Review on Three-Phase PLLs for Grid Integration of Renewable Energy Sources

The developments in the field of Renewable Energy Sources (RES) and a rising environmental concern over the use of conventional sources of energy clubbed together have led to the advent of the distributed sources of energy in the Power Generation and Distribution Systems. Such an integration need to be coherent. RES should ride through any grid disturbances successfully and work in synchronism with the utility grid. This requires the phase angle information apart from the utility voltage magnitude. Phase locked loops (PLLs) is such a technique for estimating the synchronisation information. Various developments have happened in the PLL schemes since it was first used for grid-tie applications. This paper aims to provide a comprehensive review on the use of three-phase PLLs for grid synchronization purposes. A test system based review of the various PLL schemes is done for working under various utility grid conditions. The paper also provides a comparison between different PLLs which can be very helpful as a reference for engineers, and can provide useful insights to academic researchers.