Reduced Dynamic Model of The Alternate Arm Converter

The Alternate Arm Converter (AAC) is a hybrid HVDC converter that maintains low power losses while protecting against DC-side faults. This paper shows the development of a Reduced Dynamic Model (RDM) of the AAC which enables time efficient system level modelling of multi-converter HVDC systems. The methodology and equations to develop the RDM are described. The RDM is then compared directly to a full switching model of the AAC, where the accuracy and the computation times are measured. The RDM is observed to simulate almost 20 times faster than the full dynamic model. The RDM is then evaluated under normal and abnormal operating conditions using a point to point HVDC model while maintaining a good level of accuracy.