Dynamic Phasors Modeling of the VSC-HVDC Under Unbalanced Conditions

We established a dynamic model for VSC-HVDC systems on the basis of the dynamic phasors approach.The model was derived in a synchronous dq reference frame,and could be used to simulate the behavior of VSC-HVDC systems under unbalanced conditions.The dynamic phasors were based on the time-varying Fourier coefficient series and the established model was an approximate time-invariant large-signal model.The dynamic phasors model was more accurate than quasi-steady state model,and it was more efficient than detailed electromagnetic model.The dynamic phasors model was validated via simulation of a VSC-HVDC system under unbalanced conditions through PSCAD/EMTDC.The results show the dynamic phasors model is accurate and efficient.