Accurate estimation of single-phase grid voltage parameters under distorted conditions

Md. Shamim Reza, Mihai Ciobotaru, Vassilios G. Agelidis

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)


This paper presents an accurate technique for the estimation of single-phase grid voltage fundamental amplitude and frequency. The technique consists of a quadrature signal generator (QSG) and a discrete Fourier transform (DFT). The frequency information required by the QSG based on a second-order generalized integrator (SOGI) is estimated using the spectral leakage property of the DFT. The presented DFT operation does not require real-time evaluation of trigonometric functions. The frequency estimation is less affected by the presence of harmonics when compared to similar techniques based on QSG-SOGI such as the phase-locked loop and the frequency-locked loop. Moreover, unlike these techniques, the DFT-based QSG-SOGI (DFT-SOGI) technique does not create any interdependent loops, thus increasing the overall stability and easing the tuning process. The effectiveness of the proposed technique has been validated on a real-time experimental setup.
Original languageEnglish
Pages (from-to)1138-1146
Number of pages9
JournalIEEE Transactions on Power Delivery
Issue number3
Publication statusPublished - Jun 2014
Externally publishedYes


  • Discrete Fourier transform (DFT)
  • grid voltage monitoring
  • parameter estimation
  • phase-locked loop (PLL)
  • quadrature signal generator (QSG)
  • second-order generalized integrator (SOGI)
  • single-phase system


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