The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In the frame of a collaboration project within Swiss Competence Centre for Energy Research, a Multi Terminal DC pilot has been implemented. For the interaction with the medium voltage AC grid, a Modular Multilevel Converter has been designed for its features in low harmonic content, scalability, and flexibility. The control of converters in the MTDC network implements a non-dead band voltage control...
A comprehensive energy balancing concept for the Modular Multilevel Converter (MMC) under unbalanced grid conditions was proposed. Grid supporting converters need to be able to fed unbalanced grid currents; grid failures lead to unbalanced grid voltages. Both unbalanced grid conditions generate energy unbalance inside the MMC. In order to handle these critical operating points, an analytical description...
Constant random and wear-out failures of sub-modules (SM) within a Modular Multi-level Converter (MMC) are examined. Constant random failures are calculated using the binomial distribution formula, using a constant failure rate. Wear-out failures are calculated using discrete Markov chain modelling and Monte Carlo estimation, with the failure rate of a SM increasing with time. The results are compared...
A novel battery energy storage system (BESS) based on an enhanced modular multilevel converter (M2C) with the ability to switch its modules in parallel is being presented. Compared to a full-bridge M2C equipped with batteries as energy storage elements on its submodules, the losses are reduced by 20%. The raise in efficiency is thoroughly explained as well as its reliability. Its high efficiency,...
This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages...
Recently, modular multilevel conterters (MMC) are also considered for medium voltage (MV) applications, where the number of modules and the switching frequency are relatively low compared to high voltage (HV) applications. In this context, standard modulation methods can cause relatively large output voltage errors. This effect is amplified even more, if the value of the module capacitances is decreased...
Modular Multilevel Converter (MMC) topology is an interesting solution for number of medium and high voltage applications. Key advantages over another multilevel topologies include flexibility of scaling in voltage and simple implementation of redundancy. In this publication control of DC-DC MMC is discussed. Analyzed converter consists of six branches connected in double wye structure. It enables...
The stability of grid-connected modular multilevel converter (MMC) under two control strategies is studied in this paper. For this purpose, the ac-side input admittance of the MMC is derived under open- and closed-loop ac-side control strategies. The derived analytical models are used to investigate the impact of the two approaches on the stability of the MMC and detailed time-domain simulations are...
In this paper a generalized control approach for modular multilevel converters is applied to a converter connecting a three-phase and a five-phase system directly without any central DC link. This new 3 × 5 modular multilevel matrix converter offers an alternative to other multilevel converters applied to five-phase machines, but foremost acts as example to prove the generality of the control. The...
Focus is on the design and development of an auxiliary power supply converter for HVDC and FACTS applications, utilising integrated gate-commutated thyristors. Due to relatively high requirements for gate drive power and operating voltage of 2.8 kV, special measures have to be considered when designing such systems. The tapped-inductor buck converter topology was chosen as the first non-isolated conversion...
This paper investigates the benefits of using high-voltage converter cells for transmission applications. These cells employ ultrahigh-voltage SiC bipolar power semiconductors, which are optimized for low conduction losses. The Modular Multilevel Converter with half-bridge cells is used as a test case. The results indicate a reduction of converter volume and complexity, while maintaining low losses...
The energy balancing task for modular multilevel converters is solved as an optimization problem, resulting in optimized feed-forward circulating currents and common-mode voltage. In contrast to the classic approach of specifying circulating current components and common-mode voltage, a maximized subset of (transformed) arm energies are specified during optimization in order to identify optimized...
This paper introduces the fault behavior of full bridge modular multilevel converters (MMCs) considering a non-simultaneous blocking of the two half bridges in each sub-module. In order to protect IGBTs in the full bridge sub-module, both sides of a full bridge sub-module are not blocked at same time point. It is assumed that the first blocking of both sides is random in each sub-module, so there...
The AC/AC single-phase/single-phase Modular Multilevel Converter (MMC) presents very interesting features for the realization of a Medium Frequency Power Electronic Transformer for traction applications, in AC-fed or multisystem railway rolling stock, like locomotives, Electric Multiple Units (EMU), high-speed units, and so on. Aiming to maximize the output frequency of the converter, i.e. the operating...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.