| 1. |
- Ciftci, Baris, et al.
(författare)
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Wireless control of modular multilevel converter autonomous submodules : 23rd European Conference on Power Electronics and Applications
- 2021
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Ingår i: Proceedings 23rd European Conference on Power Electronics and Applications. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- The wireless control of modular multilevel converter (MMC) submodules might offer advantages for MMCs with a high number of submodules. However, the control system should tolerate the stochastic nature of the wireless communication, continue the operation flawlessly or, at least, avoid overcurrents, overvoltages, and component failures. The previously proposed control methods enabled to control the submodules wirelessly with consecutive communication errors up to hundreds of control cycles. The submodule control method in this paper facilitates the MMC to safely overcome communication errors that last longer and when the MMC experiences significant electrical disturbances during the errors. The submodules are proposed to operate autonomously by implementing a replica of the central controller in the submodules and drive the replicas based on the local variables and the previously received data. The simulation and experimental results verify the proposed control method.
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| 2. |
- Ciftci, Baris, et al.
(författare)
-
Wireless control of modular multilevel converter submodules under ac-side faults
- 2021
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Konferensbidrag (refereegranskat)abstract
- Wireless control of modular multilevel converter (MMC) submodules has been offered recently with potentially lower cost and higher availability advantages for the converter station. In this paper, the wireless control of MMC submodules under ac-side faults is investigated. The central controller of the MMC is equipped for the unbalanced grid conditions. Local current controllers in the submodules are operated autonomously in case of loss of wireless communication during the fault. A set of simulations with single line-to-ground, line-to-line, and three-phase-to-ground faults reveal that the MMC rides through the faults in all the cases with the expected communication conditions or when the communication is lost before or after the fault instant.
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| 3. |
- Liao, Yicheng, et al.
(författare)
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Controller design-oriented analysis of grid-forming converters for stability robustness enhancement
- 2021
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Ingår i: Chinese Journal of Electrical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 2096-1529. ; 7:4, s. 37-48
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Tidskriftsartikel (refereegranskat)abstract
- Grid-forming converters can suffer from control interaction problems in grid connections that can result in small-signal instability. Their inner-loop voltage controller tends to interact with the outer-loop power controller, rendering the controller design more difficult. To conduct a design-oriented analysis, a control-loop decomposition approach for grid-forming converters is proposed. Combined with impedance-based stability analysis, the control-loop decomposition approach can reveal how different control loops affect the converter-grid interaction. This results in a robust controller design enabling grid-forming converters to operate within a wider range of grid short-circuit ratios. Finally, simulation and experimental results, which validate the approach, are presented.
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| 4. |
- Liao, Yicheng, et al.
(författare)
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Small-Signal Modeling of AC Power Electronic Systems : Critical Review and Unified Modeling
- 2021
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Ingår i: IEEE OPEN JOURNAL OF POWER ELECTRONICS. - : Institute of Electrical and Electronics Engineers (IEEE). - 2644-1314. ; 2, s. 424-439
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Forskningsöversikt (refereegranskat)abstract
- The harmonic state-space (HSS), the dynamic phasor (DP), and the generalized dq (GDQ) modeling are three widely used methods for small-signal analysis of ac power electronic systems. By reviewing their principles and deriving their mathematical relationships, this paper proposes a unified framework for all the three approaches. The unified modeling reveals that the linearization and transformation can be exchanged flexibly in the modeling process, and the initial phase takes a role in transforming the GDQ model into the HSS or DP model. Case studies on a three-phase voltage-source converter in unbalanced power grids are provided for validation. The relationships of three modeling methods are verified by mathematical proofs and time-domain simulations. The unified frequency-domain model is further validated through the frequency scan in experiments. Insights of the unified modeling framework and recommendations from engineering perspectives are finally discussed.
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| 5. |
- Wu, Heng, et al.
(författare)
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Development of an AC/DC Impedance Matrix Measurement Toolbox for MTDC System
- 2021
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Ingår i: Proceedings 20th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants, WIW 2021. - : Institution of Engineering and Technology (IET). ; , s. 442-448
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Impedance-based stability analysis has the potential to be adopted by transmission system operators (TSOs) for effectively assessing the stability of multi-terminal HVDC (MTDC) system. This paper introduces a PSCADcompatible software toolbox that enables the accurate frequency dependent AC/DC impedance (matrix) measurement of the MMC-HVDC converter stations. Case studies based on a generic MTDC model are given to demonstrate the effectiveness of using the toolbox for accurate impedance measurement as well as stability assessment.
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| 6. |
- Zhang, Hongyang, et al.
(författare)
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Loop-at-a-Time Stability Analysis for Grid-Connected Voltage-Source Converters
- 2021
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 9:5, s. 5807-5821
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Tidskriftsartikel (refereegranskat)abstract
- The instability phenomena caused by converter–grid interactions can be prevented by designing controllers with adequate stability margins. Yet, the multiple-input–multiple-output (MIMO) dynamics of grid-connected voltage-source converters (VSCs) complicate the stability analysis for the controller design. To tackle this challenge, this article presents a loop-at-a-time stability analysis for grid-connected VSCs, which not only shows close correlations with the generalized Nyquist criterion for MIMO systems but also enables to quantify the stability margins of individual closed loops. Moreover, the interactions between the closed loops can be analyzed. Test cases with numerical sensitivity analysis, simulations, and field measurements of a converter validate the theory.
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| 7. |
- Zhang, Mengfan, et al.
(författare)
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Data-Driven Modeling of Power-Electronics-Based Power System Considering the Operating Point Variation
- 2021
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Ingår i: 2021 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 3513-3517
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Konferensbidrag (refereegranskat)abstract
- Large-scale integrations of power-electronics devices have introduced the stability challenges to the conventional power system. The stability of the power-electronics-based power systems, which are modeled by a Multi-Input Multi-Output (MIMO) transfer function matrix, can be analyzed based on the Nyquist Criterion. However, since no or limited information about the internal control details, this matrix can only be obtained using the measured data. On the other hand, the elements of the matrix will change along with the operating point of each power-electronics converter, which introduces the challenge to guarantee the interaction stability of each inverter at different operating points. In this paper, a data-driven method is proposed to overcome this operating-point dependent challenge. An artificial neural network (ANN) is used to characterize the operating-point dependent model of power-electronics-based power systems. The comparison results confirm the accuracy of the impedance model obtained by this data-driven modeling method.
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