Grid-interactive power converters are normally synchronized to the grid using
phase-locked loops (PLLs). The performance of the PLLs is affected by the
non-ideal conditions in the sensed grid voltage such as harmonics, frequency
deviations and dc offsets in single-phase systems. In this paper, a
single-phase PLL is presented to mitigate the effects of these non-idealities.
This PLL is based on the popular second order generalized integrator (SOGI)
structure. The SOGI structure is modified to eliminate of the effects of input
dc offsets. The resulting SOGI structure has a high-pass filtering property.
Hence, this PLL is termed as high-pass generalized integrator based PLL
(HGI-PLL). It has fixed parameters which reduces the implementation complexity
and aids in the implementation in low-end digital controllers. The HGI-PLL is
shown to have least resource utilization among the SOGI based PLLs with dc
cancelling capability. Systematic design methods are evolved leading to the
design that limits the unit vector THD to within 1% for given non-ideal input
conditions in terms of frequency deviation and harmonic distortion. The
proposed designs achieve the fastest transient response. The performance of
this PLL has been verified experimentally. The results are found to agree with
the theoretical prediction.Comment: 22 pages, 13 figures and 2 table
