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Vermont Electric Power Company recently commissioned a Synchronous Condenser based reactive power device in the Granite substation as part of the Northwest Vermont Reliability Project. The reactive power device consisted of four +25/-12.5 MVAr synchronous condensers and four 25MVAr shunt capacitor banks. This synchronous condenser based reactive power device was chosen over Static Var Compensators or STATCOM. This installation is significant in that it represents the first new conventional synchronous condenser provided by GE for a utility application in more than thirty years. This paper examines the needs surrounding the Granite Substation Reactive Power Device and provides a comparison of the different technologies considered. This paper also discusses both the technical and business reasons why synchronous condenser technology made the most sense in this application.Index Terms-Capacitor switching, Power system dynamic stability, Reactive power, Static VAR compensators, Synchronous condenser.P. Marken is with GE Energy,

A Variable Frequency Transformer (VFT) has been in full commercial operation on the Hydro-Québec TransEnergie system since December of 2004. The VFT is an interconnection device that is based on widely established technology. However, because the application of some equipment is unique, the maintenance requirements associated with VFT operation and ownership have become an item of interest. This paper provides information on the maintenance program that is being utilized at the Hydro-Québec Langlois VFT installation. This represents the expected maintenance requirements for a typical VFT installation and is meant to provide a guideline for comparison of maintenance requirements for other interconnection technologies.This paper also discusses the availability performance of the first VFT installation and how it has been calculated for the Hydro-Québec TransEnergie installation.The information presented in this paper reveals that the VFT is a simple and reliable interconnection device and does not require an extensive maintenance program. The availability performance of the VFT has been very good. The VFT should be considered a viable option for an interconnection device from a maintenance or reliability standpoint.