Frequency Estimation Improvement for Single-Phase Phase-Locked Loop Using Digital RST controller

Vongkoon, Pokkrong; Liutanakul, Pisit

doi:10.1109/gtdasia.2019.8715963

Cited by 4 publications

(3 citation statements)

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“…These ac components in (11) are also represented as phasors to simplify the analysis. This can be accomplished by multiplying each error signal component of (9) and (10) by the gain and phase of the PI controller at specific frequencies ((34)- (37) in the Appendix). Thus, each of the ac components in (11) can be derived as follows:…”

Section: Influence Of Power Decoupling Capacitances On Dc-link Ripplementioning

confidence: 99%

“…To generate a reference grid current, the RMS value of the reference grid current in (14) is multiplied by a template sinusoidal waveform from the traditional single-phase phase-locked loopbased inverse Park transformation with the PI controller detailed in [37], resulting in…”

Section: Influence Of Power Decoupling Capacitances On Dc-link Ripplementioning

confidence: 99%

“…Thus, each of the ac components in (11) can be derived as follows:

{\tilde{p}}_{ω}^{ref} = {\tilde{V}}_{E, ω} false(K_{ω} ∠ θ_{ω} false) = \frac{B {\overset{false^}{I}}_{normalg} K_{ω}}{ω_{normalg}} ∠ (90 ° + θ_{ω})

{\tilde{p}}_{2 ω}^{ref} = {\tilde{V}}_{E, 2 ω} false(K_{2 ω} ∠ θ_{2 ω} false) = - A K_{2 ω} ∠ θ_{2 ω}

Then, the reference power generated by a classical PI controller is divided by the root‐mean‐square (RMS) value of the grid voltage. The RMS value of the reference grid current can be expressed as

\begin{matrix} right leftthickmathspace.5em \\ i_{rms}^{ref} (t) & = \frac{P^{ref}}{V_{rms}} + \frac{B {\overset{false^}{I}}_{normalg} K_{ω}}{ω_{normalg} V_{rms}} \sin (ω_{g} t + 90 ° + θ_{ω}) \\ - \frac{A K_{2 ω}}{V_{rms}} \sin false(2 ω_{normalg} t + θ_{2 ω} false) \end{matrix}

To generate a reference grid current, the RMS value of the reference grid current in (14) is multiplied by a template sinusoidal waveform from the traditional single‐phase phase‐locked loop‐based inverse Park transformation with the PI controller detailed in […”

Section: Harmonic Currents Of Dshbmmentioning

confidence: 99%

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Effective low‐cost solution using cascaded connection of two modified notch filters to mitigate the second and third harmonic currents in single‐phase dual‐stage half‐bridge microinverter

Vongkoon

Liutanakul

Wiwatcharagoses

2019

IET Power Electronics

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On the grid side, the half-bridge topology of the microinverter is of interest for solar rooftop applications because of its high efficiency, low component count, and cost-effectiveness. However, it has an inherent double-line frequency ripple voltage on the dc-link, which causes the injection of a third-order harmonic current when the voltage control loop is closed. Furthermore, in practice, different average voltages or different capacitances of the two capacitors at the dc-link produce a second-order harmonic current that flows into the grid. In this paper, the analytical details of these harmonics are comprehensively described, and a simple and effective low-cost technique using the cascaded connection of two modified notch filters is proposed in the voltage control loop to mitigate their effects. The simulation and experimental results of a 300 W microinverter indicate that the proposed filters represent an effective low-cost solution and perform well in accordance with the IEEE 1547 standard, even if the capacitances at the dc-link are mismatched by 20%. Besides, the prototype is tested when occurring of the changing +1% of the line frequency, or appearing of the distorted waveform of grid voltage with the composition of 6% of fifth-order harmonic. Nomenclature Capital boldface italic letters such as V, represent phasors. Capital italic letters such as C 1 , represent constant variables. Small italic letters such as v dc (t), represent instantaneous variables depending on time. Small italic letters such as ṽ dc (t), represent small ac signals in the time domain. Capital italic letters such as G vp (s), represent transfer functions in the s-domain. Small italic letters such as v dc (s), represent signal variables in the s-domain.

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Section: Influence Of Power Decoupling Capacitances On Dc-link Ripplementioning

confidence: 99%

Section: Influence Of Power Decoupling Capacitances On Dc-link Ripplementioning

confidence: 99%

“…Thus, each of the ac components in (11) can be derived as follows: