This chapter highlights the need for different models within power system analysis and indicates the specifics of high-voltage direct current (HVDC) grids with respect to modeling. Next to a reduction in the temporal description of the mathematical model, it is also commonplace to reduce the system model by focusing on a particular area or subsystem and reduce the representation of the rest of the grid or remote areas. As a result of these model reductions, different classes of power system programs and mathematical techniques have been developed to study power system interactions. When time domain simulations are of interest, a distinction is traditionally made between electromagnetic transient-type programs (EMT), electromechanical stability programs and steady-state power flow programs. The detailed nature of the EMT approach, combined with the specific characteristics of the power electronic systems, make EMT-type programs an interesting choice for developing the models for these systems. |
