Model of a VSC HVDC terminal attached to a weak AC system

This paper presents an analytical non-linear model of the power controlling terminal of a VSC HVDC (Voltage Source Converter High Voltage Direct Current) transmission system attached to a weak (high impedance) AC network. In contrast to the standard 2 state model of a VSC, the proposed model explicitly includes the behaviour of the Phased Locked Loop and AC filter in the system. When linearised around particular operating points, the proposed model follows a rigorous PSCAD model more closely than the standard model. The proposed model is therefore more appropriate for use in control system design and analysis for VSC HVDC transmission systems attached to weak AC networks.