The Modular Multilevel Converter (MMC) is a most promising converter technology for the High Voltage DC application. The complex topology of the MMC requires several additional controllers to balance the energy in the capacitors which are distributed all over the converter.

The complex topology of the Modular Multilevel Converter (MMC) requires some additional controllers to keep its functionalities. One of the important requirements on the MMC control is to balance the energy stored in the distributed capacitors in the arms on the three legs.

In this work, a novel dynamic models for MMC is proposed. The proposed models are intended to simplify modeling challenges related to the high number of switching elements in the MMC. The models can be easily used to simulate the converter for stability analysis or protection algorithms for HVDC grids.

A novel protection strategy for multi-terminal high voltage direct current (HVDC) grids based on the implementation of breaking modules (BM) with both limiting and breaking capabilities will be presented. It incorporates a resistive-type superconducting fault current limiter (SFCL) in series with a mechanical DC circuit breaker (DCCB). The proposed arrangement of BMs allows an intrinsic selective fault identification criteria based on the quenching of the SFCL. The fault current limitation reduces the breaking capability, speed and energy requirements for the DCCB. Furthermore, a continuous grid operation can be assured by adding DC inductors and capacitors, assuring a constant power flow during and after the fault event. In this paper, a primary protection scheme is conceptually described and off-line simulation studies performed in EMTP-RV® are discussed.

A Review of Modular Multi-Level Converter (MMC) Modeling for [...]