Probability of small-signal stability of power systems in the presence of communication delays

This paper presents a probabilistic approach to evaluate the small-signal stability of power systems in the presence of communication delays. An exact method is first proposed to determine the relationship between delay margin and system parameters such as the system load. The delay margin is then modeled as a random variable and the probability density function (PDF) of the delay margin is determined based on the PDF of the load using a Monte Carlo simulation approach. The communication delays are assumed to be uniformly distributed in a practical range and the probability of system being small-signal stable for a given time delay is determined using the estimated PDF of the delay margin. The proposed method is applied to a single-machine-infinite bus (SMIB) power system with an exciter.