Experimental Validation of a Combined Multi-Variable Filter – Dual Second Order Generalized Integrator Phase-Locked Loop Technique

Abstract

Nowadays, renewable energy sources are being extensively used. They are connected to the grid via power converters that require the knowledge of the grid voltage magnitude and phase in order to operate correctly. The values of the grid phase and voltage are usually calculated using Phase Locked Loop (PLL) techniques. However, the grid voltage may be distorted due to non-linear loads and urban expansion thus the need of a PLL robust toward voltage distortions. The conventional PLL technique does not present accurate results in front of these distortions thus the necessity of a technique able to cope with different grid faults. This paper presents the design and the dynamic behavior of a PLL method (MVF-DSOGIPLL) combining two main filters: the Multi Variable Filter (MVF) and the Dual SOGI-based quadrature signal generator (DSOGI-QSG) along with the conventional Synchronous Reference Frame PLL (SRF-PLL). This PLL is implemented on FPGA to verify the analytical results. Simulation and experimental results validate the efficiency of the proposed technique.