James Michael Fogarty

AC losses in a high temperature superconducting generator

As part of the DOE-SPI funded project a commercial HTS utility-size generator is being developed based on GEs iron core superconducting generator technology. The iron core concept has significant advantages over air core designs. The rotor consists of a cold superconducting field coil and coil supports and a warm iron core, which takes the torque and transmits to the shafts. Heat load due to AC losses in the cold mass of the rotor are a key design constraint. Analyses have been performed both at the component and system levels. AC loss tests have been conducted on an HTS generator. This paper presents and discusses the analytical and test results.

Quench Test of HTS Coils for Generator Application at GE

When a synchronous generator connected to the power grid experiences a fault, it is required to stay on line, ride through the fault, and be able to carry full rated field current when the fault is cleared. The peak current during these events could be 2 times higher than the normal operating current. This may cause an HTS rotor coil to go into normal state and generate Joule heating. If the fault event is short enough and the heat dumped can be carried away by the cooling system, the coil may recover to the superconducting state at the end of the fault. Otherwise, the coil may thermally run away, or dasiaquenchpsila. To investigate the quench behavior of the HTS rotor coil of the 100 MVA generator at GE Global Research Center, a 1.5 MVA prototype coil was developed and tested to quench under different conditions. The experiment design, set up, tests and test results are presented in this paper.

Critical current degradation in HTS wires due to cyclic mechanical strain

HTS wires, which may be used in many devices such as magnets and rotating machines, may be subjected to mechanical strains from electromagnetic, thermal and centripetal forces. In some applications these strains will be repeated several thousand times during the lifetime of the device. We have measured critical current degradation due to repeated strain cycles for both compressive and tensile strains. Results for BSCCO-2223 HTS conductor samples are presented for strain values up to 0.5% and cycle numbers up to and beyond 10/sup 4/.

Over-Current Simulation Test for High Temperature Superconducting Generator

A small high temperature superconductor (HTS) coil was designed and tested at GE-Global Research Center (GE-GRC) to evaluate the over-current capability for HTS generator rotor. The superconducting rotor coil is a layer-wound racetrack coil using the BSCCO 2223 conductor. Over-current simulation tests have been done to simulate the fault operation condition for generator based on the previous analysis work. The obtained data is used to evaluate the performance of HTS material in generator applications

Wind generators as compared to large heavy duty power generators

Wind turbine generators are different than conventional thermal turbine-generators both in the types of machines used as well as the type of application and environment in which the machines operate. The wind generator and its converter have several common configurations, rotor types, and operational duties that are not commonly encountered in large power plants. Those differences are discussed in regard to machine design aspects, such as winding insulation, as well as environmental factors and maintenance factors.

Development and Test of a Prototype 100MVA Superconducting Generator

In 2002, General Electric and the US Department of Energy (DOE) entered into a cooperative agreement for the development of a commercialized 100 MVA generator using high temperature superconductors (HTS) in the field winding. The intent of the program was to: • Identify and develop technologies that would be needed for such a generator. • Develop conceptual designs for generators with ratings of 100 MVA and higher using HTS technology. • Perform proof of concept tests at the 1.5 MW level for GE’s proprietary warm iron rotor HTS generator concept. • Design, build, and test a prototype of a commercially viable 100 MVA generator that could be placed on the power grid. This report summarizes work performed during the program and is provided as one of the final program deliverables.