SOGI-FLL for synchronization and fault detection in an inverter connected to the grid

This paper presents a theoretical analysis and simulation for the design and implementation of a Second Order Generalized Integrator - Frequency Locked Loop (SOGI-FLL) aimed at synchronization and fault detection when connecting an inverter to the utility grid. Such an inverter is implemented in a Highly-Efficient-and-Reliable- Inverter-Concept (HERIC) topology. The two main aims of this work are: First, the frequency and phase synchronization of the HERIC power inverter with the grid through the SOGI-FLL. Second, the detection of abnormal conditions that may occur in the coupling point system by analyzing changes in frequency, phase shifts and amplitude variations. This is done by complying with the IEEE 1547 standard for disconnecting generation systems to the grid in case of failure. Finally, from the experimental results, it can be concluded that the SOGI-FLL system is an appropriate alternative for controlling the injection of energy process into the grid, as well as for detecting possible grid faults.