Nonlinear dynamics in HVDC systems

Voltage instability in AC power systems has been widely studied from a nonlinear dynamical system perspective. In contrast, this approach for HVDC systems is of recent origin and rudimentary, therefore much basic work in this area remains to be developed. Thus this work presents a comprehensive and fundamental analysis of the nonlinear phenomena in HVDC systems. In particular the conditions for occurrence of nonlinear phenomena are derived analytically for a basic and enhanced dynamic HVDC system models, These results consequently identify: (i) the various system and HVDC control parameters which influence the nonlinear behaviour; (ii) oscillatory instability in HVDC systems as a feasible voltage collapse mechanism; and (iii) the explicit relationship between the quasi-static and dynamic conditions for aperiodic voltage collapse.