Research of STATCOM based on multi-winding-transformer-isolated converter

A main circuit topology of STATCOM(STATic synchronous COMpensator) is presented,which has N cascaded multi-winding-transformer-isolated converters.Each converter consists of one multi-winding transformer and M converters.Each multi-winding transformer has M secondary windings connecting with M converters separately.M × N converters share one capacitor.The proposed topology avoids both serial and parallel connection of devices,which improves device reliability effectively.The phase-shifted SPWM is used to decrease the harmonics in both output voltage and output current.The secondary windings of multi-winding transformer are not phase-staggered,which is accomplished by the controller of converter.A decoupling control scheme under constant reactive power operation mode is also proposed.Simulations with Matlab /Simulink verify the performance of proposed topology and the effectiveness of proposed control scheme.