Research on one-cycle-controlled grid-connected inverter application on direct-drive wind power system

Direct-drive wind power system needs a full-scale power converter to transmit the variable frequency electrical power to the grid. In order to improve the low voltage ride through (LVRT) capability, the grid-connected inverter (GCI) should work at a unity, a leading or a lagging power factor. Traditional control methods are complicated and output waveform is distorted by dead time. This paper introduces the principle of one-cycle control (OCC) to the current control of grid-connected inverter. Active and reactive power can be controlled respectively. Dead time is unnecessary. Therefore the quality of output waveform is improved. Simulation and experiment are conducted to demonstrate the simplicity and effectiveness of the new method.