A unified optimal controller design of TCSC to improve the power system dynamic stability

This paper presents a new method to assess power system's dynamic stability using a dynamic energy exchange concept between components in a power network. Using this method, a unified optimal controller design in time-domain for a thyristor controlled series capacitor (TCSC) is proposed to improve subsynchronous resonance (SSR) and low frequency oscillations with multi-modes in an interconnected electric power transmission line. Using only local measurements, the proposed design permits to control the variation of energy exchanged between the generator and electric network during dynamics under small disturbance, so it can improve interactions between them. A simplified systematic power network model is derived with an approximate TCSC dynamic model for controller design. Finally, the proposed TCSC controller is applied to an IEEE benchmark model to verify the theoretical concept.