A Review on Designand Control Methods of Modular Multilevel Converter

Author(s):  
Ramya G ◽  
Ramaprabha R

Modular multilevel converters (MMC) are an emerging voltage source converter topology suitable for many applications. Due to abundant utilization of HVDC power transmission, the modular multilevel converter has become popular converter type to be used in high voltage applications. Other applications include interfacing renewable energy power sources to the grid and motor drives. Modular multilevel converters are beneficial for high voltage and high power motor drives because of the properties of this converter topology, such as, low distortion, high efficiency, etc. For the past few years significant research has been carried out to address the technical challenges associated with operation and voltage balancing of MMC. In this paper, a detailed technical review on the control strategies is presented for ready reference.

Author(s):  
Araitz Iturregi ◽  
Agurtzane Etxegarai ◽  
D. Marene Larruskain ◽  
Pablo Eguia ◽  
Oihane Abarrategui

Goi-tentsioko korronte zuzeneko (ingelesez, High Voltage Direct Current HVDC) garraio-sistemak gero eta garrantzitsuagoak dira sistema elektrikoan, onura ekonomiko eta teknikoak direla eta. Hala ere, akatsen bat gertatzen denean, korrontea eteteak oraindik ere erronka izaten jarraitzen du HVDC sareetan. Desiragarriak ez diren korronteak eteteko, korronte zuzeneko etengailuak erabil daitezke, baina horien gaitasuna mugatua da. Egoera hala izanik, akats-korronteen mugagailuak (ingelesez, Fault Current Limiter FCL) dira proposamenik egokiena akats-korronteak maneiagarriagoak diren balioetara txikitzeko; hartara, sistema elektrikoaren garraio-ahalmena handitu daiteke, ekipamendua aldatu beharrik gabe. Sarean aldez aurretik legokeen ekipamendua gai izango litzateke korronte berriak kudeatzeko eta sistema era eraginkorrean babesteko FCLen erabilpenaz. Artikulu honetan, FCL tresnen ezaugarri orokorrak eta sailkapena aurkezten dira. Ondoren, egoera solidoko FCLa erabili da maila anizkoitzeko bihurgailudun (ingelesez, Modular Multilevel Converter MMC) VSC-HVDC (ingelesez, Voltage Source Converter) sistema batean, eta horren jokaera azaltzen da simulazio bidez.


2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Fei Chang ◽  
Zhongping Yang ◽  
Yi Wang ◽  
Fei Lin ◽  
Shihui Liu

The modular multilevel converter (MMC) is an emerging voltage source converter topology suitable for multiterminal high voltage direct current transmission based on modular multilevel converter (MMC-MTDC). This paper presents fault characteristics of MMC-MTDC including submodule fault, DC line fault, and fault ride-through of wind farm integration. Meanwhile, the corresponding protection strategies are proposed. The correctness and effectiveness of the control strategies are verified by establishing a three-terminal MMC-MTDC system under the PSCAD/EMTDC electromagnetic transient simulation environment.


Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5314
Author(s):  
Victor Ramon França Bezerra de Souza ◽  
Luciano Sales Barros ◽  
Flavio Bezerra Costa

New grid-connected systems have imposed additional requirements regarding reliability, power quality, high levels of power processing capacity, and fault support, where power converters have a crucial role in fulfilling these requirements. Overcoming one of these challenges, this paper proposes a new alternative application to improve the low-voltage ride-through (LVRT) support based on the arm impedance employment of the modular multilevel converter (MMC) by attenuating the fault impacts, avoiding overcurrents and overvoltages. This proposal does not require additional hardware or control loops for LVRT support, only using PI controllers. This paper evaluates symmetrical and asymmetrical grid fault impacts on the converter DC side of four converter topologies: two-level voltage source converter topology (2L-VSC), neutral point clamped (NPC), MMC, and 2L-VSC equipped with a DC-chopper, employing the same control structure for the four topologies, highlighting that the MMC contributed better to LVRT improvement under severe grid conditions.


2014 ◽  
Vol 538 ◽  
pp. 239-242
Author(s):  
Hao Wu ◽  
Ping Wang

Modular Multilevel has been widely applied in Flexible HVDC, electric locomotives and PET(Power Electronics Transformers). The modulation method is important for the converter performance. This paper presents an improved modulation method for Modular Multilevel Converter.


2021 ◽  
Vol 261 ◽  
pp. 01026
Author(s):  
Xinlin Zhang ◽  
Yanchi Zhang ◽  
Da Xie ◽  
Bowen Zhao

Modular multilevel converters are widely used in power systems because of their significant advantages. In this paper, a dynamic mathematical model is established by analyzing the topology, operating principle and switching function of the modular multilevel converter, so as to construct an inner and outer loop decoupling controller in dq coordinates. The carrier phase-shift pulse-width modulation is selected to control the sub-module operation, and the uncontrolled pre-charging method is adopted to charge the sub-module. Finally, simulation experiments are carried out in MATLAB/Simulink, and the results show that the control method achieves smooth start-up of the modular multilevel converter.


2018 ◽  
Vol 12 (1) ◽  
pp. 98-109 ◽  
Author(s):  
Adolfo Dannier ◽  
Gianluca Brando ◽  
Ivan Spina ◽  
Diego Iannuzzi

Objective:This paper analyses the Modular Multilevel Converter (MMC) topology, where each individual Sub Module (SM), in half bridge configuration, is directly fed by an elementary electrochemical cell.Methods:The aim is to investigate how the reference voltages influence the cells currents waveforms, determining how the active powers and the losses are distributed among the cells. Considering a 2-level Voltage Source Inverter (VSI) topology working in the same conditions, the ratio between the MMC total cells losses and VSI total cells losses is calculated. After showing the system architecture and mathematical model, the cells current waveform investigation is presented and detailed both for triangular and sinusoidal voltage reference waveform.Results:Finally, the results are critically discussed with particular focus on the comparison between the MMC and the VSI topologies.


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