A comparative analysis of p-PLL algorithms for single-phase utility connected systems

This work presents a comparative analysis between four algorithms used to implement single-phase Phase-Locked Loop (PLL) systems, which are based on three-phase instantaneous active power theory. PLL systems have been used in applications involving power conditioning equipments, for instance, series, parallel and hybrid active power filters, uninterruptible power supply (UPS) systems, controlled PWM rectifiers, and others. However, the information of the utility voltage, such as phase-angle, frequency or amplitude, need to be obtained with quality and precision to guarantee the good performance of the power conditioning equipments. As the single-phase PLL systems will be studied into two-phase stationary reference frame (alphabeta coordinates), a fictitious quadrature voltage must be obtained using appropriated strategies. Simulation and experimental results are presented in order to evaluate the performance of the single-phase PLL algorithms under distorted conditions of the utility voltage.