What is Instability

Today's power systems have been extended due to interconnections with the neighboring systems. Energy cost is increasing due to greater sensitivity of new transmission lines. These have demanded the search of new controllers. These objectives were met by reactive power control on transmission lines. Hence, FACTS controllers are becoming an important part of the modern power transmission systems. Different control techniques are in use with STATCOM to generate control signals. But the conventional controllers like P; PI provide a slow dynamic response during the fault condition. This chapter creates an awareness of control issues and proposes an observer-based state feedback controller for STATCOM. The mathematical explanation of the observer-based state feedback controller for STATCOM is presented. Simulations have been carried out with one case study in MATLAB/SIMULINK environment. The simulation results show that the observer-based state feedback controller gives better performance than conventional PI controller during contingency condition.