Analysis and implementation of a PLL structure for single-phase grid-connected inverter system

This paper presents the analysis and implementation of a PLL structure for single-phase grid-connected system. By comparing two different PLL structures based on SRF (synchronous reference frame) and p-q (instantaneous reactive power) theory respectively, a simplified control model of the PLL system is developed. This paper also analyzes the generation of the orthogonal voltage system based on SOGI which is essential in both of the PLL structures. Finally, simulation based on MATLAB and experimental results from a DSP-based system are all included to support the theoretical analysis.