Damping tie line oscillation using permanent magnet wind generators in the Libyan power system

In this paper we consider the Libyan power system and its two interconnected areas. The interest in this system is because one of its power areas is expected, in the near future, to host a significant quantity of wind turbines to bolster the local conventional generation. A dynamic model is presented in the paper for the two-area system including a detailed aggregate model of the wind generation system and its controls. Simulation results presented in the paper show that certain disturbances including wind velocity changes can potentially give rise to undamped tie line power oscillations. Subsequently, a control method is proposed to deal with these oscillations by utilizing the fast power modulation capabilities of the wind generator dc link. The proposed method uses the energy stored in the dc link capacitors rather than modifying the power output of the wind turbine. Therefore, secondary torsional oscillations introduced from the wind turbine and potential instability can be avoided. Simulation results using the proposed method show that adequate and effective damping is possible without perturbing the operation of the wind turbine.