A PLL-Less Fourier Analysis Based Self-Synchronizer for Synchronverter having Uninterrupted Power Supply Capability

Abstract

With the passage of time, more and more power electronic converters are being integrated in power system. This growing pattern of inertia-less inverters challenges the system frequency and voltage. Synchronverter, that mimics real synchronous generator, is a promising solution of frequency and voltage stability in future power grid. It has inherent capability to remain synchronized with the grid. However, it requires phase tracking of the grid voltage prior to grid connection. Several PLL-less self-synchronization approaches for synchronverter have been proposed by researchers. Existing PLL-less approaches either lack uninterrupted power supply capability during synchronization process or have unwanted delays and uncertainties depending upon certain grid conditions. In this paper, a Fourier Analysis based synchronizer for synchronverter is proposed that (a) ensures uninterrupted power supply capability during synchronization, and (b) presents a fast, and reliable solution of synchronization independent of phase and magnitude differences between the synchronverter and grid voltages. The proposed synchronizer is designed, validated by simulations, and compared with the existing Differential Root Mean Square Voltage (DRMSV-) based approach. Results have shown that the proposed synchronizer has improved the speed and certainty of synchronverter self-synchronization under adverse grid conditions.