Calculation of Stable Domain of DFIG-Based Wind Farm in Series Compensated Power Systems

Subsynchronous oscillation (SSO) has concerned scholars who work with doubly-fed induction generator (DFIG)-based wind farms which are interfaced with series compensated power systems. The critical factors impacting SSO are compensation level K
_C
, proportional gain of rotor side controller (RSC) current tracking control K
_P3
, number of DFIGs, and wind speed. In this paper, we analyze the stable domain of K
_C
and K
_P3
as it is impacted by variable and uncontrollable wind speeds. Eigenvalues are used to conduct comprehensive stability analyses of the power systems, in which participation factors are employed to identify oscillation modes, and the trajectories of all the oscillation modes versus K
_C
and K
_P3
are presented to support the identification results, time domain simulation based on Simulink is also applied to verify the conclusions. Monte Carlo simulation is conducted to simulate the variable characteristic of wind speed by sampling the Weibull distribution. The impacts of the number of DFIGs and transmission distance on the stable domain are analyzed, the stable and SSO probabilities are employed in the stable domain under a variable wind speed. The constant stable domain of K
_C
and K
_P3
is presented, the power system will remain stable under a variable wind speed in this area.