Publication

Abstract : The wind farms are established at distant places from the grid system, hence the series capacitive compensated long transmission lines are used in grid tied system. However, the insertion of series capacitors leads to electromagnetic torque oscillations between the turbine and generator shafts which can cause shaft fatigue. This phenomenon is well known as Sub Synchronous Resonance (SSR) oscillations. This paper investigates the effect of varying the capacitive compensation level on the performance of Squirrel Cage Induction Generator (SCIG) through the small signal modelling. The small signal model of the complete system comprising of the wind turbine, SCIG and series compensated grid connected transmission line is proposed for the analysis of SSR using their state space equations. The small signal analysis of SSR is examined by three approaches such as Eigen value approach, simulation analysis and importantly experimental approach for varying capacitive compensation levels. To verify the simulationbased analysis, the laboratory setup is developed on 2.2kW SCIG integrated into the grid through the scaled down model of series compensated transmission line. From the simulation and experimental results, it has been observed that the addition of capacitive compensation level increases the power transfer capacity. However, the addition of percentage compensation increases beyond 50% lead to electromagnetic torques oscillations between turbine and shaft.