Inclusion of a high voltage DC-voltage source converter model in a Newton-Raphson power flow algorithm

Models for high voltage DC-voltage source converter (HVDC-VSC) controllers suitable for direct incorporation into Newton-Raphson power flow algorithms are presented. The models are developed from first principles, starting with a simple VSC model and progressing to encompass the full HVDC-VSC link model. The applied modelling approach is modular in nature and in addition to the shunt-connected voltage source model, which may be used to represent a STATCOM, a series-connected voltage source model is also developed. This enables significant modelling flexibility since by suitably combining shunt and/or series voltage sources several VSC-based flexible AC transmission system (FACTS) controller models are realised quite straightforwardly, namely the back-to-back HVDC-VSC, the full HVDC-VSC link and the unified power flow controller. Attention is focused on the HVDC-VSC models. The models are implemented into an existing OOP power flow computer program written in C++ that incorporates a wide portfolio of FACTS models. The models are tested for reliability towards the convergence and accuracy of results using several power systems with varying degrees of operational complexity and power flow control requirements.