A 100-MW Variable Frequency Transformer (VFT) on the Hydro-Québec TransÃ\x89nergie Network - The Behavior during Disturbance

The Langlois project is the world\´s first application of the "variable frequency transformer" (VFT) technology, which was successfully commissioned on the Hydro-Quebec TransEnergie (HQTE) system in the spring of 2004. The VFT consists of a rotary transformer, for continuously controllable phase shift, together with a drive system and control that adjust the angle and speed of the rotary transformer to regulate the power flow through the VFT. The VFT system provides a means to control power flow between asynchronous grids. This paper show\´s how the VFT reacts to grid disturbances by showing curves of real events like single phase to ground faults, three phase faults, islanding, how its natural reaction helps weak networks by comparing the results of a simulation of the network with and without the VFT.