A STRUCTURE-PRESERVING ENERGY FUNCTION FOR STABILITY ANALYSIS OF AC DC SYSTEMS/

Direct stability analysis of AC/DC power systems using a structure-pre serving energy function (SPEF) is proposed in this paper. The system m odel considered retains the load buses thereby enabling the representa tion of nonlinear voltage dependent loads. The HVDC system is represen ted with the same degree of detail as is normally done in transient st ability simulation. The converter controllers can be represented by si mplified or detailed models. Two or multi-terminal DC systems can be c onsidered. The stability analysis is illustrated with a 3-machine syst em example and encouraging results have been obtained.