Transient Stability Improvement by Plugging Mode Operation of Grid Connected Squirrel Cage Induction Generators

Recently a new and simple method to mitigate the transient instability of squirrel cage induction generators (IG) without using any additional equipment. The majority of the fixed speed wind turbines are equipped with squirrel cage IG and ac connected to the power system. During a fault in power system, voltage and rotor speed instability may occur, especially when the strength of the system compared to the power delivered by the IG is relatively low. For stability improvement, the possibility of altering the operating mode of the induction machine from the generating to the plugging mode for a short time. A simulated model of the system is developed with MATLAB and the system studies of induction machine are carried out with this model.Simulation results show that the proposed method can be effective in enhancing the transient stability. The speed, electric torque, stator and rotor current plots are obtained. Index Terms Induction generators (IGs), plugging mode, squirrel-cage, transient stability.