Generic Modeling of a Line Commutated Converter based Multi-Terminal HVDC System for Power System Stability Studies

This paper reveals a novel approach for generic modeling of a Line Commutated Converter (LCC) based Multi-Terminal (MT) High Voltage Direct Current (HVDC) system. The model is based on the mathematical correlations and appropriate transfer functions of a point-to-point connection; an expansion to a MT system is realized by the superposition of partial currents in the Multi-Terminal topology, which is easily applicable to a configuration with a large number of terminals. Furthermore the Combined and Coordinated Control Method (CCCM) is implemented in the model and investigated. Advantages and differences in the dynamic behavior compared to standard control approaches are carried out. By comparing the generic stability model with an EMT (Electro-Magnetic-Transient) HVDC model during a startup process and a subsequent AC voltage drop the consistence of the dynamic behavior is shown.