Modified Dynamic Model and Small-signal Stability Analysis for LCC-HVDC Systems

Inaccuracy of modeling for line commutated converter based high voltage direct current (LCC-HVDC) systems will degrade the reliability of small-signal stability analysis results. Taking a practical project as the study system, this paper establishes a modified dynamic model by modifying the current switching function, firing angle calculation and DC voltage calculation. Then, the accuracy of the modified model is verified by a detailed electromagnetic transient (EMT) simulation. Finally, with the modified dynamic model, the impact of the control parameters and AC system strength on the small-signal stability of the overall system is investigated by adopting the eigen-analysis. The results clearly demonstrate that the modified model shows higher accuracy than the original model.