Phase-Locked Loop Using Complex-Coefficient Filters for Grid-Connected Inverter

Abstract

Recently, photovoltaic (PV) power systems have attracted considerable attention in an attempt to mitigate global warming. In a PV power system, it is necessary to synchronize the grid voltage when a PV inverter is interconnected with a grid. This paper proposes a high-speed and high-precision phase-locked loop (PLL) using complex-coefficient filters for a single-phase grid-connected inverter. The proposed PLL can detect the phase of grid voltage that has superimposed harmonic components for grid fault. Moreover, numerical results show the effectiveness of the proposed method.