Design of an advanced PLL for accurate phase angle extraction under grid voltage HIHs and DC offset. Issue 6 (26th April 2018)

• Record Type: Journal Article
• Authors: Ali, Zunaib; Christofides, Nicholas; Hadjidemetriou, Lenos; Kyriakides, Elias
• Is Part Of: IET power electronics. Volume 11:Issue 6(2018)
• Page Start: 995
• Page End: 1008
• Publication Date: 2018-04-26
• Subjects: power system harmonics -- phase locked loops -- power system dynamic stability -- dynamic response -- computational complexity; advanced PLL -- phase angle extraction -- grid voltage HIHDO -- direct current offset -- harmonics‐interharmonics -- grid voltage input signal -- phase‐locked loop -- controller response -- high‐frequency oscillations -- low‐frequency oscillations -- PLL estimated phase -- HIH rejection capability -- international standards -- grid‐tied converters -- fundamental frequency oscillations -- input signal -- dynamic response -- low‐pass filters -- mathematic‐cancellation decoupling cell -- harmonic compensation network -- HCN module -- computational complexity -- synchronisation; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2017.0424
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : The presence of direct current (DC) offset and harmonics–interharmonics (HIHs) in grid voltage input signal of phase‐locked loop (PLL) results in inaccurate controller response. The inaccuracies are due to the low‐ and high‐frequency oscillations that appear in the PLL estimated phase, amplitude and frequency. The suppression of fundamental frequency oscillations caused by DC offset (DO) in the input voltage signal must be carried out without compromising the dynamic response of the system. The use of low‐pass filters, for example, results in undesirable, slow response. This study proposes an accurate and fast decoupling of fundamental frequency oscillations using a mathematic‐cancellation decoupling cell. Higher‐frequency oscillations generated by HIHs are eliminated by a different harmonic compensation network (HCN) that is also proposed in this study. The performance of conventional techniques is limited because they eliminate only specifically selected harmonics. The proposed PLL, however, eliminates any number of HIHs present in the grid with the least computational complexity and without any prior knowledge. Furthermore, its advanced features provide accurate synchronisation under any abnormal grid condition at the lowest computational complexity when compared with the existing state‐of‐the‐art PLLs. The advanced performance of the proposed HIHDO‐PLL is verified through simulation and experimental results.