GE recently completed the installation of variable frequency transformers (VFT) at the Linden, NJ cogeneration plant, owned by GE Energy Financial Services, which will allow power from the Pennsylvania-New Jersey-Maryland transmission system to flow into New York City.
|VFT rotary system. Click to enlarge.|
Each of the three variable frequency transformers, a GE smart grid technology, will facilitate the transmission of up to 100 megawatts of power for a total of 300 megawatts. This electricity will help stabilize New York City’s power grid and will provide unparalleled flexibility for utilities.
The VFT system is based on a combination of hydro generator and transformer technologies. It 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.
Smooth power control comes from regulating the torque through the drive system. Rotational speed is dictated by the difference in grid frequencies and generally will be below 3 rpm.
The variable frequency transformers precisely control the flow of power from one grid to another even in the smallest increments, helping utilities manage their operations more effectively in an ever-changing energy market with fluctuating electricity prices. These VFT units will increase system reliability, provide New Yorkers with access to more diversified and lower-cost power sources, and will reduce the need for new power plants within the city, where finding sites is difficult and construction costs are high.
The transformers are essential when moving power from one grid to another, as the “peaks and troughs” making up the voltage must “match”—which means the peaks must be synchronized in time.