Pole-restraining controlled active infeed converter with integrated power-quality improvement for AC-ship grids

The impact of power-electronic devices in naval applications is growing steadily. In combination with the available low short-circuit power, the converters-here, pole-restraining controlled-have to guarantee power quality within these grids. Concerning reactive power, voltage levels and frequency control conventional power-plant control mechanisms can be adapted - which are not discussed here. Concerning harmonics, the characteristics of converters allow effective harmonic mitigation. The set-point value generation for the converter current harmonics is, here, based on the FBD power theory. Its basic idea is to load all harmonics contained in the power grid voltages with clearly defined resistive currents. In this way, a damping effect is ensured. In contrast to usual active-filtering technologies which compensate one load or a group of loads based on measured currents, the suggested set-point value generation bases only on the voltages at the connection point of the converter.