Synchrophasor-enabled power grid restoration with DFIG-based wind farms and VSC-HVDC transmission system
An innovative system restoration strategy using doubly-fed induction generator-based wind farms is proposed. The strategy involves retention of charge in the DC bus following a blackout and `Hot-Swapping' between direct flux control mode and conventional grid-connected mode, which does not require resetting of any controller dynamic states and avoids the need for energy storage. An autonomous synchronisation mechanism enabled by remote synchrophasors is also proposed. A blacked-out system, which includes a wind farm and a voltage source converter (VSC)-HVDC connected to a network unaffected by blackout, is used as the study system. Transmission line charging and load pickup is performed using the wind farm in flux control mode while the VSC-HVDC system conducts the same process for another portion of the system. The proposed `Hot-Swapping' and autonomous synchronisation approach is applied to connect the two parts of the grid and switch the wind farm to grid connected mode of operation. The results are demonstrated in a hybrid co-simulation platform where the aforementioned system is modelled in EMT-type software and the rest of the network is represented in a phasor framework.