Impact of Communication Delay and Sampling on Small-Signal Stability of IBR-rich Power Systems

The growing adoption of inverter-based resources (IBRs) has introduced unprecedented dynamics in power systems, resulting in oscillations across a broad spectrum of frequencies. Communication delay between the plant-level control and the inverter-level control in IBR plants has been recognized as one of the causes of such oscillations and a factor that impacts the system's stability. The control signals from the plant-level controller also experience sampling, with the sampled values held constant by the hold elements for the duration of the sampling period. This also has a bearing on the response of IBR plants. In this paper, we analyze the impacts of communication delay and sampling of control signals between plant-level control and inverter-level control of grid-following IBR plants on the small-signal stability of power systems. The underlying fundamentals of communication delay and sampling are revisited to explain the observed responses. Our findings emphasize the unique effects of communication delay and sampling period on the stability of IBR-rich power systems and suggest strategies to mitigate their detrimental impacts. The work also highlights the need for more accurate approaches for small-signal stability analysis of such systems.