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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 12 Aug 2020 23:04:04 GMT2020-08-12T23:04:04ZImpact of control algorithm solutions on Modular Multilevel Converters electrical waveforms and losses
http://hdl.handle.net/10985/13677
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
Modular Multilevel Converters (MMC) are becoming increasingly popular with the development of HVDC connection and, in the future, Multi Terminal DC grid. A lot of publications have been published about this topology these last years since it was first proposed. Many of them deal with converter control methods, other address the method of estimating losses. Usually, the proposed losses estimation techniques are associated to simple control methods For VSC (Voltage Sources Converters) topology, the losses minimization is based on the limitation of the RMS currents values. This hypothesis is usually extended to the control of MMC, by limiting the differential currents to their DC component, without really being checked. This paper investigates the impact of two control algorithms variants on electrical quantities (currents, capacitor voltages ripple, losses). From the published results, it is shown that in some cases the usual choice is not the best one.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/136772015-01-01T00:00:00ZGRUSON, FrançoisFREYTES, JulianSAMIMI, ShababDELARUE, PhilippeGUILLAUD, XavierCOLAS, FrédéricBELHAOUANE, Mohamed MoezModular Multilevel Converters (MMC) are becoming increasingly popular with the development of HVDC connection and, in the future, Multi Terminal DC grid. A lot of publications have been published about this topology these last years since it was first proposed. Many of them deal with converter control methods, other address the method of estimating losses. Usually, the proposed losses estimation techniques are associated to simple control methods For VSC (Voltage Sources Converters) topology, the losses minimization is based on the limitation of the RMS currents values. This hypothesis is usually extended to the control of MMC, by limiting the differential currents to their DC component, without really being checked. This paper investigates the impact of two control algorithms variants on electrical quantities (currents, capacitor voltages ripple, losses). From the published results, it is shown that in some cases the usual choice is not the best one.Improving Small-Signal Stability of an MMC With CCSC by Control of the Internally Stored Energy
http://hdl.handle.net/10985/12894
Improving Small-Signal Stability of an MMC With CCSC by Control of the Internally Stored Energy
FREYTES, Julian; BERGNA, Gilbert; JON ARE, SUUL; D'ARCO, Salvatore; GRUSON, François; COLAS, Frédéric; SAAD, Hani; GUILLAUD, Xavier
The DC-side dynamics of Modular Multilevel Converters (MMCs) can be prone to poorly damped oscillations or stability problems when the second harmonic components of the arm currents are mitigated by a Circulating Current Suppression Controller (CCSC). This paper demonstrates that the source of these oscillations is the uncontrolled interaction of the DC-side current and the internally stored energy of the MMC, as resulting from the CCSC. Stable operation and improved performance of the MMC control system can be ensured by introducing closed loop control of the energy and the DC-side current. The presented analysis relies on a detailed state-space model of the MMC which is formulated to obtain constant variables in steady state. The resulting state-space equations can be linearized to achieve a Linear Time Invariant (LTI) model, allowing for eigenvalue analysis of the small-signal dynamics of the MMC. Participation factor analysis is utilized to identify the source of the poorly damped DC-side oscillations, and indicates the suitability of introducing control of the internal capacitor voltage or the corresponding stored energy. An MMC connected to a DC power source with an equivalent capacitance, and operated with DC voltage droop in the active power flow control, is used as an example for the presented analysis. The developed small-signal models and the improvement in small-signal dynamics achieved by introducing control of the internally stored energy are verified by time-domain simulations in comparison to an EMT simulation model of an MMC with 400 sub-modules per arm.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/128942018-01-01T00:00:00ZFREYTES, JulianBERGNA, GilbertJON ARE, SUULD'ARCO, SalvatoreGRUSON, FrançoisCOLAS, FrédéricSAAD, HaniGUILLAUD, XavierThe DC-side dynamics of Modular Multilevel Converters (MMCs) can be prone to poorly damped oscillations or stability problems when the second harmonic components of the arm currents are mitigated by a Circulating Current Suppression Controller (CCSC). This paper demonstrates that the source of these oscillations is the uncontrolled interaction of the DC-side current and the internally stored energy of the MMC, as resulting from the CCSC. Stable operation and improved performance of the MMC control system can be ensured by introducing closed loop control of the energy and the DC-side current. The presented analysis relies on a detailed state-space model of the MMC which is formulated to obtain constant variables in steady state. The resulting state-space equations can be linearized to achieve a Linear Time Invariant (LTI) model, allowing for eigenvalue analysis of the small-signal dynamics of the MMC. Participation factor analysis is utilized to identify the source of the poorly damped DC-side oscillations, and indicates the suitability of introducing control of the internal capacitor voltage or the corresponding stored energy. An MMC connected to a DC power source with an equivalent capacitance, and operated with DC voltage droop in the active power flow control, is used as an example for the presented analysis. The developed small-signal models and the improvement in small-signal dynamics achieved by introducing control of the internally stored energy are verified by time-domain simulations in comparison to an EMT simulation model of an MMC with 400 sub-modules per arm.Losses estimation method by simulation for the Modular Multilevel Converter
http://hdl.handle.net/10985/13255
Losses estimation method by simulation for the Modular Multilevel Converter
FREYTES, Julian; GRUSON, François; DELARUE, Philippe; COLAS, Frédéric; GUILLAUD, Xavier
The modular multilevel converter (MMC) is the most promising solution to connect HVDC grids to a HVAC one. The installation of new equipment in the HVDC transmission systems requires an economic study where the power losses play an important role. Since the MMC it is composed of a high number of semiconductors components, the losses estimation becomes complex. This paper proposes a simulation based method for the losses estimation that combines the MMC averaged and instantaneous model in a modular way. The method brings the possibility to perform comparisons in terms of losses for different modules technologies as well as different high and low level control techniques. Also the losses characteristics within the MMC are also discussed and the passive losses are firstly taken into account
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/132552015-01-01T00:00:00ZFREYTES, JulianGRUSON, FrançoisDELARUE, PhilippeCOLAS, FrédéricGUILLAUD, XavierThe modular multilevel converter (MMC) is the most promising solution to connect HVDC grids to a HVAC one. The installation of new equipment in the HVDC transmission systems requires an economic study where the power losses play an important role. Since the MMC it is composed of a high number of semiconductors components, the losses estimation becomes complex. This paper proposes a simulation based method for the losses estimation that combines the MMC averaged and instantaneous model in a modular way. The method brings the possibility to perform comparisons in terms of losses for different modules technologies as well as different high and low level control techniques. Also the losses characteristics within the MMC are also discussed and the passive losses are firstly taken into accountDynamic Analysis of MMC-Based MTDC Grids : Use of MMC Energy to Improve Voltage Behavior
http://hdl.handle.net/10985/14517
Dynamic Analysis of MMC-Based MTDC Grids : Use of MMC Energy to Improve Voltage Behavior
FREYTES, Julian; AKKARI, Samy; RAULT, Pierre; BELHAOUANE, Mohamed Moez; GRUSON, François; COLAS, Frédéric; GUILLAUD, Xavier
This article deals with DC voltage dynamics of Multi-Terminal HVDC grids (MTDC) with energy-based controlled Modular Multilevel Converters (MMC) adopting the commonly used power-voltage droop control technique for power flow dispatch. Special focus is given on the energy management strategies of the MMCs and their ability to influence on the DC voltage dynamics. First, it is shown that decoupling the MMC energy from the DC side, causes large and undesired DC voltage transient after a sudden power flow change. This occurs when this energy is controlled to a fixed value regardless of the DC voltage level. Second, the Virtual Capacitor Control technique is implemented in order to improve the results. However, its limitations on droop-based MTDC grids are highlighted. Finally, a novel energy management approach is proposed to improve the performance of the later method. These studies are performed with detailed MMC models suitable for the use of linear analysis techniques. The derived MTDC models are validated against time-domain simulations using detailed EMT MMC models with 400 sub-modules per arm.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/145172019-01-01T00:00:00ZFREYTES, JulianAKKARI, SamyRAULT, PierreBELHAOUANE, Mohamed MoezGRUSON, FrançoisCOLAS, FrédéricGUILLAUD, XavierThis article deals with DC voltage dynamics of Multi-Terminal HVDC grids (MTDC) with energy-based controlled Modular Multilevel Converters (MMC) adopting the commonly used power-voltage droop control technique for power flow dispatch. Special focus is given on the energy management strategies of the MMCs and their ability to influence on the DC voltage dynamics. First, it is shown that decoupling the MMC energy from the DC side, causes large and undesired DC voltage transient after a sudden power flow change. This occurs when this energy is controlled to a fixed value regardless of the DC voltage level. Second, the Virtual Capacitor Control technique is implemented in order to improve the results. However, its limitations on droop-based MTDC grids are highlighted. Finally, a novel energy management approach is proposed to improve the performance of the later method. These studies are performed with detailed MMC models suitable for the use of linear analysis techniques. The derived MTDC models are validated against time-domain simulations using detailed EMT MMC models with 400 sub-modules per arm.