Impact of high-depth penetration of wind power on low-frequency oscillatory modes of interconnected power systems

This paper investigates impact of high-depth penetration of wind power, i.e., up to 30%, on low-frequency (0-2 Hz) oscillatory modes of interconnected power systems. The wind power is integrated as large Wind Power Plants (WPPs) based on Type-3 and Type-4 wind units represented by enhanced generic nonlinear and linearized models. The studies are based on eigen analysis of the 16-machine/68-bus NPCC equivalent system with multiple WPPs added to it. The case studies consider different ratios of Type-3/Type-4 WPPs to investigate impact of interaction between WPPs adopting different technologies on power system low-frequency dynamics. The studies reveal that WPPs can (i) noticeably impact the damping ratios of existing inter-area oscillatory modes at low-depth penetrations more than at high-depth ones, (ii) introduce new low-frequency oscillatory modes and (iii) cause instability by interacting with existing controllers in the system.