Predictive Control of Power Electronics Autotransformer for Mitigating Three-Phase Grid Current Unbalance in Railway Supply Systems

In order to mitigate the unbalance of three-phase grid currents that is commonly prevalent in single-phase railway supply lines, a predictively controlled power electronics autotransformer is proposed in this paper. It comprises of a pair of back to back single-phase voltage source converters that are strategically connected between different phases of the three-phase grid. Using finite control set model predictive control, the converters are intelligently controlled with a regulated DC link, to draw balanced sinusoidal three-phase grid currents at nearly unity input power factor, even as the rail system connects as a single-phase load on the three-phase network. This in turn helps in maintaining the balance and quality of three-phase voltage supply at the point of common coupling.