Electronic Science and Technology ›› 2022, Vol. 35 ›› Issue (4): 78-86.doi: 10.16180/j.cnki.issn1007-7820.2022.04.013

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Characteristic Signal Extraction of Non-Ideal Three-Phase Grid

Qingqing YUAN,Min JIANG,Yumei YANG   

  1. School of Mechanical Engineering,Shanghai University of Science and Technology,Shanghai 200093,China
  • Received:2020-11-17 Online:2022-04-15 Published:2022-04-15
  • Supported by:
    National Key R&D Program(2018YFB0104603);Shanghai Youth Science and Technology Talents Sailing Program(18YF1418300)


When the three-phase grid voltage is distorted or unbalanced, there are many non-ideal characteristic signals in the grid-connected system, such as harmonics and negative sequence components. In view of such problems, this study proposes a harmonic and negative sequence component extraction algorithm based on ISDFT. This algorithm redesigns the transfer function of the SDFT, which retains good signal filtering characteristics while improving the response rate of the system, and has strong flexibility. Experimental results show that ISDFT can quickly and accurately extract characteristic harmonics and negative sequence components, and ISDFT has good dynamic stability when the load changes suddenly. In addition, in terms of the extraction results of the 5th and 7th harmonics, DFT, SDFT, and ISDFT have the same effect of extracting harmonics, but the response rate of ISDFT is 44.56% faster than SDFT and 65.32% faster than DFT.

Key words: non-ideal grid, grid voltage distortion, grid voltage imbalance, improved sliding discrete Fourier transform, harmonic extraction, negative sequence component, positive and negative sequence separation, power quality

CLC Number: 

  • TN710.1