Validation of a two-time step HVDC transient stability simulation model including detailed HVDC controls and DC line L/R dynamics

A two-time step approach to transient stability modeling of detailed HVDC controls and L/R line dynamics is validated against a detailed electromagnetic transients model, and compared to the response-type HVDC model typically used in transient stability studies. The two-time step method combines the ability to include the detailed fast HVDC controls while still running the transient stability simulation of the large network at a 1/2 cycle time step, minimizing the impact to the overall computation time. To reduce complexity of the model, the detailed HVDC model assumes the AC commutating bus voltages to be unchanging during the internal fast time step loop of the HVDC link. Validation results show improved accuracy and numerical stability of the detailed HVDC transient stability model when compared to the typical response-type model, both in weak and strong test systems with effective short circuit ratios (ESCR) ranging from 2.0 to 5.0