Development of synchronized control for multiple 2 MVA AC/AC converters

In this paper a full digital control for high performances modular power converters is developed. As a matter of fact, to increase output power, control strategy can parallel two or more power converters assuring, at the same time, optimum current sharing among them. If one of the paralleled converters fails, the control architecture can detect anomalous system behaviour, identify the converter in trouble and, switching it off, assuring continuous operation in power derating conditions. Moreover since master and slave converters are identical both in software and hardware configuration, if the master converter fails the supervision system can decide to give its function to another converter of the paralleled structure. This is a nice feature since it allows a high degree of availability and the possibility to restore the normal system behaviour avoiding plant shutdown. A full set of measurements, performed on a system prototype, shows the good dynamic performances of the voltage control loop of the master converter and of the current control loop of the slave converter, both in case of dq control and proportional + resonant control.