Variable-frequency transformer: Difference between revisions

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A '''variable-frequency transformer''' ('''VFT''') is used to transmit [[electric power|electricity]] between two ([[asynchronous]] or synchronous) [[alternating current]] [[frequency]] domains. The VFT is a relatively recent development, first deployed in 2004. Most asynchronous grid inter-ties use [[high-voltage direct current]] converters, while synchronous grid inter-ties are connected by lines and "ordinary" transformers, but without the ability to control power flow between the systems.

==Projects==

Five small variable-frequency [[electrical transformer|transformer]]s with a total power rate of 25 MVA were in use at [[Neuhof Substation]], Bad Sachsa, Germany for coupling power grids of former East and [[West Germany]] between 1985 and 1990.

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AEP Texas installed a 100 MW VFT substation in [[Laredo, Texas|Laredo]], Texas, [[United States]] ({{Coord|27|34|13.64|N|99|30|34.98|W|}}) in early 2007. It connects the power systems of [[ERCOT]] (in the United States) to [[Comisión Federal de Electricidad |CFE]] (in Mexico). (See [http://www.ettexas.com/projects/vft.asp The Laredo VFT Project].)

[[General Electric]] installed a 3 × 100 MW VFT substation in [[Linden, New Jersey]], in the United States ({{Coord|40|38|0.03|N|74|12|46.04|W|}}) in 2009. It connects the power systems of PJM & NYISO. This installation is in parallel with three existing phase-shifting transformers to regulate synchronous power flow. (See [http://www.geenergyfinancialservices.com/LindenVFT_Inauguration.asp The Linden VFT Project].)

Smaller VFTs are used in large land-based [[wind turbine]]s, so that the turbine rotation speed can vary while connected to an [[electrical distribution]] grid.

==Linden VFT==

[[General Electric]] installed a 3 × 100 MW VFT substation in [[Linden, New Jersey]], in the United States ({{Coord|40|38|0.03|N|74|12|46.04|W|}}) in 2009. It connects the power systems of [[PJM Interconnection|PJM]] & New York Independent System Operator (NYISO). This installation is in parallel with three existing phase-shifting transformers to regulate synchronous power flow.<ref>{{cite web (See [|url=http://www.geenergyfinancialservices.com/LindenVFT_Inauguration.asppress_releases/view/140 The|title=GE Lindento VFTOffer Project].Additional Electric Transmission Capacity from its Smart Grid Transformers at New Jersey Power Plant |author=<!--Staff writer(s); no by-line.--> |date=11Dec2012 |website=GE Energy Financial Services Press Release |accessdate=07Apr2014}}</ref>

==Economics of energy trading==

VFTs provide the technical feasibility to flow power in both directions between two grids, permitting [[electricity exchange|power exchanges]] that were previously impossible. Energy in a grid with lower costs can be transmitted to a grid with higher costs (higher demand), with energy trading. Power capacity is sold by providers. Transmission scheduling rights (TSRs) are auctioned by the the transmission line owners.

Financial Transmission Rights (FTRs) are a financial instrument used to balance energy congestion and demand costs.

==Construction and operation==

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==See also==

*[[Induction regulator]]

==References==

{{reflist}}

==External links==