Direct Power Control of an VHDC system based on VSCs

HVDC system based on voltage source converter (VSC-HVDC) is recently used in distribution systems to improve power system stability. In this paper Direct Power Control of three-phase pulse width-modulated rectifier and inverter without any voltage line sensors are discussed. Thanks to the idea of new synchronous double reference frame phase-locked loop (SDRF-PLL) approach, the control system is resistant to majority of line voltage disturbances. It is shown that the proposed DPC control is effective to damp system oscillations and enhance power quality when power flow is reversed.