Grid Fault Resilient Hybrid Grid Synchronization for Single-Phase Solar Inverter

Cameron Jones, Animesh Sahoo, Jayashri Ravishankar, Iraklis Nikolakakos, Tareg Ghaoud

Abstract: Prolonged resynchronization times resulting in inaccurate voltage parameter estimations during post grid fault recovery are the major causes of poor ride-through of inverters. Thus, a fault resilient hybrid grid synchronization technique is proposed in this paper. It consists of a second-order generalized integrator phase-locked loop (SOGI-PLL) that provides noise-robust voltage estimates under nominal grid conditions. During faults, it uses an open-loop technique, based on a recursive discrete Fourier transform (RDFT) pre-filter and delayed signal frequency estimate, and arctan phase-angle estimate. A rate-of-change-of-frequency (ROCOF) and rate-of-change-of-voltage (ROCOV) monitoring system is designed to detect fault conditions and facilitate smooth output switching between the PLL and the open-loop estimates. It avoids the PLL delay and provides faster estimates during grid faults. The proposed technique is tested against phase-angle jumps, frequency variations, and voltage sags, showing improved resynchronization times of 50ms, and comparable transient errors and harmonic rejection capabilities to standard SOGIPLL.

External IDs:dblp:conf/isie/JonesSRNG22