Arm Current Control Strategy for MMC-HVDC Under Unbalanced Conditions

Liang, Yingyu; Liu, Jianzheng; Zhang, Tao; Yang, Qixun

doi:10.1109/tpwrd.2016.2554620

Cited by 74 publications

(47 citation statements)

References 22 publications

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“…Since the analysis and control of MMCs is currently being widely studied in the scientific community, several different methods have been proposed for controlling the circulating currents when operating under unbalanced grid voltage conditions [14]- [16], [18]- [20], [22]- [25]. However, many of the these proposed control strategies rely on a Circulating Current Suppression Controller (CCSC) and/or other control loops implemented in a synchronously rotating reference frame.…”

Section: Context and Contributionsmentioning

confidence: 99%

“…For instance, the grid synchronization mechanism based on the DSOGI-QSG is inherently frequency-adaptive, and can be extended to include harmonic sequence decomposition, as proposed in [7]. Similarly, strategies for limiting the power flow and current references resulting from (25) can be introduced to ensure safe operation of the converter during severe ac-side grid faults, as discussed in [5], [9], [39].…”

Section: B Ac-side Current Reference Calculation and Controlmentioning

confidence: 99%

“…From the equation for the circulating current reference i Σ ‡ k given in (24), and the equation for the ac-side current reference i Δ * k given in (25), it is clear that it is possible to define the dc power reference P * dc and the ac power reference P * ac separately as explicit signals within the control system. However, to preserve the system stability only one of these references can be used to define the steady-state power flow of the converter, while the other reference must be utilized to compensate for…”

Section: Ac-and Dc-side Power Referencesmentioning

confidence: 99%

See 2 more Smart Citations

Optimal Shaping of the MMC Circulating Currents for Preventing AC-Side Power Oscillations From Propagating Into HVdc Grids

Bergna-Diaz

Suul

Berne

et al. 2019

IEEE J. Emerg. Sel. Topics Power Electron.

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A constrained optimization problem based on the Lagrange multipliers method is formulated to derive the circulating current references of Modular Multilevel Converters (MMC) directly in abc coordinates. The resulting analytic expressions for calculating the circulating current reference signals are designed to eliminate oscillations in the dc-side power flow, independently from the ac-side operation of the MMC. As a result of the constrained optimization, the circulating currents are shaped to optimally utilize the degrees of freedom provided by the internal energy buffering capacity of the MMC, to effectively decouple the ac grid conditions from the dc bus. This property of the proposed control method makes it especially suitable for preventing oscillations due to unbalanced ac grid voltage conditions from propagating into multi-terminal HVDC systems. It is shown that the power flow at the dc-side of the MMC will be most effectively decoupled from ac-side transients if the desired steady-state power flow is imposed by acting directly on the circulating current references instead of by acting on the acside current references. The operation of an MMC controlled by the proposed approach is demonstrated by simulation studies, verifying the ability of keeping the dc power flow free of second harmonic oscillations, independently of the power control objectives applied for calculating the ac-side current references of the converter.

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Section: Context and Contributionsmentioning

confidence: 99%

Section: B Ac-side Current Reference Calculation and Controlmentioning

confidence: 99%

Section: Ac-and Dc-side Power Referencesmentioning

confidence: 99%

See 1 more Smart Citation

Optimal Shaping of the MMC Circulating Currents for Preventing AC-Side Power Oscillations From Propagating Into HVdc Grids

Bergna-Diaz

Suul

Berne

et al. 2019

IEEE J. Emerg. Sel. Topics Power Electron.

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“…Dynamic representation of MMC can be expressed by the following second‐order state‐space model by substituting into and as introduced in Liang et al

\frac{d x}{d t} = A x + B u + d,

where x and u denote the output state vector and input vector, respectively. d denotes the disturbance vector, and A and B are coefficient matrices.…”

Section: Circuit Topology and Modellingmentioning

confidence: 99%

“…Arm current control enables to control both terminal voltages and currents for DC and AC side of MMC. Arm current control scheme based on a decoupler and proportional integral controller with vector proportional integral controller is presented in Liang et al under unbalanced conditions. The circulating currents can be suppressed, and AC‐side current can be controlled through suggested control method.…”

Section: Control Conceptmentioning

confidence: 99%

Recent contributions and future prospects of the modular multilevel converters: A comprehensive review

Kurtoğlu

Eroğlu

Arslan

et al. 2018

Int Trans Electr Energ Syst

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Summary The modular multilevel converters (MMCs) are frequently preferred for medium and high power energy conversion systems thanks to their modular structure and high quality output waveform. The remarkable studies related to the MMC have been carried out in recent years, which are mainly focused on its topology, control, or application. In this paper, MMC circuit topologies consisting of traditional submodule cells and new proposed configurations are introduced, and their control process, modulation techniques, and application areas are discussed in order to provide the readers the current state of the art of MMC technology. A wide part of this article is devoted to demonstrate the recent contributions arising in MMC studies. In this context, this paper not only outlines the circuit topology, control objectives, and applications of the MMC but also presents a comprehensive review, principally in terms of the latest developments of it. Ultimately, detailed proposals and new possible topics are provided to drive future expectations of MMC technology.

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Control of MMCs Under AC Grid Faults

2023

Modular Multilevel Converters

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Arm Current Control Strategy for MMC-HVDC Under Unbalanced Conditions

Cited by 74 publications

References 22 publications

Optimal Shaping of the MMC Circulating Currents for Preventing AC-Side Power Oscillations From Propagating Into HVdc Grids

Optimal Shaping of the MMC Circulating Currents for Preventing AC-Side Power Oscillations From Propagating Into HVdc Grids

Recent contributions and future prospects of the modular multilevel converters: A comprehensive review

Control of MMCs Under AC Grid Faults

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