Improved 48-pulse static synchronous compensator for high-voltage applications

A modified three-level 48-pulse +/- 100 MVAr static synchronous compensator (STATCOM) employing four pairs of elementary six-pulse neutral-point diode-clamped gate turn-off thyristor-based voltage source converters with fundamental frequency switching modulation is realised using angle control methodology and pre-calculated dead angle (the duration in which converter-terminal voltage is clamped to zero) in d-q synchronous rotating frame. With a magnetics configuration designed for summing up of output voltages of four converter pairs and simultaneously stepping up of its voltage to the transmission level, and employing proportional and integral controllers in the control, the operating performance equivalent to 96-pulse STATCOM is achieved through optimising harmonics distortion. This compensator is modelled and its performance is simulated in MATLAB using SimPowerSystem toolbox for voltage regulation in transmission system. The obtained results show reasonably good characteristics of the compensator to control system dynamics under steady-state and dynamic system conditions.