A comprehensive approach to optimal step simulation of electromagnetic-transients behavior of large HVDC

Because of its reduced calculation effort and deterministic execution time, optimal-step simulation is a prerequisite for real-time performance. However, when simulating electromagnetic-transients behavior, it introduces errors in the form of switching delays and inconsistent initial conditions In order to eliminate these errors, the present paper describes a comparison of performance (the focus of numerical simulation) of traditionally Simulation with optimal step time simulator (SOST) at large HVdc systems. Detailed simulation of HVdc converter behaviour has been modified to include eliminating switching delays and for calculating consistent initial conditions, even thought switching time may not coincide with a calculation time-step and circuit may pass through a series of simultaneous switching. Furthermore, SOST proposed a simple decoupling technique to isolated parts of the circuit where the switching occurs, in order to reduce the effort required for calculation of initial conditions.