Quasi-Dynamic Domain Modeling of Line-Commutated Converters with the Analytical Approach

Line-commutated converters (LCCs) are significant components of conventional high-voltage direct current (HVDC) transmission systems and distributed energy resources. Various simulation methods have been developed to model LCCs under different operational conditions. To alleviate the computational burden and realize real-time simulation, the dynamic phasor model based on generalized averaging method was established for LCCs. However, the complexity of the analytical switching function limits the flexibility of utilizing the model in different situation and there is room for improvement on accuracy. This paper derives a more accurate expression for current switching function and a more extensive expression for voltage switching function for LCC modeling. The model is developed in quasi-dynamic domain and is transformed into an algebraic quadratic companion form. A simple example system is utilized to show the accuracy of the model and a large example system is utilized to demonstrate the performance of the model under transient conditions.