Coprime factorisation approach in designing multi-input stabiliser for damping electromechanical oscillations in power systems

The application of loop shaping in H_∞ control design through a dual-input power system stabiliser (PSS) in a benchmark power system model is demonstrated. The PSS stabilises two key system poles contributing to critical electromechanical oscillations involving turbine generators and electrical network. The IEEE First Benchmark Model has been considered in this study to demonstrate the effectiveness of the control. A linearised model of the system is pre- and post-compensated using loop-shaping approach. The problem of robust stabilisation of a normalised coprime factor plant description is formulated into a generalised H_∞ problem and the solution is obtained analytically. The performance of the controller shows robustness to electromechanical modes, which were otherwise very poorly damped or undamped depending on operating conditions. The robustness is further validated in Simulink, including nonlinearities and device saturation limits.