Real-time Simulation of Modular Multilevel Converters

This thesis presents the real-time simulation of a realistic-size Modular Multilevel Converter (MMC) based High-Voltage Direct Current (HVDC) transmission system. Based on the concept of time-varying Thevenin equivalent, a computationally efficient model of the MMC is developed and deployed on an FPGA platform. The salient features of the developed MMC model are: (i) The decoupling of the solutions of the MMC model and the of the rest of the system, (ii) it provides an equivalent representation of the full MMC, (iii) it is suitable for parallel implementation. The model is used as part of the simulation of the 401-level France/Spain MMC-HVDC link between, in which 2 separate MMCs are included, showing the expandability of the designed system to larger DC grid scenarios. Hardware in the loop (HIL) testing capabilities of the system are also demonstrated with the addition of an external controller to the simulation system.MAS