Reactance Scan Crossover-Based Approach for Investigating SSCI Concerns for DFIG-Based Wind Turbines

This paper presents a reactance crossover-based technique to investigate subsynchronous control interaction (SSCI) concerns associated with doubly fed induction generator-based wind generation resources. A theoretical discussion serving as the mathematical premise for the proposed approach is presented. The driving point reactance, as seen from the WGR, across the subsynchronous frequency range is determined using four different approaches. Specifically, two of the four methods (Methods 3 and 4) are unique in terms of the approach utilized for performing frequency scans. System-side frequency scans are augmented with turbine-side frequency scans. A dynamic frequency-scanning method for the turbine side is developed which takes the turbine nonlinearities and its active behavior into account. The presence of crossover points in the reactance scans, as obtained from four approaches, in conjunction with the turbine-side frequency scans is utilized to draw conclusions on potential SSCI concerns. A portion of the Electric Reliability Council of Texas grid model has been utilized for the case study. The observations/inferences drawn via the reactance scans are corroborated via electromagnetic transients simulations.