A comparative study of control strategies for fast voltage regulation with STATCOMs

This paper presents a comparison of linear and nonlinear control strategies for a STATCOM to act as an instantaneous reactive current source. The STATCOM is modeled as a three phase inverter along with a DC bus and inductive line-side filters. The dynamic response of the DC bus voltage is limited by the allowable magnitude of charging and discharging currents inside the STATCOM. The linear controller proposed is designed using LQR for the small-signal STATCOM model. The nonlinear controller is designed using a Lyapunov based strategy. Large signal analysis is presented for the nonlinear controller to show exponential regulation of the system states. Simulation results of the controlled STATCOM integrated with a distribution system model compare performance of the controllers designed.