A stochastic methodology for modeling PSS in small signal stability analysis

Traditionally the problem of small signal stability, also known as small disturbance stability, has been studied since the 1960´s by using a deterministic approach. However, the perturbations, as well as the behaviour of load and system components have a random nature, as they are difficult to predict both in amplitude and duration. In this paper we propose an approach based on an additive stochastic dynamic model that is able to capture, e.g., the randomness of loads. We consider the stochastic transient to a stationary `safety band´ that is then used to optimize system performance in dependence on the gain parameter of PSS. Results on a test system are presented and discussed.