A Refined Frequency Scan Approach to Sub-Synchronous Control Interaction (SSCI) Study of Wind Farms

Frequency-scan approaches for conducting Sub-Synchronous Control Interaction (SSCI) studies of wind farms is becoming a normal practice in the industry. Modern power electronics control used in many wind generators has a characteristic that couples two frequency components, similar to saliency effects of conventional generators. As a consequence, treating both wind farm and grid as single-dimension impedances could generate an inaccurate result. This paper describes a two-dimension transfer function approach that can be practically applied to ensure accuracy when evaluating SSCI aspects of power-electronic equipment such as renewable generation.