Handling of unbalanced faults in HVDC-connected wind power plants

Schönleber, Kevin; Prieto‐Araujo, Eduardo; Ratés-Palau, Sergi; Gomis‐Bellmunt, Oriol

doi:10.1016/j.epsr.2017.06.026

Cited by 9 publications

(6 citation statements)

References 29 publications

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“…Since the positive and negative sequence fault currents are required to be independently controlled with possibly different dynamic responses [16], the decoupled sequence control is applied to both the MMC and wind turbine VSCs. The phaselocked loop (PLL) is not required for the MMC since the angular frequency is directly set as the nominal frequency ω1 [17]. The double second-order generalized integrator (DSOGI)based PLL is utilized to extract the positive and negative sequence phase angles and magnitudes of the VSC terminal voltage, which are used to generate the fault current references according to the grid codes and the current limiter.…”

Section: System Descriptionmentioning

confidence: 99%

Coordinated Converter Control with Current Differential Protection under Unbalanced AC Fault in Offshore Wind Farm

Gao,

Blaabjerg,

Chen

et al. 2023

2023 IEEE 14th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)

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The modular multilevel converter (MMC) based high-voltage dc (HVDC)-connected offshore wind farm (OWF) is with converters on both sides of the offshore ac grid. After a shortcircuit fault on the offshore ac grid, the fault current from the MMC station can be controlled with a high flexibility to coordinate with the current differential protection. In this paper, the converter uncontrollability and overcurrent problems caused by the coordinated control during unbalanced faults are revealed. Thus, a coordinated fault control of the MMC suitable for the unbalanced fault is proposed to solve the uncontrollability problem. In addition, the proposed coordinated control is further modified to solve the MMC overcurrent problem. The simulation results indicate that the proposed coordinated control can ensure the operation of the current differential protection during unbalanced faults without the converter uncontrollability and overcurrent problems.

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Section: System Descriptionmentioning

confidence: 99%

Coordinated Converter Control with Current Differential Protection under Unbalanced AC Fault in Offshore Wind Farm

Gao,

Blaabjerg,

Chen

et al. 2023

2023 IEEE 14th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)

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“…The conforming discrete-time representations are deduced from the Forward Euler computation by replacing Equations ( 16), (18) and (19) in Equations ( 14) and ( 17) are denoted as follows:…”

Section: Mpdpc Based Cptmentioning

confidence: 99%

“…It is possible to directly obtain the unbiased voltage integrals by carrying out the mathematical functions in Equation (12). It is also possible to implement a bandpass filter (BPF), which functions as an ideal integrator, instead of the mathematical commands, because it also has the ability to remove the DC component of the grid voltages [18].…”

Section: Mpdpc Based Cptmentioning

confidence: 99%

“…It was found in the earlier studies, in terms of the unbalanced network conditions, that the typical solution in MPCC and MPDPC could determine the latest current or power references from the decomposition method for positive-and negative-sequence grid constituents [12,17]. The decomposition process essentially requires achieving the requirements of PLL, pulse-width modulation (PWM) or other complex extraction methods [18]. Sequence extraction methods [19] and PPL are not needed in [20,21]; however, it is essential to have power compensation strategy to accomplish sinusoidal current waveform, and simultaneously, there will be removal of the double grid frequency oscillations that is present in active as well as reactive powers.…”

Section: Introductionmentioning

confidence: 99%

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Predictive Direct Power Control for Dual-Active-Bridge Multilevel Inverter Based on Conservative Power Theory

et al. 2020

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This paper explores the feasibility of multilevel dual-active bridge-inverter (DABMI) applications for grid-connected applications of a modern Model of Predictive Direct Power Control (MPDPC) based on the conservative power theory (CPT). In the case of unbalanced grid voltages, the objective of the study is to promote continued active and reactive energy in MPDPC without reducing efficiency such as transient response and current harmonics. The nature of the instantaneous p-q theory permits only one out of three control targets to be fulfilled. The proposed control approached directly regulates the instantaneous active and reactive power to achieve three particular control objectives namely sinusoidal and symmetrical grid current, cancelling twice of fundamental grid frequency reactive power ripples, and removing twice grid frequency active power ripple. The techniques of complicated Grid part sequence extraction are unnecessary and improved at no extra expense, as is the case with current MPDPC fault-tolerant approaches. The instantaneous power at the next sampling instant is predicted with the newly developed discrete-time model. Each possible switching state will then be evaluated in the cost function defined until the optimal state which lead to the minimum power errors is determined. In MATLAB/Simulink simulation, the proposed CPT-based MPDPC measures reliability and performance at balanced and unbalanced grid voltages then compared with the conventional and existing MPDPC The proposed method manages to achieve all of three control targets which generates sinusoidal grid currents and attenuates active and reactive power ripple of twice the grid frequency exactly at the same time without losing its critical efficiency including transient reaction and current harmonics.

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“…However, once the unbalanced grid conditions occur (e.g., due to AC grid voltage unbalance and unsymmetrical faults), the converter will operate in abnormal condition and the negative sequence components in voltage and current will do great harm to system operation. If no compensation measures are adopted, the double frequency ripples will appear in the output power of VSC, which affects output quality of the converter [5][6][7] and may even make the converter malfunction. Therefore, how to suppress the double frequency ripples under unbalanced grid conditions becomes a hot topic in the research of VSC-HVDC control.…”

Section: Introductionmentioning

confidence: 99%

Active and Reactive Power Compensation Control Strategy for VSC-HVDC Systems under Unbalanced Grid Conditions

Liu

Zhai

et al. 2018

Energies

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This paper presents a power compensation strategy to suppress the double frequency power ripples of Voltage source converter high-voltage direct current (VSC-HVDC) systems under unbalanced grid voltage conditions. The mathematical control equations of the double frequency ripple power of VSC under unbalanced operating conditions are firstly derived and established, where the dynamic behaviors of the double frequency ripples in active and reactive power are regarded as being driven by current-relevant components and voltage-relevant components, respectively. Based on the equations, a power compensation control strategy of VSC-HVDC is proposed via the passivity-based control with disturbance observer to suppress both the current-relevant and voltage-relevant components in the power ripples. With this control strategy, the double frequency ripples in active and reactive power are suppressed simultaneously and system performance is significantly enhanced with the implementation of the disturbance observer in the passivity-based control. Theoretical stability analysis and simulation cases show the effectiveness and superiority of the proposed strategy.

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Handling of unbalanced faults in HVDC-connected wind power plants

Cited by 9 publications

References 29 publications

Coordinated Converter Control with Current Differential Protection under Unbalanced AC Fault in Offshore Wind Farm

Coordinated Converter Control with Current Differential Protection under Unbalanced AC Fault in Offshore Wind Farm

Predictive Direct Power Control for Dual-Active-Bridge Multilevel Inverter Based on Conservative Power Theory

Active and Reactive Power Compensation Control Strategy for VSC-HVDC Systems under Unbalanced Grid Conditions

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