PLL and Self-synchronized Synchonverter: An Overview of Grid-inverter Synchronization Techniques

In this paper, a brief summary of synchronization approaches is discussed sequentially from older techniques to latest technology. There are many techniques that have been developed which focusing of synchronization, from basic grid evaluating technique, phase-locked-loop (PLL) and later to synchronous reference-frame phase-locked-loop where is established on basis of phase estimation and determination where it can give fast synchronization time. Recently, due to the advancement of inverter control strategy which is based on the mathematical formulas derivation, a synchronous generator characteristic can be integrated in the inverter controller design. As a result, the inverter will behave like the synchronous generator whereas known it has fast synchronization time and known as synchronverter. At the end of this paper, a comparison table among the existing PLLs with synchronverter in terms of efficiency will be addressed.