James F. Maguire

Development and Demonstration of a HTS Power Cable to Operate in the Long Island Power Authority Transmission Grid

The US Department of Energy is currently funding the design, development and demonstration of the first long length, transmission level voltage, cold dielectric, high temperature superconductor power cable. The cable is designed for permanent installation in the long island power authority (LIPA) grid and will be able to carry 574 MVA at a voltage of 138 KV. The project is led by American Superconductor and the team is comprised of Nexans, Air Liquide and LIPA. This paper will describe the goals of the project, an overview of the cable design, refrigeration system and site design. It will also include the statistics of the HTS wire manufactured for this project, the results of the qualification testing on a prototype 30 meter cable and the preparation work of the refrigerator system. The cable will be completed and put into service in the LIPA grid in 2007.

Development and demonstration of a long length HTS cable to operate in the long island power authority transmission grid

The US Department of Energy is currently funding the design, development and demonstration of the first long length, transmission level voltage, cold dielectric, high temperature underground superconductor power cable. The cable is designed for permanent installation in the Long Island Power Authority (LIPA) grid and is being designed to carry 574 MVA at a voltage of 138 kV. The project is led by American Superconductor and the team is comprised of Nexans, Air Liquide and LIPA. This paper describes the goals of the project, and an overview of the cable design, refrigeration system and site system requirements. It also includes a discussion of the influence of transmission network requirements, such as fault currents, on the design of the cable.

Installation and Testing Results of Long Island Transmission Level HTS Cable

The first long length, transmission level voltage, cold dielectric, high temperature superconductor power cable has been successfully installed in the Long Island Power Authority (LIPA) grid. The cable is capable of carrying 574 MVA at a voltage of 138 KV. Three 600 m long phase conductors were manufactured and shipped to the LIPA site. The installation process included pulling three cables through three separate 600 m long underground conduits and assembly of three terminations at each end. The project has been funded by the US Department of Energy and is led by American Superconductor. The project team is comprised of Nexans, Air Liquide and LIPA. This paper describes the cable system, installation process and an overview of various testing results before and after installation. In addition, details of an initial successful cool-down process are presented. It also includes the performance results in grid operation.

Development and Demonstration of a Fault Current Limiting HTS Cable to be Installed in the Con Edison Grid

The US Department of Homeland Security is currently funding the design, development and demonstration of an inherently fault current limiting HTS cable, called Secure Super Grids, under the Hydra project with Con Edison. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be built using cable system experience gained by AMSC and Ultera (a Southwire and nkt Cables joint venture) on previous projects. The underground cable will be permanently installed and energized in New York City in 2010. The project is led by American Superconductor who is teamed with Ultera and Con Edison. This paper describes the general goals and design criteria of the project. An overview of the concept of Secure Super Grids and advantages of this type of cable are presented in a grid-based network modeling. In addition, the design issues such as tailoring of the HTS wire to provide adequate thermal stability and electrical properties both under normal operation and during a fault are presented.

Progress and Status of a 2G HTS Power Cable to Be Installed in the Long Island Power Authority (LIPA) Grid

Underground high temperature Superconductor (HTS) power cables have attracted extensive interest in recent years due to their potential for high power density. With funding support from the United States Department of Energy (DOE), the worlds first transmission voltage level HTS power cable has been designed, fabricated and permanently installed in Long Island Power Authority (LIPA) grid. The HTS cable was successfully commissioned on April 22, 2008. In 2007, a new DOE Superconductor Power Equipment (SPE) program to address the outstanding issues for integrating HTS cables into the utility grid was awarded to the current project team (LIPA II). The goal of the LIPA II is to develop and install a replacement phase conductor manufactured using AMSCs second generation wire. In addition to the replacement of the phase conductor, the team will also address the outstanding components development necessary for full scale integration into a power grid including integral management of thermal shrinkage of the cable conductor, optimization of the cryostat design to mitigate the implications of potential cable damage, and the development and demonstration of a field splice in the operating utility grid and modular higher efficiency refrigeration system. This paper will report on the progress and status of LIPA II program. In addition, in-grid operation experience of existing 1G HTS Power cable is presented.

Power applications of high-temperature superconductors: status and perspectives

The potential of superconductors to have a revolutionary impact on how electric power is generated, delivered and used has long been recognized. The first superconducting power-grid application to achieve full commercial status is superconducting magnetic energy storage (SMES); the magnets of these systems have so far been fabricated primarily with metallic low-temperature superconductors (LTS). Although LTS prototypes have been demonstrated for motors, generators, power cables, transformers and current limiters, high-temperature superconducting (HTS) systems offer striking economic and system reliability advantages and are now seen as the central vehicle for broad commercialization of superconductivity in the power grid. Operating at temperatures from 30 to 80 K, they open the door to highly simplified cryogenics and increased stability, which result in economic systems not feasible with LTS. HTS prototypes at commercial power levels have already been demonstrated, particularly power transmission cables and motors. Key merits as well as remaining open technical challenges for such HTS applications are reviewed in this paper.

Development of a Pressure Box to Evaluate Reusable-Launch-Vehicle Cryogenic-Tank Panels

A cryogenic pressure-box test machine has been designed and is being developed to test full-scale reusable launch vehicle cryogenic-tank panels. This machine is equipped with an internal pressurization system, a cryogenic cooling system, and a heating system to simulate the mechanical and thermal loading conditions that are representative of a reusable launch vehicle mission profile. The cryogenic cooling system uses liquid helium and liquid nitrogen to simulate liquid hydrogen and liquid oxygen tank internal temperatures. A quartz lamp heating system is used for heating the external surface of the test panels to simulate cryogenic-tank external surface temperatures during re-entry of the launch vehicle. The pressurization system uses gaseous helium and is designed to be controlled independently of the cooling system. The tensile loads in the axial direction of the test panel are simulated by means of hydraulic actuators and a load control system. The hoop loads in the test panel are reacted by load-calibrated turnbuckles attached to the skin and frame elements of the test panel. The load distribution in the skin and frames can be adjusted to correspond to the tank structure by using these turnbuckles. The seal between the test panel and the cryogenic pressure box is made from a reinforced Teflon material which can withstand pressures greater than 52 psig at cryogenic temperatures. Analytical results and tests on prototype test components indicate that most of the cryogenic-tank loading conditions that occur in flight can be simulated in the cryogenic pressure-box test machine.

Fault Management of a Cold Dielectric HTS Power Transmission Cable

High temperature superconductor (HTS) power transmission cables offer significant advantages in power density over conventional copper-based cables. As with conventional cables, HTS cables must be safe and reliable when abnormal conditions, such as local and through faults, occur in the power grid. Due to the unique characteristics of HTS power cables, the fault management of an HTS cable is different from that of a conventional cable. Issues, such as nitrogen bubble formation within lapped dielectric material, need to be addressed. This paper reviews the efforts that have been performed to study the fault conditions of a cold dielectric HTS power cable. As a result of the efforts, a fault management scheme has been developed, which provides both local and through faults system protection. Details of the fault management scheme with examples are presented

Design, Development, and Testing of a Cryogenic Reciprocating Expansion Device

A lightweight, easily maintained helium expander system has been developed to provide reliable, low cost refrigeration in the 20 K to 40 K temperature range. The expander consists of a 2 inch diameter piston controlled by a combined hydraulic/pneumatic system. During the expansion process some of the energy released from the helium gas is stored in the hydraulic system. The stored energy is used to return the piston to its lower position. The expander assembly is built as a self- sealed removable pod that can be replaced with a new pod without warming or contaminating the main system. The expansion engine is controlled by a processor, which reads an LVDT signal and opens and closes valves in a timed sequence. The LVDT rod moves up and down with the piston giving a signal to the processor which controls the valve timing logic. This design is unique in the sense that the pressure of the gas after expansion can be easily adjusted by the valve timing. The hydraulic nature of the drive mechanism also allows us to compensate for the high back-pressure during the resetting of the piston. A typical reverse Brayton cycle operates with a compressor discharge of 1.7 MPa and a suction pressure of.1 to.138 MPa. This system is designed with the option of a higher suction pressure, allowing for higher throughput at similar power input. An adiabatic efficiency of 60% was demonstrated during testing.

Design and Fabrication of a Zero Gravity Liquid Cryogen Cooler Using Surface Tension Confinement Technology

AET, Ltd. was contracted by NASA GSFC to design and fabricate a zero gravity liquid cryogen cooler for use in NASA’s Hitchhiker Program. The cooler was designed to fit inside a standard Get Away Special (GAS) canister located in the cargo bay of the space shuttle. The main function of the cooler is to provide an inexpensive way for commercial customers and the research community to perform cold temperature testing in a zero gravity environment. Surface Tension Confinement Technology used in the design of the cooler, allows a liquid cryogen to be used as the cooling media without the traditional problems associated with the use of fluids in zero gravity. The paper discusses the design of the cooler, the testing results, and the epoxy joint design criteria that was developed during the contract, for a specific epoxy joint used in the design of the cooler.