Power Dense HTS Networks Designs for Contingencies and Resiliency of Electric Transport Systems
Abstract : The ability of HTS cable networks to provide a solution for the high power density requirements of electric transportation applications was explored. The high current density and the temperature-dependent critical current features of HTS cables were shown to allow resilient designs for power distribution in electric transportation applications. Heat loads at the terminations are shown to be the primary challenge. Appropriate designs in terms of ampacities of the current leads are essential in using the beneficial features of HTS cables. Thermal network models were used to understand the implications of using HTS cables to carry the necessary additional current to mitigate contingencies and to aid in the designs of effective HTS cable networks for electric aircraft and ships.
? It requires real-time response; far fewer outages and power quality disturbances; more transmission and distribution capacity; better use of existing capacity; less grid congestion; and enhancements that enable new power supplies, both central-station and distributed energy resources, to be brought on-line to deliver electricity for meeting the growing requirements of the economy.
? Existing time scales are too long (typically every five minutes) which restricts operational flexibility and response.
? One activity will be an assessment of baseline conditions in the industry for interoperability. Subsequent activities will assess accomplishments that enable industry to go beyond existing baseline levels.
? The architecture of the cable system causes an HTS cable to come across multiple cryogenic nodes throughout its length.
? Aided by the long lengths of cables (approximately 100 m), the temperature gradient along the length of the cable could be significant.
? A large temperature gradient is detrimental because the critical current of a cable is dictated by its hottest point.
? Increasing/decreasing the operating current from the design current of the terminal lead will result in higher than optimal heat loads because the current leads are typically optimized for minimum heat load at normal operating current using the McFee process
• There will be an annual internal assessment, validated every other year by independent peer review, of the costs of implementing an advanced operational concept to be cost competitive with today’s operational solutions.
• Initial activities will include an assessment of baseline values and the associated costs of a proposed innovative operational strategy.
• Subsequent activities will assess the yearly progression toward the goals.
• These reviews are conducted at least once every two years. Portfolio and risk analysis reviews assess program directions and priorities.
? The superconducting electrical system can perform only if the necessary cryogenic system is operational.
? The selection and design of the cryogenic system are thus of great importance, and both the electrical and cryogenic systems must be designed together. Failure in either the electrical and/or thermal system can affect the reliability and performance of the power system.
? Power systems must be designed to operate in the event of a device failure or during the routine maintenance of the components.
? Another important factor to consider when incorporating HTS cables in transport systems is that unlike in traditional power systems where cables often run point to point, electric transport applications are likely to consist of multiple HTS cables connecting at common nodes.
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