Analysis of single-phase PLL with novel two-phase generator for grid-connected converters

It is very important for proper work of grid-connected converters to have accurate detection of phase angle, frequency and amplitude of grid voltage. Estimation of these grid parameters can be achieved using PLL (phase locked loop) based on SRF (synchronous reference frame) theory. This PLL should have robustness against noise and offset introduced by measurement and data conversion. This paper proposes an improved PLL algorithm that has excellent noise and offset rejection property. The main part of the proposed PLL is a novel two-phase generator which is used to obtain two quadrature signals for SRF block and PI regulator in closed control loop.