Sequence Control Strategy for Grid-Forming Voltage Source Converters Based on the Virtual-Flux Orientation under Balanced and Unbalanced Faults

Fernández, Juan Dolado; Carrasco, J. Eloy-Garcia; Arnaltes, Santiago; Rodriguez-Amenedo, José Luis

doi:10.3390/en16073056

Cited by 4 publications

(2 citation statements)

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“…To achieve this goal, the first step is to consider the voltage positive sequence because it obtaining a balanced three-phase signal in phase with the original unbalance grid voltage signal. The positive sequence [ 21 , 22 ] can be obtained as:

where

is the grid voltage phasor, and

is the grid voltage’s positive sequence.

represents a 120° phase shift; therefore, the following identity can be employed to be able to apply ( 38 ) in the time domain:

where

represents the phase shift, which represents 120° or −120° for

and

, respectively.…”

Section: Power Converter Resonant Controlmentioning

confidence: 99%

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Power Converter Resonant Control for an Unbalanced and Non-Constant Frequency Supply

Rohten

Villarroel

Silva

et al. 2023

Sensors

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Distorted voltage supplied as unbalanced and/or non-constant frequency can be found in weak grids, such as microgrids, or systems working in islanding mode. These kinds of systems are more sensitive under load changes. Particularly, an unbalanced voltage supply may be produced for large, single-phase loads. On the other hand, the connection/disconnection of high current loads may lead to important frequency variation, especially in weak grids where the short circuit current capacity is reduced. These conditions make the control of the power converter a more difficult task, because of the variations in the frequency and unbalancing. To address these issues, this paper proposes a resonant control algorithm to deal with variations in the voltage amplitude as well as grid frequency when a distorted power supply is considered. The frequency variation is an important drawback for resonant control because the resonance must be tuned at the grid frequency. This issue is overcome by using a variable sampling frequency in order to avoid re-tuning the controller parameters. On the other hand, under unbalanced conditions, the proposed method relaxes the phase with lower voltage amplitude by taking more power from the other phases in order to help the stability of the grid supply. To corroborate the mathematical analysis and the proposed control, a stability study is performed, including experimental and simulated results.

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where

is the grid voltage phasor, and

is the grid voltage’s positive sequence.

represents a 120° phase shift; therefore, the following identity can be employed to be able to apply ( 38 ) in the time domain:

where

represents the phase shift, which represents 120° or −120° for

and

, respectively.…”

Section: Power Converter Resonant Controlmentioning

confidence: 99%

Section: Phase Locked Loop (Pll) For Unbalanced Grid Conditionmentioning