Robust power system stabiliser design via interval arithmetic

In this paper, an interval arithmetic (IA) approach is proposed to rigorously address load uncertainties associated with the design of PSS. The proposed approach characterises the robust stabilising three-term/parameter PSSs computed for a single-machine infinite-bus system. A robust PSS can properly function over a wide range of operating conditions. Image-set and interval plant models are developed to express all uncertainties in the model parameters imposed by continuous variation in generation and load patterns. For robust PSS design purpose, an interval characteristic polynomial of the closed loop system is generated. Interval Routh-Hurwitz (RH) array is considered to get a fast but conservative calculation of the stability region in the controller-parameter plane using IA computation. Degenerate interval (RH) array for an image-set polynomial of the plant is thereafter developed where the region of robust stability is exactly computed. Simulation results are provided to confirm the effectiveness of the proposed approach in computing robust PSSs.