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Abstract

The successful application of HVDC transmission links requires correct predictions of the performance of the dc link and the ac system to which it is interconnected. Whatever the system configuration, the steady-state, dynamic and transient behaviour of the associated dc and ac systems are mostly interdependent. To simulate these phenomena with digital computers, converter stations must be modelled in more detail than as simple dc sources. This thesis discusses the development and implementation of a converter model which enables the converter bridge circuits to be represented in detail and the valve ignition to be controlled in the constant current mode. The model has been added to the U.B.C. Electromagnetic Transients Program to permit simulations of the complete ac/dc system. It is used to analyze the harmonics during steady-state operation, and to compare the results with those obtained from conventional (approximate) formulae. In a transient case, the new model gives closer agreement with field measurements than the simplified model used before.