A Control for Preventing False Tripping of Grid-Tied Renewable Systems With Increased Solar Penetration and Fluctuating Load Demand

High penetration of solar energy systems leads to power variability at point of common coupling (PCC). This accompanied with high demand fluctuations, reflects as highly fluctuating effective loading at PCC. This leads to fictitious jump in estimated frequency by phase/frequency locked loops (PLLs/FLLs) due to associated voltage phase angle jumps at PCC during such power variability. This fictitious frequency jump translates into triggering synchronization control leading to false tripping of power electronic switch isolating system from grid. This is more dominant in highly variable renewable dominated sources such as solar power generating systems (SPGS). This work presents a control to prevent occurrence of fictitious jumps in estimated frequency by incorporating an approach to decouple amplitude and phase/frequency estimation loops, and providing additional immunity to frequency loop against any phase transients. Additionally, a blinder arrangement is proposed to minimize trip attempts to ensure steady state phase/amplitude matching during synchronization. Proposed methodology improves system operation and reliability. It also improves power quality performance during supply voltage and load current distortions. Simulation and experimental results are provided to validate performance with presented methodology.