Analysis and Performance evaluation of Type 1 Fuzzy Reactive Current Controller with STATCOM

The STATIC Synchronous Compensator is a shunt connected Voltage source converter (VSC) uses self-commutating devices such as GTOs thereby utilized for reactive power control. The purpose of employing STATCOM at the midpoint of long transmission line is for the enhancement of power transfer capability and/or reactive power control at the load centre by voltage regulation. For reactive current control, the use of PI controller and nonlinear feedback controller is investigated. PI controller found to be causing oscillatory instability in inductive mode of operation of STATCOM and can be overcome by the nonlinear feedback controller wherein the transient response of the STATCOM depends on the controller parameters selected. There is always need for parameter optimization in nonlinear feedback controller. This paper presents a model free approach using fuzzy logic controller for reactive current control of STATCOM. The performance of the designed controller is evaluated by transient simulation. It is observed that the STATCOM with fuzzy logic controller shows excellent transient response for the step change in the reactive current reference. While the eigenvalue analysis and controller design are based on D-Q model, the transient simulation is based on D-Q of STATCOM (which considers switching action of VSC).