Modified Phase-Locked Loop for Enhanced Synchronization in Single-Phase Grid-Connected PV Systems

J. Ali, A. S. Yaro, A. D. Usman, M. Ja'afar, G. A. Olarinoye, I. Abdulwahab, A. B. Kunya, S. Kunya, I. Seidu, Y. Alhassan

Abstract


Effective synchronization between grid-connected photovoltaic (PV) inverters and the utility grid is paramount for seamless energy injection, grid stability, and compliance with international standards. While conventional Phase-Locked Loops (PLLs) are fundamental for this purpose, they often struggle under non-ideal grid conditions such as voltage sags, harmonic distortion, and frequency deviations. This paper presents a comprehensive review of Modified PLL (MPLL) algorithms developed to address these limitations, proposing a novel taxonomy for their classification based on algorithm type, enhancement methodology, grid conditions addressed, and validation scope. Furthermore, the paper details the implementation of a specific MPLL algorithm that integrates adaptive filtering and fuzzy logic control to enhance synchronization performance under adverse grid conditions. Simulation results demonstrate the proposed MPLL's superior accuracy and response time during a 20% voltage sag, achieving a phase error within ±1∘ and a settling time of 80 ms, outperforming conventional PLLs. The paper also critically examines existing research gaps and challenges in MPLL development, including robustness against multiple concurrent disturbances, real-time implementation feasibility, scalability to weak grids and evolving standards, and limitations in validation methodologies. Finally, it outlines promising future directions leveraging artificial intelligence, the Internet of Things, and hybrid control techniques to pave the way for more intelligent and resilient synchronization solutions that support the reliable integration of PV systems into future smart grids.


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References


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