Dynamics Assessment of Advanced Single-Phase PLL Structures

Recently, several advanced phase locked loop (PLL) techniques have been proposed for single-phase applications. Among these, the Park-PLL, and the second order generalized integrator (SOGI) based PLL are very attractive, owing to their simple digital implementation, low computational burden, and desired performance under frequency-varying and harmonically distorted grid conditions. Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet. Through a detailed mathematical analysis it is shown that these two PLL structures are equivalent to each other, from the control point of view. Then, a linearized model is developed which is valid for both PLLs. The derived model significantly simplifies the stability analysis and the parameter design. To fine-tune the PLL parameters, a systematic design approach is suggested afterwards, which guarantees a fast dynamic response, a high disturbance rejection ability, and a robust performance. Finally, the simulation and experimental results are presented to support the theoretical analysis.