Assessing the critical compensation level associated to subsynchronous oscillations in DFIG wind power systems

Abstract

This paper develops an algorithm to determine the critical (minimum) compensation level above which a DFIG-based wind power system can become unstable due to a subsynchronous resonance, depending on the specific combination of the number of in-service wind turbines. The algorithm employs a numerical continuation process that varies the compensation level and the in-service wind turbines. It begins at a point of the stability boundary hypersurface, where the subsynchronous mode has zero real part, and performs concatenated two-parameter numerical continuations of this condition until the global minimum compensation level is reached. The methodology is explained on a simple radial power system and then it is tested using a practical system.