Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses

Gruson, François; Freytes, Julian; Samimi, Shabab; Delarue, Philippe; Guillaud, Xavier; Colas, Frédéric; Belhaouane, Mohamed Moez

doi:10.1109/epe.2015.7309115

Cited by 10 publications

(10 citation statements)

References 10 publications

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“…Usually, one suggests that it is necessary to limit the RMS value of the currents flowing through the converters to limit their losses. However, reference [26] shows that the conduction losses of the MMC are not only related to the currents' RMS values, but also the waveforms of these currents and therefore the MMC control algorithms. Because the total losses in the MMC are very low (around 1% of the nominal power), the estimation of MMC losses is not studied in this paper.…”

Section: ) Hvdc Cables and Onshore MMC Lossesmentioning

confidence: 99%

Overvoltage Limitation Method of an Offshore Wind Farm With DC Series-Parallel Collection Grid

Zhang

Gruson

et al. 2019

IEEE Trans. Sustain. Energy

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This paper describes the characteristics of a series parallel wind farm (SPWF) topology and investigates the control strategy to ensure its safe operation. The SPWF was found to have advantages over other pure dc wind farm architectures in terms of lower construction cost and lower power losses in the collection system. However, unbalance power productions among the wind turbines cause the variations of their output voltages, which may endanger the safe operation of the entire wind farm. This paper proposes a global control strategy that prevents wind turbines from operating above their overvoltage capabilities. With an active participation of the onshore converter, the proposed strategy allows maximum power point tracking (MPPT) of the wind turbines. The practical limitations of this strategy are discussed and improvements are given. The feasibility of the proposed method is validated in a simulation of 300 MW wind farm developed in EMTP-RV.

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Section: ) Hvdc Cables and Onshore MMC Lossesmentioning

confidence: 99%

Overvoltage Limitation Method of an Offshore Wind Farm With DC Series-Parallel Collection Grid

Zhang

Gruson

et al. 2019

IEEE Trans. Sustain. Energy

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“…The chosen rated active power is equal to 5 kW and its rated reactive power to 1.5 kVAR. As presented in [4] and [5], the sum of all the voltages of each SM in an arm is usually close to the DC bus voltage of the converter, 400V for this application. This voltage has to be split equitably on all the SM in the same arm so the nominal chosen voltage of the SM capacitor (V cj ) is equal to 20V.…”

Section: Design Of the Power Part Of The Convertermentioning

confidence: 99%

“…In high power application, the MMC converter has a large number of SM, the generated voltages have a really good quality (401 levels for the real device), and the inductances are not sized to limit the ripple currents contrary to the classical 2 level VSC but to limit the gradient of the DC and AC currents of the converter in case of a failure of the DC or the AC grid. This sizing is given by equations (3) and (4) respectively for the arm and grid side inductances. Derivative terms are equals to 6.4MA per seconds in the full scale converter [5].…”

Section: Inductances L and L Arm Sizingmentioning

confidence: 99%

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Design, implementation and testing of a Modular Multilevel Converter

et al. 2017

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The Modular Multilevel Converter (MMC) is a power electronic structure used for high voltage adjustable speed drives applications as well as power transmission applications and high-voltage direct current (HVDC). MMC structure presents many advantages such as modularity, the absence of a high voltage DC bus and very low switching frequency. It presents also some disadvantages such as modeling complexity and control due to the large number of semiconductors to control. The objectives of this paper are to present the methodology to design a laboratory MMC converter and its control system. This methodology is based on an intensive used of real-time simulation, to develop and test the control algorithm is proposed. This MMC prototype must be as realistic as possible to a full scale MMC, with a large number of SM (i.e. 640kV on the DC side, a rated power of 1GW and 400 sub-modules). A control hardware integrating distributed processors (one for each arm) and a master control is presented. The protocols to validate sub-modules, arms and the converter are explained.

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“…3 It has attracted a lot of interest due to its excellent output voltage quality waveforms with good performance and high efficiencies for HVDC applications. [4][5][6] The MMC consists of more than 400 identical series-connected submodules (SMs) per arm. 7 As illustrated there, the controllable semiconductor device may be an insulated-gate bipolar transistor (IGBT).…”

Section: Introductionmentioning

confidence: 99%

Global advanced control strategy for Modular Multilevel Converter integrated in a HVDC link

Ayari

Belhaouane

Guillaud

et al. 2018

Int Trans Electr Energ Syst

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Modular Multilevel Converter (MMC) is becoming a promising converter technology for high-voltage direct current transmission systems due to its high modularity, availability, and power quality. It is a multi-input-multi-output nonlinear system. The control system for MMC is required to simultaneously achieve multiple control objectives. Existing control strategies for MMC are complex and the controller parameter design is not straightforward for the nonlinear systems with highly coupled states. In view of this, a steady-state model for the MMC is developed on bilinear deviation state-space model around a working point. Based on linear quadratic regulator and least squares methods, a nonlinear polynomial feedback law is designed to simultaneously control the grid and differential currents, and the global stored energy and energy balancing between total upper and lower arms. To generate the optimal current references, a multivariable linear quadratic controller is used to regulate the total energy per leg, energy difference between each upper and lower arms, and the DC bus voltage. The proposed high-level controller depicts an original advanced control structure of MMC converter. The performance of the proposed strategy for a detailed model of 400-level MMC is evaluated using simulations in MATLAB/SIMULINK/SPS software environment. KEYWORDSbilinear model, LQR approach, Modular Multilevel Converter (MMC), energies and DC voltage control, polynomial control Int Trans Electr Energ Syst. 2018;28:e2511. wileyonlinelibrary.com/journal/etep

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Impact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses

Abstract: Study the impact of two control variants (compensation of the average or the instantaneous AC grid power) : differential and AC grid currents, capacitor voltages ripple, losses.

Cited by 10 publications

References 10 publications

Overvoltage Limitation Method of an Offshore Wind Farm With DC Series-Parallel Collection Grid

Overvoltage Limitation Method of an Offshore Wind Farm With DC Series-Parallel Collection Grid

Design, implementation and testing of a Modular Multilevel Converter

Global advanced control strategy for Modular Multilevel Converter integrated in a HVDC link

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