Dynamic Average Converter Model for MVDC Link Harmonic Analysis

Medium-voltage direct-current (MVDC) technology has been widely considered as a key enabler to generate, convert and dispense electrical power with enhanced connectivity, security and quality. However, with the significant deployment of power electronics converters with high-switching frequency in MVDC systems, accurate analysis of system dynamic behavior such as harmonic distortions have become a computationally intensive task. To address these challenge average models of converters have been proposed to facilitate faster computation. However, these models only capture the steady-state characteristics of the system. To this end, in this paper, three types of time-domain based converter models: detailed, average and switching average models are presented for harmonic studies. The suitability of the modelling fidelity in reducing substantial simulation time has been validated with a practical converter topology used for the first MVDC link in Europe. Simulation based on the switching average model is shown to provide all relevant information as obtained from the detailed switching model while consuming considerably less computation time than the latter.