Effects of uncertainties in shaft mechanical parameters on maximum torsional torques in meshed networks with HVDC lines

Abstract

The paper presents analysis of the torsional torques of a turbine generator rotor system in a meshed AC network with monopolar HVDC link following symmetrical and asymmetrical faults. The emphasis of the work is on establishing the influence of uncertainties in the mechanical parameters of turbine-generator shaft system on maximum torsional torques. Three loading conditions of turbine generator are considered and different types of faults are simulated for each loading condition. A full multi stage turbine model, a four machine meshed AC network and a classical, Line Current Commutated, HVDC system model are developed in DIgSILENT Power Factory environment. Uncertainties in mechanical parameters of turbine-generator shafts are modeled using probability density functions to assess more realistically their effects on maximum torsional torques.