Nonlinear control for modular multilevel converters with enhanced stability region and arbitrary closed loop dynamics

Oliveira, Guacira Costa de; Damm, Gilney; Monaro, Renato M.; Lourenço, Luís F. Normandia; Carrizosa, Miguel Jiménez; Lamnabhi‐Lagarrigue, Françoise

doi:10.1016/j.ijepes.2020.106590

Cited by 10 publications

(11 citation statements)

References 16 publications

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“…Given the chosen model, one can design a control system for the MMC-HVDC. The control problem associated with the MMC is more complex than the one associated with two-or three-level VSCs [48,53]. The complexity arises from the growth in the number of variables to be controlled compared to the two-and three-level VSCs resulting from the converter circulating current and the internal energy stored in the submodules of the capacitors.…”

Section: Modular Multilevel Converter Modelmentioning

confidence: 99%

“…When using the bilinear model for the internal dynamics, the reference of the d component of the circulating current can be used to regulate the energy balance ∆W between the upper and lower arms. Moreover, the reference of the 0 component is used to regulate the internal energy W of the converter (see [52,53] for more details on the MMC control using a bilinear dq0 model). These reference calculations were carried out by the energy balance control and the energy control, respectively.…”

Section: Grid Following (Gfl)mentioning

confidence: 99%

“…These reference calculations were carried out by the energy balance control and the energy control, respectively. The reference for the q component was chosen as zero to diminish power losses, in this case, without loss of generality [53].…”

Section: Grid Following (Gfl)mentioning

confidence: 99%

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Stability Analysis of Grid-Forming MMC-HVDC Transmission Connected to Legacy Power Systems

et al. 2021

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The power system is going through a change in its very foundations. More and more power converters are being integrated into the electric grid to interface renewable energy resources and in high-voltage direct-current (HVDC) transmission systems. This article presents a discussion on the stability of power systems when HVDC transmission systems based on modular multilevel converters (MMC) are connected in grid-forming (GFM) mode to the legacy power system using concepts of energy functions and Lyapunov stability theory and considering aspects of the interoperability between GFM converter technologies. As a base for the stability analysis, we review the main GFM converter technologies (droop and virtual synchronous machine), highlighting their differences. Then, we present a model using the center-of-inertia formulation for a multi-machine/multi-GFM converter power system representing a close future scenario of power systems where GFM converters might adopt different technologies. To illustrate the theoretical Lyapunov-based stability analysis, simulations performed in Matlab/Simulink showed the behavior of a 12-bus test system during a frequency disturbance that originated from the sudden connection of a load. To reflect the interoperability of different GFM technologies and the power system, scenarios with one single GFM technology and a scenario with mixed technologies were investigated. For the test system considered, the frequency response with fewer oscillations and a higher frequency nadir was obtained when all GFM converters were operated as VSMs that have a higher inertial response contribution.

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Section: Modular Multilevel Converter Modelmentioning

confidence: 99%

Section: Grid Following (Gfl)mentioning

confidence: 99%

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Stability Analysis of Grid-Forming MMC-HVDC Transmission Connected to Legacy Power Systems

et al. 2021

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“…However, the arm current decides the minimum (iarm≤0) and maximum (iarm≥0) number of voltage to be inserted for balancing the capacitor voltage in each SM. Many different voltage sorting algorithm have been proposed based on the selection of number of SM to be inserted for balancing the capacitor [17,20]. Though they have unique advantages compared to the conventional method, it causes more complexity when the number of SM are increased.…”

Section: B Proposed Evs Algorithmmentioning

confidence: 99%

“…However, this technique causes an uneven balancing when subjected to high switching frequency and thus eventually increases the capacitor ripple voltage. The closed loop feedback control approach [20][21] used to balance the capacitor voltage using feedback controller and the obtained signal is once again adjusted using phase shifted modulating signals. Based on phase shifting, the capacitor voltage is balanced properly but it causes more complexity in control function.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Voltage Sorting Algorithm for Balancing the Capacitor Voltage in Modular Multilevel Converter

Ismail

Kaliyaperumal²

2021

IEEE Access

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In this paper, an enhanced voltage sorting algorithm is proposed for balancing each sub module capacitor voltage in modular multilevel converter (MMC). However, the submodule (SM) voltage strategy becomes more complex when it increases to a number of levels, which eventually increases voltage ripples and circulating current. In order to overcome this problem, an enhanced voltage sorting algorithm is proposed, which implies an enhanced control logic function for capacitor voltage balancing of the converter. The switching pattern of each SM floating capacitor is determined based on the modulating signal methodology, which is then compared with the hybrid state condition using arm current direction in the MMC. Additionally, the generated hybrid signals are once again compared with the dynamic implicit number by conjoining the switching logic state variables. Due to this comparison of logic function, the capacitor voltage is balanced properly and reduces the capacitor ripple voltage to a permissible limit compared to the conventional method. Hence, compared to other balancing techniques, the circulating current is reduced by using conventional control techniques. The desired pulse signals for the power devices are obtained based on the multi carrier pulse width modulation techniques. The superior performance of the proposed algorithm is tested using MATLAB/Simulink software and real time laboratory hardware setup for different load conditions. Apart from this, the effective performance of the proposed method has been validated in the HVDC transmission system.

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New backstepping controllers with enhanced stability for neutral point clamped converters interfacing photovoltaics and AC microgrids

Barros

Silva

Rocha

2023

International Journal of Electrical Power & Energy Systems

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Nonlinear control for modular multilevel converters with enhanced stability region and arbitrary closed loop dynamics

Cited by 10 publications

References 16 publications

Stability Analysis of Grid-Forming MMC-HVDC Transmission Connected to Legacy Power Systems

Stability Analysis of Grid-Forming MMC-HVDC Transmission Connected to Legacy Power Systems

Enhanced Voltage Sorting Algorithm for Balancing the Capacitor Voltage in Modular Multilevel Converter

New backstepping controllers with enhanced stability for neutral point clamped converters interfacing photovoltaics and AC microgrids

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