Open AccessEffect of adding DC‐offset estimation integrators in there‐phase enhanced phase‐locked loop on dynamic performance and alternative scheme
Author(s) -
Wu Fengjiang,
Zhang Lujie,
Duan Jiandong
Publication year - 2015
Publication title -
iet power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 77
eISSN - 1755-4543
pISSN - 1755-4535
DOI - 10.1049/iet-pel.2014.0317
Subject(s) - control theory (sociology) , integrator , offset (computer science) , phase locked loop , loop (graph theory) , dc bias , phase (matter) , three phase , computer science , mathematics , engineering , physics , telecommunications , voltage , electrical engineering , artificial intelligence , control (management) , bandwidth (computing) , quantum mechanics , programming language , combinatorics
Three‐phase enhanced phase‐locked loop (3P‐EPLL) can estimate the amplitude, frequency and phase angle of the positive sequence of the three‐phase inputs without using a synchronous reference frame. However, the presence of DC offsets in the inputs of the conventional 3P‐EPLL introduces a periodic ripple in the estimated information. Thus, DC‐offset estimation integrators (DCEIs) to estimate and feedback the DC component as an error signal are introduced in 3P‐EPLL to eliminate the disturbance. This study presents a comprehensive study of the transient performance of 3P‐EPLL with DCEIs, proving that a worse and longer dynamic period is caused by the coupling of the frequency and amplitude loop resulted from DCEI. Further, a hybrid filtering 3P‐EPLL based on delayed‐signal cancellation to reject the DC component and sliding Goertzel transform‐based filter to eliminate the effect of harmonics and unbalanced inputs is proposed. Thus, a correct estimation is achieved even under unbalanced inputs with both DC and harmonic components. A set of detailed experiments of the former three enhanced phase‐locked loops (EPLLs) are presented to display the deficit of the conventional EPLLs and better performance of the proposed scheme.