Enhanced PLL for Three-Phase Single-Stage Multifunctional Grid-Connected SPV System.

The paper presents a multifunctional inverter for a three-phase single-stage gridconnected Solar Photo-Voltaic System (SPV) system with Enhanced Phase Locked Loop (EPLL)-based control algorithm. The EPLL-based Quadrature Signal Generation (QSG) estimates the magnitude of source voltage and load current signal and Phase-Locked Loop (PLL) estimates phase angle of the grid voltage. This estimation is used to design a proper controlled algorithm which improves the power quality such as reactive power compensation, harmonic rejection and DC offset rejection, in addition to feeding the SPV energy to load and grid. Perturb and Observe (P&O)-based Maximum Power Point Tracking (MPPT) is used to estimate the reference PV voltage signal and power. The EPLL-based controller tracks the signal even under distorted grid supply conditions such as voltage sag/swell and harmonics to improve the dynamic response. These multifunctional capabilities of the inverter make the system more efficient for feeding the SPV energy to grid. Various operating conditions are shown to validate the proposed controlled algorithm using MATLAB/Simulink. [ABSTRACT FROM AUTHOR]