Modular Multilevel Converters for HVDC Applications: Review on Converter Cells and Functionalities
TL;DR: In this article, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies for high-power dc systems, where the derived converter cells are treated as building blocks and are contributing to the modularity of the system.
Abstract: In this paper, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies. The paper is primarily focused on high-power applications and specifically on high-voltage dc systems. The derived converter cells are treated as building blocks and are contributing to the modularity of the system. By combining the different building blocks, i.e., the converter cells, a variety of voltage and current source modular multilevel converter topologies are derived and thoroughly discussed. Furthermore, by applying the modularity principle at the system level, various types of high-power converters are introduced. The modularity of the multilevel converters is studied in depth, and the challenges as well as the opportunities for high-power applications are illustrated.
Citations
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01 Jan 1992
TL;DR: In this paper, a multilevel commutation cell is introduced for high-voltage power conversion, which can be applied to either choppers or voltage-source inverters and generalized to any number of switches.
Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>
1,202 citations
TL;DR: The development of MMC circuit topologies and their mathematical models over the years are presented and the evolution and technical challenges of the classical and model predictive control methods are discussed.
Abstract: Modular multilevel converter (MMC) is one of the most promising topologies for medium to high-voltage high-power applications. The main features of MMC are modularity, voltage and power scalability, fault tolerant and transformer-less operation, and high-quality output waveforms. Over the past few years, several research studies are conducted to address the technical challenges associated with the operation and control of the MMC. This paper presents the development of MMC circuit topologies and their mathematical models over the years. Also, the evolution and technical challenges of the classical and model predictive control methods are discussed. Finally, the MMC applications and their future trends are presented.
404 citations
Cites background from "Modular Multilevel Converters for H..."
...The output voltage of HB-SM consists of positive voltage levels (“0” and “vC1 ”) only and cannot support the bipolar operation and dc fault blocking [48]....
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TL;DR: In this article, two new modular multilevel converter (MMC) circuit configurations as well as a hybrid design methodology to embed the dc-fault-handling capability in the MMC-HVDC systems are proposed.
Abstract: The modular multilevel converter (MMC) has become the most promising converter technology for high-voltage direct current (HVDC) transmission systems. However, similar to any other voltage-sourced converter-based HVDC system, MMC-HVDC systems with the half-bridge submodules (SMs) lack the capability of handling dc-side short-circuit faults, which are of severe concern for overhead transmission lines. In this paper, two new SM circuit configurations as well as a hybrid design methodology to embed the dc-fault-handling capability in the MMC-HVDC systems are proposed. By combining the features of various SM configurations, the dc-fault current path through the freewheeling diodes is eliminated and the dc-fault current is enforced to zero. Several MMC configurations based on the proposed hybrid design method and various SM circuits, that is, the half-bridge, the full-bridge, the clamp-double, and the five-level cross-connected SMs, as well as the newly proposed unipolar-voltage full-bridge and three-level cross-connected SMs, are investigated and compared in terms of the dc-fault-handing capability, semiconductor power losses, and component requirements. The studies are carried out based on time-domain simulation in the PSCAD/EMTDC software environment for various SM configurations and dc-fault conditions. The reported study results demonstrate the proposed hybrid-designed MMC-HVDC system based on the combination of the half-bridge and the proposed SM circuits is the optimal design among all evaluated systems in terms of the dc-fault-handing capability, semiconductor power losses, and component requirements.
303 citations
Cites background from "Modular Multilevel Converters for H..."
...As of now, the MMC-HVDC systems have been realized mainly based on a single SM circuit configuration, that is, the half-bridge, the full-bridge, or the clamp-double SMs [4], [11], [15], [20]–[22]....
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...T HEMODULARmultilevel converter (MMC) has become themost attractive converter topology for voltage-sourced converter (VSC) high-voltage direct-current (HVDC) transmission systems because of its modularity and scalability [1]–[11]....
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TL;DR: Five main submodules (SMs) to be used as the basic structures of MLIs are presented and categorized and investigated with from different perspectives such as the number of components, the ability to create inherent negative voltage, working in regeneration mode and using single dc source.
Abstract: Multilevel inverters (MLIs) are being used in wide range of power electronic applications. These converters have attracted a lot of attention during recent years and exist in different topologies with similar basic concepts. This paper presents five main submodules (SMs) to be used as the basic structures of MLIs. The paper reviews the common MLI topologies from the structural point of view. The topologies are divided into the different SMs to show conventional MLI configurations and future topologies that can be created from the main SMs. A comparative study between different topologies is performed in detail. The MLIs are categorized and investigated with from different perspectives such as the number of components, the ability to create inherent negative voltage, working in regeneration mode and using single dc source.
298 citations
Cites background from "Modular Multilevel Converters for H..."
...high-voltage direct-current (HVdc) [3]–[6], especially with renewable energy extensions [7]–[12], power quality devices such as flexible ac transmission systems (FACTS) [13]–[16], static...
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References
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01 Jan 1980
TL;DR: In this article, a neutral-point-clamped PWM inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed.
Abstract: A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
4,432 citations
TL;DR: The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
Abstract: A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
4,328 citations
08 Oct 1995
TL;DR: This paper presents three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate DC sources.
Abstract: Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of DC capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate DC sources. The operating principle, features, constraints, and potential applications of these converters are discussed.
3,232 citations
TL;DR: In this article, the authors focus on the generation of electricity from clean and renewable sources, and show that wind energy has become the world's fastest growing energy source, and that renewable energy is the most promising energy source.
Abstract: As environmental concerns have focussed attention on the generation of electricity from clean and renewable sources, wind energy has become the world's fastest growing energy source. The authors dr ...
2,878 citations
23 Jun 2003
TL;DR: In this article, a new multilevel converter topology suitable for very high voltage applications, especially network interties in power generation and transmission, is presented, and a suitable structure of the converter-control is proposed.
Abstract: This paper presents a new multilevel converter topology suitable for very high voltage applications, especially network interties in power generation and transmission. The fundamental concept and the applied control scheme is introduced. Simulation results of a 36 MW-network intertie illustrate the efficient operating characteristics. A suitable structure of the converter-control is proposed.
2,806 citations
"Modular Multilevel Converters for H..." refers background in this paper
...This fundamental problem has been addressed in [82], opening a new field of possible new solutions....
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