The effect of communication delays on the frequency stability of power systems integrated with inverter air conditioners

Abstract

Massive inverter air conditioners (IACs) are widely integrated into the smart grid, which can be employed to provide frequency support. However, the participation of IACs may inevitably introduce communication delays in the process of data detection and transmission, which easily leads to oscillation and instability of power systems. In this paper, we explore a delay-dependent stability of the power system with the participation of IACs and further reveal the impact of delay in the IACs control loop during the frequency regulation. Initially, a linear time-delay system based on the state-space model is established, making it possible to investigate the effect of delays by a time-domain method. Then, applying Lyapunov theory and linear matrix inequality technique, a delay-dependent stability criterion is proposed, considering the tradeoff between accuracy of delay margins and computational efficiency. Finally, the interactive effects among delay margin and PI controller gains are explored in different scenarios and the validity of the proposed criterion is verified, with a less computational burden that can achieve nearly accurate delay margins. The proposed criterion supplies reference for determining the delay requirement and selecting controller parameters of IACs participating in frequency regulation.