Implementation of Phasor Measurement Unit Based on Phase-Locked Loop Techniques: A Comprehensive Review

The dynamic monitoring, control, and protection of modern power systems in real time require time-stamped electrical measurements to accurately estimate the bus voltage phasors using state estimation function under normal abnormal conditions. These can be acquired by time-synchronized devices, known as phasor measurement units (PMUs). PMUs measure branch current a three-phase network, well frequency rate change (ROCOF), with high speed, accuracy stamping provided global positioning system (GPS) at coordinated universal (UTC). Various algorithms have been proposed literature, while most them are concentrated discrete Fourier transform (DFT) algorithm, where an integer number samples multiple nominal is required for computations. In cases grid deviates from its value, raw application DFT approach lead large errors during estimation. Another based on phase-locked loop (PLL) techniques, widely used tie inverters. PLL techniques track dynamically (continuous time) estimated time-variant grid. A brief introduction basic concepts synchrophasor definition provided, main methods according recent literature mentioned. PLL-based PMU reviewed both steady-state conditions IEEE standards. conclusion, performance presented this review discussed.