Power Distribution

HVDC Transmission System with MMCs

This PLECS demo model shows a 320 kV, 200 MW high-voltage direct current (HVDC) transmission system with two modular multi-level converters (MMC) interconnecting two 110 kV high-voltage AC grids. MMCs are the prevalent type of voltage-source converter topology for HVDC applications. At high voltages the transmission of direct current can be more efficient than alternating current. The MMC is a bi-directional voltage source converter that interfaces high-voltage AC and DC power systems. It comprises a positive and negative arm for each of the three phases. Each arm further contains a set of switching submodules connected in series, the number of which can be chosen in this model to achieve the desired harmonic performance.

STATCOM Cascaded H-Bridge Converter

This PLECS demo model shows a medium-voltage static synchronous compensator (STATCOM) system. Converters with cascaded connections are common in high-power applications such as medium-voltage drives, high-voltage direct current (HVDC) and flexible alternating current transmission systems (FACTS). These types of converters have the advantages of low switching losses and high redundancy, but require sophisticated control, e.g., cell-capacitor voltage balancing. The STATCOM’s purpose is to compensate for the reactive power required by various loads on a power system.