Evaluation of different positive sequence detection structures applied to grid-connected systems

Effects of three different positive sequence detector structures including qPLL, EPLL, and SOGI-PLL on performance of a 10KVA shunt active filter are investigated in this paper. The evaluation is performed through simulation of practical test conditions including balanced and unbalanced grid voltage, frequency variation, and harmonic polluted grid voltage. These studies lead to recognizing the SOGI-PLL as a proper method for grid-connected power applications, especially for the ones with digital control systems.