Assessment of the Best Integration of DFIG-based Wind Turbine with Reference to Power System Stability

Even though DFIGs are among the most promising wind turbines, they have negative effects on system performance, particularly system stability when connected to a grid. This paper proposes a reliable algorithm that measures the impact of integrating Doubly Fed Induction Generators (DFIGs) wind turbines on the power system stability. This proposed algorithm can be used to determine the optimal location, size, and operation of DFIGs into the original system. The algorithm can also be utilized to achieve the proper system operation without any violation of stability limits: small-signal, voltage, frequency, and transient stability. The effect of wind speed variations and load rejection on frequency stability is used to ensure the power system is safely operated within the acceptable frequency limits and to determine the primary frequency response for each case. Finally, the influence of DFIGs on transient stability using TSI (Transient Stability Index) and the changes in CCT (Critical Clearing Time) of critical transmission lines after replacing synchronous generators with DFIGs are calculated. Without exceeding the voltage stability constraints, a penetration level of 21% is the highest that can be used. The speed control becomes difficult at penetration levels of 31% and 41% since a frequency response should be less than 9 seconds. The algorithm is applied to the IEEE 39-bus system using DIgSILENT software.