A Current Phase Controlled Sub-Synchronous Damper Converter for Liquefied Natural Gas Plants Applications

In Liquefied Natural Gas (LNG) plants Sub-Synchronous Torsional Interactions (SSTI) phenomena can imply torsional instability. The Sub-Synchronous Damper (SSD) converter provides solution to the SSTI phenomena. In this paper a current phase control system is proposed for the SSD converter. The phase of the SSD current reference is calculated starting from the measurement of the Turbine-Generator current oscillations and of the Turbine-Generator speed oscillations. Correct operation of SSD converter and successful torque oscillation reduction are verified.