of the CIGRE HVDC benchmark and the IEEE 12-bus systems with an embedded LCC-HVDC link. Simulation results confirm that the proposed DP-based model retains EMT-grade accuracy even at large simulations steps. Significant acceleration ratios reaching up to an order of magnitude are observed in the simulations using the proposed model compared with conventional EMT models.