Interaction of the dynamics of doubly fed wind generators with power system electromechanical oscillations

The interaction of the dynamics of doubly fed wind generators with the electromechanical mode of nearby synchronous generators (SGs) can affect the small signal stability of power systems with high penetration levels of wind power. In this study, a novel approach is developed to investigate these interactions and their impact on the damping of power system oscillations. In this approach it is not necessary to model the dynamic behaviour of system SGs and only the frequencies of system oscillations are important. This approach is based on the sensitivity of SGs electromechanical eigenvalue with respect to variations in the Jacobian matrix of power system. By applying this approach to a test system, two of the wind farm (WF) modes are identified to have interaction with the SG electromechanical mode, one has detrimental and the other has beneficial impact, which decrease the damping of system electromechanical oscillation altogether. By using the modal analysis technique, the WF controller gains are retuned to shift the detrimental and beneficial interacting modes away and towards the frequency of system oscillation, respectively. It is shown that this results in the improvement of system oscillation damping whereas the dynamic performance of WF remains satisfactory.