kth.sePublikationer
Ändra sökning
Avgränsa sökresultatet
12 1 - 50 av 69
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Bhadoria, Shubhangi
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Dijkhuizen, Frans
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Hitachi Energy Res, SE-72178 Västerås, Sweden..
    Raj, Rishabh
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Xu, Qianwen
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Matioli, Elison
    Ecole Polytech Fed Lausanne EPFL, Inst Elect Engn, CH-1015 Lausanne, Switzerland..
    Kostov, Konstantin
    Res Inst Sweden, S-16440 Stockholm, Sweden..
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Enablers for Overcurrent Capability of Silicon-Carbide-Based Power Converters: An Overview2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 3, s. 3569-3589Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the increase in penetration of power electronic converters in the power systems, a demand for overcurrent/ overloading capability has risen for the fault clearance duration. This article gives an overview of the limiting factors and the recent technologies for the overcurrent performance of SiC power modules in power electronics converters. It presents the limitations produced at the power module level by packaging materials, which include semiconductor chips, substrates, metallization, bonding techniques, die attach, and encapsulation materials. Specifically, technologies for overcurrent related temperatures in excess of 200 degrees C are discussed. This article also discusses potential technologies, which have been proven or may be potential candidates for improving the safe operating area. The discussed technologies are use of phase-change materials below the semiconductor chip, Peltier elements, new layouts of the power modules, control and modulation techniques for converters. Special attention has been given to an overview of various potential phase-change materials, which can be considered for high-temperature operations.

  • 2.
    Chen, Feifan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Zhao, Liang
    Aalborg University, Dept. of Energy Technology, Aalborg, Denmark.
    Harnefors, Lennart
    ABB Corporate Research, Västerås, Sweden.
    Kukkola, Jarno
    ABB Oy Drives, Helsinki, Finland.
    Routimo, Mikko
    ABB Oy Drives, Helsinki, Finland.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Dynamics Enhancement for Power Synchronization Control with Asymmetric AC Voltage Controller in Strong Grids2023Ingår i: 2023 IEEE Conference on Control Technology and Applications, CCTA 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 1066-1070Konferensbidrag (Refereegranskat)
    Abstract [en]

    Power synchronization control (PSC) is designed for weak grid connections originally and its performance is weakened when connected to a strong grid. In this paper, an asymmetric AC voltage controller (AVC) is proposed to improve the performance of PSC in strong grids. The improvement is achieved by adding a coupling from d-axis to q-axis to the voltage control part. The effect of this d-to-q coupling is explained by small signal modeling. It is found that the asymmetric AVC gives an effective improvement in damping the low-frequency oscillation and stability robustness against the grid strengths. Theoretical analysis and experiments verify the effectiveness of the proposed asymmetric AVC.

  • 3.
    Chen, Feifan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik.
    Zhao, Liang
    Aalborg University, Department of Energy Technology, Aalborg, Denmark.
    Harnefors, Lennart
    ABB Corporate Research, ABB, Västerås, Sweden.
    Kukkola, Jarno
    Oy Drives ABB, Helsinki, Finland.
    Routimo, Mikko
    Oy Drives ABB, Helsinki, Finland.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Pitfalls of Using Passivity Index to Guide Grid-connected Inverter Control Design in Low-frequency Region2023Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 758-764Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main purpose of this article is to elaborate on the pitfalls of using the frequency-domain passivity theories in grid-inverter interactions within the low-frequency range. It mainly covers the relationship between the passivity index and stability, considerations for control design guided by optimizing the passivity index, and issues with a negative infinite index. It is advised to exercise caution when applying passivity theory in the low-frequency range. These conclusions have been substantiated through numerical and experimental studies.

  • 4.
    Chen, Feifan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Zhao, Liang
    Aalborg Univ, Dept Energy Technol, Aalborg, Denmark..
    Harnefors, Lennart
    ABB, Corp Res, Västerås, Sweden..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Impedance Modeling for Quadrature-Axis Active Damping of PLL Dynamics2022Ingår i: 2022 IEEE 23RD WORKSHOP ON CONTROL AND MODELING FOR POWER ELECTRONICS (COMPEL 2022), IEEE , 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    When grid-following voltage source converters (VSCs) operate in inverter mode, the phase-locked loop (PLL) dynamics introduce a negative-real-part impedance, which may lead to the instability of the closed-loop system, especially in a weak-grid connection. This undesirable property of the PLL may be offset by so-called active damping. Nevertheless, the interaction between the active damping and the adverse PLL impact is not fully understood. To this end, the properties of different active-damping methods are analyzed, with the focus on the q-to-q coupling of the input admittance. One important finding is that adding an integrator to the q-axis active damper can improve the system performance in a weak-grid connection. Simulations and experimental results verify the theoretical analysis.

  • 5.
    Chen, Feifan
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Zhao, Liang
    Aalborg Univ, Dept Energy Technol, DK-9220 Aalborg, Denmark..
    Harnefors, Lennart
    ABB Corp Res, S-72226 Västerås, Sweden..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Kukkola, Jarno
    ABB Oy Drives, Helsinki 00380, Finland..
    Routimo, Mikko
    ABB Oy Drives, Helsinki 00380, Finland..
    Enhanced Q-Axis Voltage-Integral Damping Control for Fast PLL-Synchronized Inverters in Weak Grids2024Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 39, nr 1, s. 424-435Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase-locked loop (PLL) is a commonly used synchronization control method for grid-tied inverters. The PLL-synchronized inverters tend to have poor stability robustness with weak grid interconnections, especially when the PLL is designed with a high control bandwidth. To tackle this challenge, this article proposes an enhanced q-axis voltage-integral damping control, which not only stabilizes PLL-synchronized inverters in weak grids but also lifts the restriction on PLL bandwidth. This superior feature enables inverters to operate stably in ultraweak grids and with a superior transient response. The experimental tests confirm the performance of the method with 400-Hz PLL bandwidth under a short-circuit ratio of 1.28 of the grids.

  • 6.
    Chen, Yaow Ming
    et al.
    National Taiwan University, Taipei, Taiwan.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Editorial 2024: Cheers to a New Year of Power Electronics Excellence2024Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 39, nr 1, s. 4-5Artikel i tidskrift (Refereegranskat)
  • 7.
    Cheng, Li
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Yang, Huoming
    Technische Universität Berlin, Department of Power Electronics, Berlin, Germany.
    Nordström, Lars
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Design of Neural Network for Adaptive Current Control with Different Short-Circuit Ratios2022Ingår i: Proceedings IECON 2022 - 48th Annual Conference of the IEEE Industrial Electronics Society, Institute of Electrical and Electronics Engineers (IEEE) , 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current control of grid-connected converters may result in harmonic instability when grid impedance changes. To prevent this issue, current controller parameters can be tuned adaptively according to different short-circuit ratios (SCRs). It is thus important to estimate the grid impedance in real-time. Unlike traditional FFT-based impedance measurement methods, a more efficient estimation approach based on neural networks is proposed in this paper. This method does not require a fixed and relatively long sampling window, making it possible for real-time impedance measurement. Further, a step-by-step design method of the feedforward neural network (FNN) used for grid impedance estimation is developed. Time-domain simulation results validate the effectiveness of the approach. Based on the designed FNN, adaptive current control is implemented and verified through simulation.

  • 8.
    Cheng, Li
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wu, Yang
    Aalborg University, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Chen, Minjie
    Princeton University, Princeton, New Jersey, U.S.A..
    Li, Yufei
    Princeton University, Princeton, New Jersey, U.S.A..
    Nordström, Lars
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Dijkhuizen, Frans
    Hitachi Energy Research, Västerås, Sweden.
    Online Identification of Wind Farm Wide Frequency Admittance with Power Cables Using the Artificial Neural Network2023Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 1530-1535Konferensbidrag (Refereegranskat)
    Abstract [en]

    In power-electronic-based power systems like wind farms, stability analysis requires knowledge of system impedance across a wide frequency range, from sub-harmonic frequencies to the Nyquist frequency. Although it is feasible to take the fundamental frequency measurement during power system operation, obtaining a wide-frequency impedance curve in real time is very challenging. This paper proposed an ANN-based approach to estimate wide-frequency system admittance of wind farms with power cables, through fundamental frequency measurements. Real-life uncertainties are considered, including shunt capacitor injection, filter inductance variance, cable aging, errors in voltage and current measurements, and the variance of other system parameters. The generalization ability of the ANN is validated on a new dataset with different uncertainty distributions, and the error sensitivity to the potential system parameter variance is evaluated. These results can be referenced in the data acquisition step in future neural-network-based applications.

  • 9.
    Cheng, Li
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wu, Yang
    Aalborg University, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Chen, Minjie
    Princeton University, Princeton, New Jersey, U.S.A.
    Zhou, Zichao
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nordström, Lars
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Neural-Network-Based Impedance Estimation for Transmission Cables Considering Aging Effect2023Ingår i: 2023 8th IEEE Workshop on the Electronic Grid, eGRID 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Konferensbidrag (Refereegranskat)
    Abstract [en]

    In power-electronic-based power systems like wind farms, conducting stability analysis necessitates a comprehensive understanding of the system impedance across a wide frequency range, from sub-harmonic frequencies up to the Nyquist frequency of control systems of power converters. The cable aging effect can significantly impact the cable impedance, while accurately estimating the degree of aging proves challenging. To avoid the requirement for precise aging prognostic, this paper proposes an approach based on Artificial Neural Networks (ANN) that enables the estimation of AC cable impedance in a wind farm solely through fundamental frequency measurements. The data used for training the ANN is obtained from the cable model in PSCAD, incorporating physical and geometrical parameters, which accurately approximates real cables within power systems. The training results of the ANN validate the accuracy of the proposed identification approach. As a result, the proposed approach effectively eliminates the potential misjudgment of system stability caused by the aging effect of power cables.

  • 10.
    Ciftci, Baris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Augustin, Tim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Norrga, Staffan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wireless Communication in Modular Multilevel Converters and Electromagnetic Interference CharacterizationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The wireless control of modular multilevel converter (MMC) submodules was recently proposed. The success of the control depends on specialized control methods suitable for wireless communication and a properly designed wireless communication network in the MMC valve hall while aiming for low latency and high reliability. The wireless communication in the hall can be affected by the electromagnetic interference (EMI) of MMC submodules, voltage and current transients. In this article, firstly, a wireless communication network based on 5G New Radio is designed for an example full-scale MMC valve hall. After that, radiated EMI characteristics of MMC submodules with different voltage and current ratings and two dc circuit breakers are measured. The effects of EMI on wireless communication in the multi-GHz frequency band are tested. The interference from the components is confined below 500 MHz, and the wireless communication with 5825 MHz center frequency is not affected by the interference.

  • 11.
    Ciftci, Baris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Augustin, Tim
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Norrga, Staffan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wireless Communication in Modular Multilevel Converters and Electromagnetic Interference Characterization2022Ingår i: IEEE Access, E-ISSN 2169-3536, s. 38189-38201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wireless control of modular multilevel converter (MMC) submodules was recently proposed. The success of the control depends on specialized control methods suitable for wireless communication and a properly designed wireless communication network in the MMC valve hall while aiming for low latency and high reliability. The wireless communication in the hall can be affected by the electromagnetic interference (EMI) of MMC submodules, voltage and current transients. In this article, firstly, a wireless communication network based on 5G New Radio is designed for an example full-scale MMC valve hall. After that, the radiated EMI characteristics of the MMC submodules with different voltage and current ratings and two dc circuit breakers are measured. The effects of EMI on wireless communication in the multi-GHz frequency band are tested. The interference from the components is confined below 500 MHz, and the wireless communication with 5825 MHz center frequency is not affected by the interference.

    Ladda ner fulltext (pdf)
    fulltext
  • 12.
    Ciftci, Baris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Norrga, Staffan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wireless control of modular multilevel converter autonomous submodules: 23rd European Conference on Power Electronics and Applications2021Ingår i: Proceedings 23rd European Conference on Power Electronics and Applications, Institute of Electrical and Electronics Engineers (IEEE), 2021, , s. 10Konferensbidrag (Refereegranskat)
    Abstract [en]

    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 13.
    Ciftci, Baris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Norrga, Staffan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wireless control of modular multilevel converter submodules under ac-side faults2021Konferensbidrag (Refereegranskat)
    Abstract [en]

    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 14.
    Ciftci, Baris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Harnefors, Lennart
    ABB Corporate Research.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Norrga, Staffan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nee, Hans-Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wireless Control of Modular Multilevel Converter Submodules With Communication Errors2022Ingår i: IEEE Transactions on Industrial Electronics, ISSN 0278-0046, E-ISSN 1557-9948, Vol. 69, nr 11, s. 11644-11653Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wireless control of modular multilevel converter (MMC) submodules can benefit from different points of view, such as lower converter cost and shorter installation time. In return for the advantages, the stochastic performance of wireless communication networks necessitates an advanced converter control system immune to the losses and delays of the wirelessly transmitted data. This paper proposes an advancement to the distributed control of MMCs to utilize in wireless submodule control. Using the proposed method, the operation of the MMC continues smoothly and uninterruptedly during wireless communication errors. The previously proposed submodule wireless control concept relies on implementing the modulation and individual submodule-capacitor-voltage control in the submodules using the insertion indices transmitted from a central controller. This paper takes the concept as a basis and introduces to synthesize the indices autonomously in the submodules during the communication errors. This new approach allows the MMC continue its operation when one, some, or all submodules suffer from communication errors for a limited time. The proposal is validated experimentally on a laboratory-scale MMC.

    Ladda ner fulltext (pdf)
    fulltext
  • 15.
    Dimitropoulos, Dimitrios
    et al.
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Bakhshizadeh, Mohammad Kazem
    Orsted Wind Power AS, DK-2820 Gentofte, Denmark..
    Kocewiak, Lukasz
    Orsted Wind Power AS, DK-2820 Gentofte, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark.
    Blaabjerg, Frede
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Impact of Synchronous Condensers' Ratings on Mitigating Subsynchronous Oscillations in Wind Farms2024Ingår i: Energies, E-ISSN 1996-1073, Vol. 17, nr 7, artikel-id 1730Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Subsynchronous oscillations have occurred in wind farms due to the high penetration of converter-based technology in power systems and may potentially lead to grid instability. As an effective solution, synchronous condensers, with their ability to control voltage and inject reactive power in the power system, are increasingly being adopted, as they can lead to the mitigation of such oscillations in weak grid conditions. However, the impact of synchronous condensers' power ratings on system stability is a topic that requires further investigation. In fact, an improper selection of a synchronous condenser's rating will not extinguish existing subsynchronous oscillations and may even cause the emergence of new oscillatory phenomena. This paper presents a novel examination of the impact that the synchronous condenser's power rating has on the small-signal stability of a wind farm with existing subsynchronous oscillations while being connected to a weak grid. The wind farm's model is developed using state-space modeling, centering on grid interconnection and incorporating the state-space submodel of a synchronous condenser to show its impact on subsynchronous oscillation mitigation. The stability analysis determines the optimal synchronous condenser's power ratings for suppressing these oscillations in the wind farm model. The findings are corroborated through time domain simulations and fast-Fourier transformation (FFT) analysis, which further validate the stability effects of a synchronous condenser's rating.

  • 16.
    Dimitropoulos, Dimitrios
    et al.
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark.
    Blaabjerg, Frede
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Stability Analysis in Multi-VSC (Voltage Source Converter) Systems of Wind Turbines2024Ingår i: Applied Sciences, E-ISSN 2076-3417, Vol. 14, nr 8, artikel-id 3519Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a holistic nonlinear state-space model of a system with multiple converters is developed, where the converters correspond to the wind turbines in a wind farm and are equipped with grid-following control. A novel generalized methodology is developed, based on the number of the system's converters, to compute the equilibrium points around which the model is linearized. This is a more solid approach compared with selecting operating points for linearizing the model or utilizing EMT simulation tools to estimate the system's steady state. The dynamics of both the inner and outer control loops of the power converters are included, as well as the dynamics of the electrical elements of the system and the digital time delay, in order to study the dynamic issues in both high- and low-frequency ranges. The system's stability is assessed through an eigenvalue-based stability analysis. A participation factor analysis is also used to give an insight into the interactions caused by the control topology of the converters. Time domain simulations and the corresponding frequency analysis are performed in order to validate the model for all the control interactions under study.

  • 17.
    Duan, Jinpei
    et al.
    Harbin Institute of Technology (Shenzhen), Power Electronics and Motion Control Research Center, Shenzhen, China, 518055; Peng Cheng Laboratory, Shenzhen, China.
    Zhang, Donglai
    Harbin Institute of Technology (Shenzhen), Power Electronics and Motion Control Research Center, Shenzhen, China, 518055; Peng Cheng Laboratory, Shenzhen, China.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Gu, Runan
    Harbin Institute of Technology (Shenzhen), Power Electronics and Motion Control Research Center, Shenzhen, China, 518055; Peng Cheng Laboratory, Shenzhen, China.
    Wang, Chao
    Beijing Institute of Spacecraft System Engineering, Beijing, China.
    Liu, Zhigang
    Beijing Institute of Spacecraft System Engineering, Beijing, China.
    Dual-Circulant Modulation for Modular Multilevel DC/DC Converters With Inherent Balance Capability2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 7, s. 7958-7963Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modular multilevel dc/dc converters (MMDC) have emerged recently for medium-voltage dc applications. Under single-circulant modulation, the submodule (SM) capacitor voltages in MMDC are found to be evenly divided only at some specific modulation coefficients. To obtain the inherent balance capability under all modulation coefficients and expand the application range of circulant modulation, a simple dual-circulant modulation is proposed in this letter. On the basis of single-circulant modulation, the self-balancing of the SM capacitor voltages is realized by using the additional switching patterns generated by a simple circulant permutation method. The theoretical analysis of the proposed method is presented, and the inherent balance capability of MMDC under the dual-circulant modulation method is verified by experiments.

  • 18.
    Fan, Bo
    et al.
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Liu, Teng
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Zhao, Fangzhou
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Wu, Heng
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    A Review of Current-Limiting Control of Grid-Forming Inverters Under Symmetrical Disturbances2022Ingår i: IEEE OPEN JOURNAL OF POWER ELECTRONICS, ISSN 2644-1314, Vol. 3, s. 955-969Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Grid-forming (GFM) inverters are recognized as a viable solution to increase the penetration of renewable energy in bulk power systems. However, they are physically different from synchronous generators in terms of overcurrent capability. To protect the power semiconductor devices and support the power grid under severe symmetrical disturbances, the GFM control systems should be able to achieve the following requirements: current magnitude limitation, fault current contribution, and fault recovery capability. Various current-limiting control methods are reported in the literature to fulfill these goals, including current limiters, virtual impedance, and voltage limiters. This paper presents an overview of those methods. Emerging challenges that need to be addressed, including temporary overcurrent, unspecified output current vector angle, undesired current saturation, and transient overvoltage, are pointed out. Comparative simulations are conducted to demonstrate the performance of different methods under grid voltage drops and phase jumps. Finally, open issues of current-limiting control methods for GFM inverters, including transient stability assessment, voltage source behavior under overcurrent conditions, and windup of voltage controllers, are shared.

  • 19.
    Fan, Bo
    et al.
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark.
    Fault Recovery Analysis of Grid-Forming Inverters With Priority-Based Current Limiters2023Ingår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 38, nr 6, s. 5102-5112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Grid-forming (GFM) inverters are required to operate robustly against grid faults. However, due to the limited over-current capability of inverters, current-limiting controls are usually applied to protect these semiconductor devices, which may prevent GFM inverters from a successful fault recovery. To understand this phenomenon, this study analyzes the fault recovery process of a GFM inverter with a priority-based current limiter. According to whether the GFM inverter can ensure transient stability and exit the current-limiting mode after fault clearance, three post-fault scenarios are identified, including normal operation, current limitation, and oscillations. Further, the impacts of the short-circuit ratio and control parameters on the post-fault behavior of GFM inverters are demonstrated. To illustrate the implications of these theoretical results, typical numerical examples are presented. Finally, the theoretical findings are validated through experimental tests.

  • 20.
    Gao, Guoqing
    et al.
    Aalborg Univ, DOE, Aalborg, Denmark..
    Wu, Heng
    Aalborg Univ, DOE, Aalborg, Denmark..
    Blaabjerg, Frede
    Aalborg Univ, DOE, Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Fault current control of MMC in HVDC-connected offshore wind farm: A coordinated perspective with current differential protection2023Ingår i: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 148, s. 108952-, artikel-id 108952Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The modular multilevel converter (MMC) based high-voltage dc (HVDC)-connected offshore wind farm (OWF) is power electronic converter dominated power system, where the conventional current differential protection may not operate effectively. Based on the basic operation principle of the current differential relay, this paper points out that the phase difference ((fidiff) of fault currents from MMC and OWF should be limited within a specific range, i.e. (-(fidiffmax, (fidiffmax), to guarantee the reliable tripping of the current differential relay. Yet, the highly control-dependent fault currents from the MMC and OWF could yield an arbitrary (fidiff that might beyond (-(fidiffmax, (fidiffmax), which leads to the possible malfunction of the current differential relay. To tackle this challenge, the coordinated control method of MMC is proposed to align the phase angle of its fault current with that of the OWF, such that (fidiff is an element of (-(fidiffmax, (fidiffmax) can be always guaranteed, so as the reliable operation of the current differential relay. Finally, the proposed coordinated control is verified by the electromagnetic transient (EMT) simulations in PSCAD and the real-time digital simulator (RTDS).

  • 21.
    Li, Helong
    et al.
    Hefei University of Technology, School of Electrical and Automation Engineering, Hefei, China..
    Zhao, Shuang
    Hefei University of Technology, School of Electrical and Automation Engineering, Hefei, China..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Ding, Lijian
    Hefei University of Technology, School of Electrical and Automation Engineering, Hefei, China..
    Mantooth, Homer Alan
    University of Arkansas, Department of Electrical Engineering, Fayetteville, AR, USA..
    Parallel Connection of Silicon Carbide MOSFETs - Challenges, Mechanism, and Solutions2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 8, s. 9731-9749Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power semiconductor devices are often connected in parallel to increase the current rating of the power conversion systems. However, due to mismatched circuit parameters or semiconductor fabrication discrepancies, the current of paralleled power semiconductor devices can be unbalanced, which potentially leads to accelerated aging and long-term reliability issues. The fast-switching speed of silicon carbide (SiC) devices aggravates this problem due to its higher sensitivity to parasitic parameters. Numerous efforts have been dedicated to analyzing and addressing the current imbalance issue of paralleling SiC devices. This article comprehensively summarizes and presents state-of-the-art research regarding the current imbalance in paralleled SiC devices. Degree of imbalance is proposed to comprehensively quantify the current mismatch. Starting with mechanism analysis, different types of current imbalance are categorized. Various device parameters and the package layout that impact the current distribution are investigated. The existing solutions including passive methods and active methods are concluded and categorized. This work also incorporates insight into the future development needs of high-power multichip SiC module packaging and driving technologies.

  • 22.
    Li, Yifei
    et al.
    Department of Energy, Aalborg University, Aalborg, Denmark.
    Wu, Heng
    Department of Energy, Aalborg University, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Impacts of inverter-based resources on directional elements during asymmetrical faults2023Ingår i: Proceedings 22nd Wind and Solar Integration Workshop, WIW 2023, Institution of Engineering and Technology (IET) , 2023, s. 400-405Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The large-scale integration of Inverter-Based Resources (IBRs) significantly alters the fault characteristics of synchronous generator-dominated power systems, posing a challenge to the conventional sequence component-based directional elements in the grid protection system. To reveal the impacts of IBRs on sequence component-based directional elements during asymmetrical faults, this paper first investigates the impacts of various priority modes of current reference generation. Subsequently, the impacts of control dynamics in the cases where the control scheme has not yet reached a steady state are investigated. It is found that the current reference generation and Phase-Locked Loop (PLL) dynamic can adversely affect the performance of directional elements. Electromagnetic transient (EMT) simulations are given to verify the theoretical analysis.

  • 23.
    Li, Yifei
    et al.
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Wu, Heng
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Xiong, Yongxin
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Current Reference Generation of Inverter-Based Resources During Asymmetrical Faults2023Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 1129-1136Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper analyzes the current reference generation of inverter-based resources (IBRs) during asymmetrical faults. It is revealed that the existing current generation methods are insufficient in maximizing the fault current contribution under different current priority modes. In this paper, a novel current reference generation approach is proposed to address this problem while simultaneously ensuring compliance with converter current limitations and grid codes. Electromagnetic transient (EMT) simulations are given to verify the proposed method.

  • 24.
    Li, Yifei
    et al.
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Wu, Heng
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Wu, Heng
    Aalborg University, Dept. of Energy, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Impacts of Current Reference Generation on Phase Selection Element2023Ingår i: 2023 8th IEEE Workshop on the Electronic Grid, eGRID 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the increasing integration of inverter-based resources (IBRs) into power systems, the fault characteristics of the power system can be altered, potentially affecting the performance of the traditional phase selection element (PSE). This paper first analyzes the fault characteristics of IBRs, then provides a theoretical examination of how these unique fault characteristics affect the performance of PSE. It is revealed current reference generation of IBRs will significantly impact the efficiency of PSE by altering the proportion of active current. Electromagnetic transient (EMT) simulations are given to verify the theoretical analysis.

  • 25.
    Li, Yufei
    et al.
    Princeton Univ, Princeton, NJ 08544 USA..
    Liao, Yicheng
    Energinet, Fredericia, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Nordström, Lars
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Mittal, Prateek
    Princeton Univ, Princeton, NJ 08544 USA..
    Chen, Minjie
    Princeton Univ, Princeton, NJ 08544 USA..
    Poor, H. Vincent
    Princeton Univ, Princeton, NJ 08544 USA..
    Neural Network Models and Transfer Learning for Impedance Modeling of Grid-Tied Inverters2022Ingår i: 2022 IEEE 13TH INTERNATIONAL SYMPOSIUM ON POWER ELECTRONICS FOR DISTRIBUTED GENERATION SYSTEMS (PEDG), Institute of Electrical and Electronics Engineers (IEEE) , 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    The future power grid will be supported by a large number of grid-tied inverters whose dynamics are critical for grid stability and power flow control. The operating conditions of these inverters vary across a wide range, leading to different small-signal impedances and different grid-interface behaviors. Analytical impedance models derived at specific operating points can hardly capture nonlinearities and nonidealities of the physical systems. The applicability of electromagnetic transient (EMT) simulations is often limited by the system complexity and the available computational resources. This paper applies neural network and transfer learning to impedance modeling of gridtied inverters. It is shown that a neural network (NN) trained by data automatically acquired from EMT simulations outperforms the one trained by traditional analytical models when unknown information exist in simulations. Pre-training the NN with analytically calculated data can greatly reduce the amount of simulation data needed to achieve good modeling results.

  • 26.
    Li, Yunwei Ryan
    et al.
    Univ Alberta, Edmonton, AB T6G 2R3, Canada..
    Agarwal, Vivek
    Indian Inst Technol, Mumbai 400076, India..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Editorial: Special Section on Patent-Related Short Articles2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 6, s. 6748-6749Artikel i tidskrift (Övrigt vetenskapligt)
  • 27.
    Li, Zejie
    et al.
    Aalborg University, Department of Energy (AAU Energy), Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg University, Department of Energy (AAU Energy), Aalborg, Denmark.
    Zhao, Fangzhou
    Aalborg University, Department of Energy (AAU Energy), Aalborg, Denmark.
    Munk-Nielsen, Stig
    Aalborg University, Department of Energy (AAU Energy), Aalborg, Denmark.
    Geske, Martin
    GE Power Conversion, Berlin, Germany.
    Grune, Rayk
    R&D Test Systems A/S, Berlin, Germany.
    Bo Ronnest Andersen, Daniel
    Eltwin A/S, Risskov, Denmark.
    Garnelo Rodriguez, Miguel
    R&D Test Systems A/S, Hinnerup, Denmark.
    Power-Hardware Design and Topologies of Converter-Based Grid Emulators for Wind Turbines2023Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, E-ISSN 2168-6785, Vol. 11, nr 5, s. 5001-5017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power-electronic-based grid emulators (GEs) emerge as a favorable method for testing grid-code compliances of wind turbines (WTs), thanks to their full controllability and improved efficiency. To accommodate the increasing power and voltage levels of WTs, scalability becomes a critical requirement for the topologies of converter-based GEs. This article identifies first the power rating of future GEs based on the system architecture and the evolution of WTs, followed by evaluating converter topologies of GEs for high scalability. Design considerations of power semiconductor devices, step-up transformers, dc chopper, and dc capacitors are also discussed for existing and prospective GEs.

  • 28.
    Li, Zejie
    et al.
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Zhao, Fangzhou
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark.;KTH Royal Inst Technol, Div Elect Power & Energy Syst, S-11428 Stockholm, Sweden..
    Munk-Nielsen, Stig
    Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Geske, Martin
    GE Power Convers, D-12277 Berlin, Germany..
    Grune, Rayk
    R&D Test Syst AS, D-13055 Berlin, Germany..
    Andersen, Daniel Bo Ronnest
    Knud Jepsen AS, DK-8382 Hinnerup, Denmark..
    Rodriguez, Miguel Garnelo
    Knud Jepsen AS, DK-8382 Hinnerup, Denmark..
    Medium-Voltage Megawatt Power-Electronic-Based Grid Emulators: Testing Capability Requirements and Dynamics Challenges-A Review2024Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, E-ISSN 2168-6785, Vol. 12, nr 2, s. 1545-1559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power-electronic-based grid emulators are emerging as a promising way to test the grid-code compliance of renewable energy resources. Yet, the ever-increasing power and voltage levels of device under test (DUT) pose new requirements and challenges to power-electronic-based grid emulators. This article first gives an overview of testing capability requirements based on the recent grid codes and standards and then discusses the resulted dynamic interactions and solutions for power-electronic-based grid emulators. Perspectives on the open issues and emerging trends of grid emulators are finally shared.

  • 29.
    Liao, Yicheng
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Energinet, Department of Electrical System Design, Fredericia, Denmark, 7000.
    Li, Yufei
    Princeton University, Department of Electrical and Computer Engineering, Princeton, NJ, USA, 08544.
    Chen, Minjie
    Princeton University, Department of Electrical and Computer Engineering, Princeton, NJ, USA, 08544.
    Nordström, Lars
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Mittal, Prateek
    Princeton University, Department of Electrical and Computer Engineering, Princeton, NJ, USA, 08544.
    Poor, H. Vincent
    Princeton University, Department of Electrical and Computer Engineering, Princeton, NJ, USA, 08544.
    Neural Network Design for Impedance Modeling of Power Electronic Systems Based on Latent Features2024Ingår i: IEEE Transactions on Neural Networks and Learning Systems, ISSN 2162-237X, E-ISSN 2162-2388, Vol. 35, nr 5, s. 5968-5980Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Data-driven approaches are promising to address the modeling issues of modern power electronics-based power systems, due to the black-box feature. Frequency-domain analysis has been applied to address the emerging small-signal oscillation issues caused by converter control interactions. However, the frequency-domain model of a power electronic system is linearized around a specific operating condition. It thus requires measurement or identification of frequency-domain models repeatedly at many operating points (OPs) due to the wide operation range of the power systems, which brings significant computation and data burden. This article addresses this challenge by developing a deep learning approach using multilayer feedforward neural networks (FNNs) to train the frequency-domain impedance model of power electronic systems that is continuous of OP. Distinguished from the prior neural network designs relying on trial-and-error and sufficient data size, this article proposes to design the FNN based on latent features of power electronic systems, i.e., the number of system poles and zeros. To further investigate the impacts of data quantity and quality, learning procedures from a small dataset are developed, and K-medoids clustering based on dynamic time warping is used to reveal insights into multivariable sensitivity, which helps improve the data quality. The proposed approaches for the FNN design and learning have been proven simple, effective, and optimal based on case studies on a power electronic converter, and future prospects in its industrial applications are also discussed.

  • 30.
    Liao, Yicheng
    et al.
    Energinet, Elnetanalyse, DK-7000 Fredericia, Denmark..
    Sandberg, Henrik
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Vector-Norm Based Truncation of Harmonic Transfer Functions in Black-Box Electronic Power Systems2022Ingår i: IEEE OPEN JOURNAL OF THE INDUSTRIAL ELECTRONICS SOCIETY, ISSN 2644-1284, Vol. 3, s. 163-173Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power systems equipped with power electronic converters can be modeled by harmonic transfer functions (HTFs) in a black-box manner for dynamic analysis. This paper studies the truncation of HTFs. It is proposed to define the gain function of an HTF as the norm of its central-column vector. Then, the error bound of the gain function in relation to the truncation order is explicitly derived, which can be used as an indicator for the HTF truncation. Compared with existing solutions, the proposed method is practical in truncating black-box systems with unknown internal parameters, since the truncation error bound can be estimated by the central-column elements of the HTF, which can be easily measured through frequency scan. The truncation approach is finally verified on a three-phase electronic power system by electromagnetic transient simulations.

  • 31.
    Liao, Yicheng
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmar.
    Wu, Heng
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark.
    Ndreko, Mario
    TenneT TSO GmbH, Elect Syst Design, D-95448 Bayreuth, Germany..
    Dimitrovski, Robert
    TenneT TSO GmbH, Elect Syst Design, D-95448 Bayreuth, Germany..
    Winter, Wilhelm
    TenneT TSO GmbH, Elect Syst Design, D-95448 Bayreuth, Germany..
    Stability and Sensitivity Analysis of Multi-Vendor, Multi-Terminal HVDC Systems2023Ingår i: IEEE OPEN JOURNAL OF POWER ELECTRONICS, ISSN 2644-1314, Vol. 4, s. 52-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multi-terminal HVDC projects are increasingly developed in recent years to enhance the flexibility of energy transmission. Differing from the point-to-point HVDC systems, it is more challenging to design the multi-terminal HVDC system and ensure stable interoperability among converter systems, especially when the converters are manufactured from different vendors. Although impedance-based stability analysis allows for analyzing such systems based on black-box models, it is still difficult to utilize those black-box models to identify the root cause of potential instability. To tackle this challenge, this paper proposes a multi-level sensitivity analysis approach using frequency-domain sensitivity functions based on the impedance-based stability criterion. The proposed method differs from the classical sensitivity analysis based on state-space or transfer-function models, as it is purely based on black-box impedance models. Case studies on a four-terminal HVDC system are carried out for stability and sensitivity analysis based on the impedance measurement in PSCAD, through which the most sensitive HVDC station can be identified. The proposed theory and the analyzed results are finally validated by electromagnetic transient simulations.

  • 32.
    Luo, Cheng
    et al.
    Xi An Jiao Tong Univ, Sch Elect Engn, State Key Lab Elect Insulat & Power Equipment, Xian 710049, Peoples R China.;Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Liu, Teng
    Elect Power Res Inst China Southern Power Grid, Guangzhou 510663, Peoples R China..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, Dept Energy AAU Energy, DK-9220 Aalborg, Denmark..
    Ma, Xikui
    Xi An Jiao Tong Univ, Sch Elect Engn, State Key Lab Elect Insulat & Power Equipment, Xian 710049, Peoples R China..
    Design-Oriented Analysis of DC-Link Voltage Control for Transient Stability of Grid-Forming Inverters2024Ingår i: IEEE Transactions on Industrial Electronics, ISSN 0278-0046, E-ISSN 1557-9948, Vol. 71, nr 4, s. 3698-3707Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article analyzes the parametric effect of the dc-link voltage controller (DVC) on the transient stability of grid-forming (GFM) inverters. It is found that the decrease of the proportional gain of DVC may lead to the loss of synchronism (LOS) even if the system is locally stable at the new equilibrium point (EP) after disturbance. Its physical insight is attributed to the unstable limit cycle (ULC) in the phase space according to the bifurcation theory. The GFM inverters whose operating point locates outside of ULC will lose synchronism with the grid. The decrease of the proportional gain of DVC will diminish the ULC, resulting in fewer operating points converging to the new EP and a higher risk of LOS. This bifurcation-based analysis provides a novel perspective for investigating the mechanism of parametric effect for the high-order nonlinear system, which is the article's main contribution. The parametric effect of the integral gain of DVC is also analyzed. A holistic parametric space partition for designing DVC is then drawn from the analysis, and a parametric configuration guideline is provided. The theoretical findings are validated by experimental tests.

  • 33.
    Luo, Cheng
    et al.
    Xi An Jiao Tong Univ, Sch Elect Engn, State Key Lab Elect Insulat & Power Equipment, Xian 710049, Peoples R China.;Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Ma, Xikui
    Xi An Jiao Tong Univ, Sch Elect Engn, State Key Lab Elect Insulat & Power Equipment, Xian 710049, Peoples R China..
    Liu, Teng
    China Southern Power Grid, Elect Power Res Inst, Guangzhou 510663, Peoples R China..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    A Flexible Saturation Limiter for DC-Link Voltage Control of Grid-Forming Inverters With Enhanced Transient Stability2023Ingår i: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 38, nr 4, s. 2514-2524Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article analyzes the influence of the saturation limiter used with dc-link voltage control (DVC) on the transient stability of grid-forming (GFM) inverters and proposes a flexible saturation limiter to alleviate its adverse impact. First, it is found that the conventional saturation limiter (CSL) can enhance transient stability. Yet, it would boost the dc-link voltage or even trigger overvoltage protection, especially when the threshold value of CSL is small. To tackle the adverse impact of CSL on dc-link voltage, a flexible saturation limiter is proposed, which only begins to limit the active power reference when the derivative of dc-link voltage turns from positive to negative (the dc-link voltage reaches its peak value at this instant). Finally, experimental tests confirm the effectiveness of the scheme.

  • 34.
    Luo, Cheng
    et al.
    Xi'an Jiaotong University, State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an, China, 710049; Aalborg University, AAU Energy, Aalborg, Denmark.
    Ma, Xikui
    Xi'an Jiaotong University, State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an, China.
    Liu, Teng
    Electric Power Research Institute of China Southern Power Grid, Guangzhou, China.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg University, AAU Energy, Aalborg, Denmark.
    Adaptive-Output-Voltage-Regulation-Based Solution for the DC-Link Undervoltage of Grid- Forming Inverters2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 10, s. 12559-12569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article proposes an adaptive-output-voltage-regulation (AOVR)-based solution to alleviate the dc-link undervoltage for grid-forming (GFM) inverters. First, it is shown that large disturbances may cause the dc-link undervoltage for GFM inverters threatening the safe operation of the system. To tackle this issue, an AOVR-based control strategy is proposed, whose main idea is to reduce the output voltage of the GFM inverter and also speed up the dynamic process of the power angle by intentionally enlarging the frequency deviation of the active power control loop. By doing so, the dc-link output energy will reduce to avoid possible undervoltage. The parameter design of the proposed method is based on the overmodulation constraints, and an auxiliary module is configured for the low-voltage-ride-through (LVRT) requirements. The applicability of the proposed solution is checked when considering the current limitation. The pros of the proposed solution are also depicted when compared with state-of-art solutions. The effectiveness of the proposed control strategy is finally confirmed by the experimental tests.

  • 35.
    Mudalige, Anuradha
    et al.
    Kiel University, Chair of Power Electronics, Kiel, Germany.
    Wu, Heng
    Aalborg University, Department of Energy, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Langwasser, Marius
    Kiel University, Chair of Power Electronics, Kiel, Germany.
    Liserre, Marco
    Kiel University, Chair of Power Electronics, Kiel, Germany.
    Influence of the reactive power control loop on network frequency perturbation plot2023Ingår i: PEDG 2023: 2023 IEEE 14th International Symposium on Power Electronics for Distributed Generation Systems, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 814-820Konferensbidrag (Refereegranskat)
    Abstract [en]

    Grid Forming (GFM) inverters are valuable assets for enabling sustainable power systems. Network Frequency Perturbation (NFP) plot could serve as a valuable tool for evaluating the behaviour of a GFM inverter's active power control (APC) loop. NFP plot has been recommended in the recent grid code modification by National Grid ESO as a document to be submitted by a grid forming (GFM) plant operator for compliance testing purposes. In a grid connected GFM inverter, it is well known that the APC and reactive power control (RPC) loops are inherently coupled with each other. However, state of the art guidelines on producing and interpreting an NFP plot have completely disregarded the influence of this coupling effect in an attempt to simplify the analysis. In this paper, a systematic analysis is presented which identifies the conditions under which such a simplification could be valid, or could otherwise introduce significant influence on the NFP plot. Simulation results are presented validating the theoretical analysis.

  • 36.
    Ojo, Olorunfemi
    et al.
    Tennessee Tech University, USA.
    Lu, Xiaonan
    Purdue University, USA.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Chen, Minjie
    Princeton University, USA.
    Amirabadi, Mahshid
    Northeastern University, USA.
    Rallabandi, Vandana
    Oak Ridge National Laboratory, USA.
    Wang, Jin
    Ohio State University, USA.
    Gachovska, Tanya
    MDA, Canada.
    Welcome From: Technical Program Chairs2023Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Konferensbidrag (Refereegranskat)
  • 37.
    Qoria, Taoufik
    et al.
    Maschinenfabr Reinhausen Gmbh, Regenesburg, Germany..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Kadri, Riad
    Univ Lille, Arts & Metiers Inst Technol, Cent Lille, Yncrea Hauts Defrance,ULR 2697,Lab Electrotech & E, F-59000 Lille, France..
    Grid-forming control VSC-based including current limitation and re-synchronization functions to deal with symmetrical and asymmetrical faults2023Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 223, artikel-id 109647Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Grid-forming converters operate as voltage sources behind impedance. This property makes them robust against Short-Circuit Ratio (SCR) variation, but vulnerable against large grid disturbances. As a precaution, grid forming converters have to embed adequate control algorithms to ensure a stable system operation under various grid conditions, to deal with excessive overloadings mainly caused by faults, and to guarantee a stable re-synchronization after fault clearance. These expectations have been met in previous works considering balanced conditions. Nevertheless, the extension of the grid-forming control to deal with unbalanced grid conditions considering current limitation and angular stability is a point rarely discussed in the literature. To fill this research gap, this paper proposes an Extended Power Synchronization Method (EPSM) that allows the system to operate under balanced and unbalanced grid conditions while meeting the Fault Ride-Through requirements (FRT). The proposed method is a direct voltage control-based, which embeds a threshold current control loop, which is enabled only when a fault is detected. Additionally, the control is equipped with an algorithm that modifies the active power control during faults to aid the power converter to remain synchronized after fault clearance. The effectiveness of the proposed control has been demonstrated through time-domain simulations.

  • 38.
    Qoria, Taoufik
    et al.
    Maschinenfabrik Reinhausen, Medium Voltage Power Electronics R&D Department, Regensburg, Germany, 93059.
    Wu, Heng
    Aalborg Universitet Teknisk-Naturvidenskabelige Fakultet, Department of Energy Technology, Aalborg, Denmark, 9220.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Colak, Ilknur
    Schneider Electric, Department of Power Electronics, Rueil-Malmaison, France, 92500.
    Variable Virtual Impedance-Based Overcurrent Protection for Grid-Forming Inverters: Small-Signal, Large-Signal Analysis and Improvement2023Ingår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 14, nr 5, s. 3324-3336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Grid-forming inverters are sensitive to large grid disturbances that may engender overcurrent due to their voltage source behavior. To overcome this critical issue and ensure the safety of the system, current limitation techniques have to be implemented. In this context, the variable virtual impedance (VI) appears as a suitable solution for this problem. The design of the variable virtual impedance basically rests on static considerations, while, its impact on the system stability and dynamics considering both small-signal and large-signal aspects can be significant. This paper proposes small-signal and nonlinear power models to assess the impact of the virtual impedance parameters on the grid current dynamics and on the angle stability. Thanks to the proposed approach, it has been demonstrated that the virtual impedance ratio σ _X_VI/R_VI has a contradictory effect on the system dynamics and the transient stability, i.e., a resistive virtual impedance results in a well-damped current response but a very limited transient stability margin, while an inductive virtual impedance results in a poorly-damped current response but an acceptable transient stability margin. Based on that, it has been concluded that the conventional virtual impedance cannot cope at once with the current dynamic performances and the transient stability. To overcome this constraint, a Variable Transient Virtual Resistance (VTVR) has been proposed as an additional degree of freedom to vary σ _X_VIR_VI. It decreases σ _X_VI/R_VI in the transient to damp the current response and it increases σ _X_VIR_VI in the quasi-static and steady-state to guarantee the maximum angle stability margin allowed by the variable virtual impedance. The effectiveness of the proposed control has been proven through time-domain simulations.

  • 39.
    Wang, Xinshuo
    et al.
    Aalborg University, Energy Department, Denmark.
    Wu, Heng
    Aalborg University, Energy Department, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg University, Energy Department, Denmark.
    Transient Overvoltage Analysis of Grid-Following VSCs during Fault Recovery2023Ingår i: ICPE 2023-ECCE Asia: 11th International Conference on Power Electronics - ECCE Asia, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 2404-2409Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current grid code has explicit requirement on the fault current injection profile of grid-following voltage-source converters (GFL-VSCs), i.e., the output reactive current of GFL-VSC needs to be proportional to voltage- magnitude deviation at the point of connection (PoC) until its current limitation is reached. This article points out that such way of injecting the fault current may result in transient overvoltage (TOV) at the PoC during fault recovery, and the rate of change of current reference of GFL-VSC is critical to the duration of TOV. Moreover, a method for estimating the maximum magnitude of TOV is presented, which provides an intuitive insight for the TOV phenomenon.

  • 40.
    Wang, Zhihao
    et al.
    Shandong Univ, Sch Elect Engn, Key Lab Power Syst Intelligent Dispatch & Control, Minist Educ, Jinan 250061, Peoples R China..
    Zhu, Guofang
    Shandong Univ, Sch Elect Engn, Key Lab Power Syst Intelligent Dispatch & Control, Minist Educ, Jinan 250061, Peoples R China..
    Wu, Heng
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Gao, Xuesong
    Shandong Univ, Sch Elect Engn, Key Lab Power Syst Intelligent Dispatch & Control, Minist Educ, Jinan 250061, Peoples R China..
    Ding, Lei
    Shandong Univ, Sch Elect Engn, Key Lab Power Syst Intelligent Dispatch & Control, Minist Educ, Jinan 250061, Peoples R China..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Current Reference Control Scheme of Voltage Source Converters to Ensure the Existence of Stable Equilibrium Points During Grid Fault2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 9, s. 10750-10765Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Maintaining synchronization with the grid during fault ride-through (FRT) is essential for grid-connected voltage source converters (VSCs). However, improper current references can lead to a loss of synchronization during FRT due to the nonexistence of stable equilibrium points (SEPs). While the mechanism of SEPs has been explained, the development of control schemes ensuring their existence remains challenging due to the difficulty of obtaining real-time grid parameters during FRT. To address this issue, this article proposes a novel current reference control scheme that only requires prefault grid parameters. By analyzing the changes in grid parameters caused by faults and characterizing the correspondence between the during-fault and prefault grid parameters, a voltage-dependent current reference control scheme is proposed. Since no real-time grid parameter estimation is needed during FRT, the proposed control scheme is practical and easy to implement. Simulation studies using DIgSILENT PowerFactory demonstrate that the proposed control scheme enables the VSC to maintain synchronization with the grid under the conditions of short-circuit ratio equaling 1.3 and grid voltage dropping to 0.1 p.u. Moreover, experiments further verify the effectiveness and feasibility of the proposed control scheme.

  • 41.
    Wu, Heng
    et al.
    Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, AAU Energy, DK-9220 Aalborg, Denmark..
    Control of Grid-Forming VSCs: A Perspective of Adaptive FastSlow Internal Voltage Source2023Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 38, nr 8, s. 10151-10169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Grid-forming (GFM) capability requirements are increasingly imposed on grid-connected voltage-source converters (VSCs). Under large grid disturbances, GFM-VSCs need to remain stable while providing GFM services. Yet, such objectives, as pointed out in this article, inherently lead to conflicting requirements on the dynamics of the internal voltage source (IVS) of GFM-VSCs, i.e., the fast IVS dynamics is needed to avoid the loss of synchronism with the grid, whereas the slow IVS dynamics is preferred for maintaining GFM capability. To tackle this challenge, an adaptive fast/slow IVS control is proposed, which switches GFM-VSC between fast and slow IVS dynamics based on system needs. The proposed method enhances the transient stability of GFM-VSC while maximizing its capability of providing GFM service. Further, the approach is robust to different grid strengths and different types of grid disturbances. The experimental results verify the theoretical findings and the effectiveness of the proposed control method.

  • 42.
    Wu, Heng
    et al.
    Aalborg Univ, Dept Energy, Aalborg, Denmark.
    Zhao, Fangzhou
    Aalborg Univ, Dept Energy, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg Univ, Dept Energy, Aalborg, Denmark.
    A Survey on Impedance-Based Dynamics Analysis Method for Inverter-Based Resources2023Ingår i: IEEE POWER ELECTRONICS MAGAZINE, ISSN 2329-9207, Vol. 10, nr 3, s. 43-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Impedance-based method has been increasingly adopted to assess the stability of inverter-based resources (IBRs). To get a better view of the state-of-the-art and challenges for implementing the impedance-based dynamic analysis, a survey with general/specific questions has been initiated by IEEE Task Force on Frequency-Domain Modeling and Dynamic Analysis of High-Voltage Direct Current (HVDC) and Flexible AC Transmission System (FACTS). The feedbacks are collected from universities, national labs, transmission system operators (TSOs), power plant developers, as well as IBR vendors. It is interesting to note that while many common understandings have been established in practices, certain gaps still exist among different stakeholders. This article intends to bridge this gap by sharing a summary of the survey, including questionnaires, responses from different stakeholders, and the analysis of survey results. The challenges for different stakeholders using impedance-based method are identified, which shed a light on the future research work.

  • 43.
    Wu, Yang
    et al.
    Aalborg Univeristy, Department of Energy, Aalborg, Denmark.
    Wu, Heng
    Aalborg Univeristy, Department of Energy, Aalborg, Denmark.
    Cheng, Li
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Zhou, Jianyu
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Zhou, Zichao
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Chen, Minjie
    Princeton University, Department of Electrical and Computer Engineering, Princeton, NJ, USA.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Impedance Profile Prediction for Grid-Connected VSCs based on Feature Extraction2024Ingår i: 2024 IEEE Applied Power Electronics Conference and Exposition, APEC 2024, Institute of Electrical and Electronics Engineers (IEEE) , 2024, s. 1627-1632Konferensbidrag (Refereegranskat)
    Abstract [en]

    Impedance-based stability analysis has been widely adopted for voltage source converters (VSCs). Considering unknown controller parameters, impedance measurement based on frequency scan is always required for stability evaluation, which endures complicated implementation and can only be conducted under small amount of stable operating conditions. To solve this problem, a novel impedance profile prediction method for grid-connected VSCs has been proposed. A combined structure of stacked autoencoder (AE) and principal component analysis (PCA) is firstly proposed to extract VSC admittance feature under stable operating points, and a comprehensive VSC admittance set can be further predicted through searching on an enlarged feature space with unstable scenarios included. The stability can then be evaluated on the predicted VSC admittances with a stability boundary derived. Simulations and experiments prove the effectiveness of the proposed method.

  • 44.
    Xie, Xiaorong
    et al.
    State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
    Shair, Jan
    State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
    Beerten, Jef
    Department of Electrical Engineering, KU Leuven, Leuven, Belgium; Energyville, Genk, Belgium.
    Fan, Lingling
    Department of Electrical Engineering, University of South Florida, Tampa, FL, USA.
    Gomis-Bellmunt, Oriol
    CITCEA, Universitat Politecnica de Catalunya, Barcelona, Spain.
    Vorobev, Petr
    Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, Bld. 1, Moscow 121205, Russia.
    Preece, Robin
    Department of Electrical and Electronic Engineering, The University of Manchester, M13 9PL, UK.
    Shah, Shahil
    National Renewable Energy Laboratory, Golden, CO, USA.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Yang
    Sichuan University, China.
    Terzija, Vladimir
    Center for Energy Science and Technology, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, Bld. 1, Moscow 121205, Russia.
    Guest Editorial: Control interactions in power electronic converter dominated power systems2024Ingår i: International Journal of Electrical Power & Energy Systems, ISSN 0142-0615, E-ISSN 1879-3517, Vol. 155, artikel-id 109553Artikel, forskningsöversikt (Refereegranskat)
  • 45.
    Yang, Yong
    et al.
    Aalborg University, Department of Energy Technology, Aalborg, Denmark.
    Zhou, Zhichao
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Programvaruteknik och datorsystem, SCS.
    Zhao, Liang
    Aalborg University, Department of Energy Technology, Aalborg, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Controller Sensitivity-Based Shaping Method for Grid Forming Inverter2023Ingår i: 2023 IEEE Energy Conversion Congress and Exposition, ECCE 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023, s. 6273-6278Konferensbidrag (Refereegranskat)
    Abstract [en]

    Parameter-based damping ratio sensitivity (DRS) is usually used for designing multi-loop complex control systems in grid-forming (GFM) inverters. However, it is found that this method will be affected not only by the interactions among parameters in a controller, but also by the change of the parameter itself, which makes the parameter design based on the parameter-based DRS unreliable. To address these issues, each controller is considered as a whole, which avoids the interactions among controller parameters in a controller. Then, the controller-based determinant sensitivity (DS) that calculates the sensitivity of each controller to system stability is proposed for designing the control system, which will not be affected by interactions among parameters since the sensitivity is calculated at the controller level. Then, combined with the proposed solution, a controller shaping method is also presented, which can improve system stability by shaping the controller. Finally, the effectiveness of the proposed scheme is validated through experimental results.

  • 46.
    Yang, Zhiqing
    et al.
    Hefei University of Technology, School of Electrical Engineering and Automation, Hefei, China, 230009.
    He, Shan
    Aalborg University, Department of Energy, Aalborg, Denmark, 9220.
    Zhou, Dao
    Aalborg University, Department of Energy, Aalborg, Denmark, 9220.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. Aalborg University, Department of Energy, Aalborg, Denmark, 9220.
    De Doncker, Rik W.
    Institute for Power Generation and Storage Systems, RWTH Aachen University, E. ON Energy Research Center, Aachen, Germany, 52074.
    Blaabjerg, Frede
    Aalborg University, Department of Energy, Aalborg, Denmark, 9220.
    Ding, Lijian
    Hefei University of Technology, School of Electrical Engineering and Automation, Hefei, China, 230009.
    Wideband Dissipativity Enhancement for Grid-Following VSC Utilizing Capacitor Voltage Feedforward2023Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, E-ISSN 2168-6785, Vol. 11, nr 3, s. 3138-3151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Frequency-domain dissipativity of the converter admittance provides an intuitive approach to analyze wideband resonances due to the interactions with the grid. Although the reasons for high- and low-frequency resonances are different, it is found that the proportional capacitor voltage feedforward (CVF) can affect and reshape the converter admittance in a wide frequency range. To enhance wideband dissipativity under a weak/capacitive grid, a proportional-integral (PI)-derivative CVF is proposed in this article. Specifically, high-frequency dissipativity can be guaranteed through the multisampling control (MSC) with proportional-derivative CVF. The low-frequency nondissipative region caused by the phase-locked loop (PLL) and proportional CVF can be compensated through multiorder integrations. In light of grid frequency disturbances, modified integrators are further proposed for the multiorder integrations. The proposed method also applies to the conventional double-sampling control (DSC) with regard to the low-frequency dissipativity enhancement. Finally, experiments validate the proposed control method.

  • 47.
    Zhan, Changjiang
    et al.
    NR Electric Co. Ltd., Nanjing 211102, Jiangsu Province, China, Jiangsu Province.
    Wu, Heng
    AAU Energy, Aalborg University, Aalborg 9220, Denmark.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Tian, Jie
    NR Electric Co. Ltd., Nanjing 211102, Jiangsu Province, China, Jiangsu Province.
    Wang, Xinbao
    NR Electric Co. Ltd., Nanjing 211102, Jiangsu Province, China, Jiangsu Province.
    Lu, Yu
    NR Electric Co. Ltd., Nanjing 211102, Jiangsu Province, China, Jiangsu Province.
    An Overview of Stability Studies of Grid-forming Voltage Source Converters2023Ingår i: Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering, ISSN 0258-8013, Vol. 43, nr 6, s. 2339-2358Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Unlike grid-following converters, the grid-forming converter is operated as a synchronous voltage source, which can effectively improve the stability of power-electronics-dominated power systems, and hence, has attracted much research attention in recent years. As a basis of the large-scale implementation of grid-forming converters, there should be an in-depth understanding of its stability under different grid strengths as well as different grid disturbances. This article performs a comprehensive overview of the stability studies of grid-forming converters from the perspective of existence of equilibrium points, small-signal stability, and transient stability. On top of this, stabilization control solutions of grid-forming converters are also summarized. In the end, perspectives on the prospects and challenges of stability analysis of grid-forming converters are shared.

  • 48.
    Zhang, Hongyang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. ABB, Power Grids Div, S-72164 Västerås, Sweden.
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik. ABB, Corp Res, S-72178 Västerås, Sweden..
    Wang, Xiongfei
    Aalborg Univ, Dept Energy Technol, DK-9220 Aalborg, Denmark..
    Gong, Hong
    Aalborg Univ, Dept Energy Technol, DK-9220 Aalborg, Denmark..
    Hasler, Jean-Philippe
    ABB, Power Grids Div, S-72164 Västerås, Sweden..
    Stability Analysis of Grid-Connected Voltage-Source Converters Using SISO Modeling2019Ingår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 34, nr 8, s. 8104-8117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interaction of a grid-connected voltage-source converter with a weak grid is of significant interest. In this paper, the converter together with the grid impedance is modeled as a single-input single-output (SISO) system. Provided that certain assumptions hold, this allows us to apply the standard SISO Nyquist stability criterion for stability analysis and controller design. The derivedmodel is verified against time-domain simulations and experiments. Themethod facilitates the design of the converter control system with adequate stability margins.

  • 49.
    Zhang, Hongyang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Harnefors, Lennart
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Hasler, Jean-Philippe
    Östlund, Stefan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Danielsson, Christer
    Gong, Hong
    Loop-at-a-Time Stability Analysis for Grid-Connected Voltage-Source Converters2021Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, E-ISSN 2168-6785, Vol. 9, nr 5, s. 5807-5821Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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.

  • 50.
    Zhang, Hongyang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknik, Elkraftteknik.
    Wang, Xiongfei
    Aalborg Univ, Dept Energy Technol, Aalborg, Denmark..
    A Closed-Loop Model for Stability Analysis of Grid-Connected Voltage-Source Converters2018Ingår i: 2018 IEEE INTERNATIONAL POWER ELECTRONICS AND APPLICATION CONFERENCE AND EXPOSITION (PEAC), IEEE , 2018, s. 975-980Konferensbidrag (Refereegranskat)
    Abstract [en]

    With an increasing number of grid-connected voltage-source converters in the power system, the stability analysis for the converter-grid interactions is of great interest. This paper proposes a linearized closed-loop model for predicting such stability problems, especially for those occurring under weak-grid conditions. Differing from the other known modeling approaches, a closed-loop model is constructed based on the transfer functions and it contains the control functions as well as the grid impedance. The stability and the individual controller impact can be assessed by the poles and zeros of the closed-loop transfer functions. Lastly, the linearized model is validated against the corresponding time-domain simulations and its excellent accuracy is proofed.

12 1 - 50 av 69
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf