PROJECT TITLE:

Impedance-Based Analysis of Grid-Synchronization Stability for Three-Phase Paralleled Converters - 2015

ABSTRACT:

Grid synchronization stability issues and subsynchronous oscillations between synchronous generators exist in electrical power systems. Three-part voltage-source converters (VSCs) are being put in additional and more within the grid to improve efficiency or to utilize renewable energy sources. The identical stability issues between VSCs are also reported and analyzed employing a little-signal model of section-locked loops (PLLs). This paper proposes a different impedance-primarily based analysis technique. The proposed method shows that synchronization instability in a VSC system is because of the negative incremental resistance behavior of grid-tied inverters' impedance when they are modeled in the d-q frame. System can be stabilized simply by changing the inverter's PLL style. Experimental results verify the analysis and the proposed method.