A vector control strategy to eliminate active power oscillations in four-leg grid-connected converters under unbalanced voltages
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Mora Castro, Andrés Felipe
Cárdenas Dobson, Jesús Roberto Pedro Alejandro
Urrutia O., Matías
Espinoza Bolaños, Mauricio
Díaz Díaz, Matías
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Abstract
The problems associated with active power oscillations (APOs) in grid-connected converters are well-known. Imbalances in the grid usually produce double-frequency oscillations in the dc-link voltage and current which could reduce the useful life of solar panels, batteries, and capacitors connected to this point. Moreover, as reported in the literature, double-frequency
reactive power oscillations (RPOs) also produce adverse effects
in distribution systems, and it is desirable to eliminate or
mitigate them. When a four-leg power converter is connected
to an unbalanced grid, the zero-sequence current provides
extra degrees of freedom to compensate or even eliminate the
power oscillations at the converter dc-link side. In this paper,
a new methodology to regulate these double-frequency power
components is proposed. It is based on a closed-loop vector
control approach, where the active power oscillations (APOs)
at converter side are transformed into a synchronous frame
rotating at twice the grid frequency and regulated using the
zero-sequence current. To avoid overcurrent produced by the
circulation of positive-, negative-, and zero-sequence components a current limiter is also proposed in this paper. Experimental results obtained with a 4-kW four-leg power converter prototype are presented and discussed in this paper.
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Keywords
DC–AC converters, distribution system, symmetrical components, Reactive power, DC-AC power converters, Power distribution, Power control
Citation
https://ieeexplore.ieee.org/abstract/document/8732350