M.Sc. Stefan Mersche
Karlsruher Institut für Technologie (KIT)
Elektrotechnisches Institut (ETI)
KIT Campus Süd
Geb. 11.10, Raum 118
|Elektrotechnik und Elektronik für Maschinenbauingenieure||Vorlesung & Übung||Wintersemester||
Quasi-Two-Level Flying-Capacitor-Converter for Medium Voltage Grid Applications
2019 IEEE Energy Conversion Congress and Exposition (ECCE)
- Datum: 29 Sept.-3 Oct. 2019
Medium voltage converters are becoming more relevant in future grid applications. Especially more wind and PV generation systems will be have to added and integrated into the grid in order to achieve the required reduction in CO2 emissions. High power generation units will be integrated into the grid at medium voltage level. Furthermore meshed MV grids will require interties based on MV converter technology. Today's standard medium voltage converters are either based on the MMC technology or us 3L/5L approaches operated at low switching frequencies and containing bulky filters. Both concepts still lead to relatively high costs and low efficiencies which are major reasons for the slow spread of power converters in medium voltage grid applications.. Future grid applications demand less distortion, higher reliability and lower costs for converter systems at each voltage level. The Quasi-Two-Level operation of the flying capacitor multilevel converter with silicone-carbide (SiC) based semiconductors is a method for achieving these requirements for medium voltage converters. This paper presents a new concept for minimizing capacitance and balancing the capacitors with fast switching semiconductors. Moreover, a novel approach for limiting the overvoltage stress caused by the Quasi-Two-Level modulation of a flying capacitor converter is presented.
Modular Multilevel Converters as Active Filters to Mitigate Low Frequency Current Harmonics in Converter Fed Grid Applications
2018 PCIM Europe, International Exhibition and Conference for Power
Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg,
- Datum: 05.07.2018
This paper describes a method to improve converter fed grid structures with Modular Multilevel Converters (MMC). In grids with decentralized energy production and bidirectional power flow, an increasing number of power electronic loads and sources make power quality an important issue to ensure grid stability. The MMC topology is highly suitable to meet the requirements of a low Total Harmonic Distortion (THD) and voltage stability due to its high quality output voltages. In combination with power line communication based on harmonic injection, MMCs compensate low frequency grid current harmonics and imbalances to improve the power quality. A standalone laboratoryscale converter-fed microgrid including low voltage MMCs shows the capability of the developed control algorithms.