An approximate steady-state characteristic for HVDC converters connected to alternators

This paper attempts a novel formulalion for the steady-state output dc voltage of a three-phase alternator fed HVDC converter, expressed as a function of the output dc current of the configuration. The formulation includes a detailed representation of alternator flux-linkages, and involves relevant self and mutual inductance parameters as well as the internal load angle of the machine. It is assumed that under steady-state conditions, all emf contributions by alternator damper current and the transformer emf contribution due to the alternator field current are negligible, so that only the speed emf contribution due to field current needs to be considered. For different example cases, converter characteristics generated by the new formulation are compared with results of corresponding dynamic simulation studies. The concurrence between the two is found to be far superior as compared to what exists between the conventional unit-connected converter characteristics and dynamic simulation results.