Robust Decentralized Switching Power System Stabilisers for Interconnected Power Grids: Stability Using Dwell Time

This paper addresses the problem of designing decentralized robust power system stabilisers for interconnected power systems by considering effects of parameter variations and interconnections from other generators. To make the controller robust against parameter variations around an operating point, variations in system parameters due to the load change are translated to the uncertainty framework and are represented using Integral Quadratic Constraints (IQCs). The operating range of the generator is divided into several zones with respect to its power output and separate controllers are designed for each zone to achieve robust stabilization in the vicinity of the operating point. As the operating point shifts from one zone to another a suitable controller is selected and switched. The stability of the switched system is achieved by allowing a “dwell time” between consecutive switchings. Jumps in system states during switching are taken into account in the derivation of the dwell time. Interconnection effects due to other machines in the grid are included as the uncertainty in the controller design. The controller design methodology is validated by simulating a two-area power benchmark power system.