8 research outputs found
Electromechanical Power Generation for Interplanetary Space Travel Beyond Low Earth Orbit
Preliminary results of investigating high frequency power generation using a permanent magnet synchronous machine is presented. The specific application is crew exploration vehicles for space travel beyond low earth orbit
Hybrid AC/DC Power Distribution Solution for Future Space Applications
As NASA readies itself for new space exploration initiatives starting with a human return to the Moon by the year 2020 eventually leading to human exploration of Mars, the requirements for a safe and reliable power system will become important issues. A preliminary study of a proposed hybrid AC/DC distribution system with a power electronic interface is investigated. A Static synchronous Compensator (STATCOM) is considered as the power electronic interface between the AC and the DC portions of the hybrid AC/DC distribution system. The system is modeled in EMTDC/PSCAD and tested for certain operating conditions and contingencies. High reliability and maintenance-free operation is crucial for continuity of supply on spacecraft distribution systems. Source redundancy is introduced to increase the reliability of the system. Some results pertaining to the distribution system are also presented
Creating Cascading Failure Scenarios in Interconnected Power Systems
The reported catastrophic failures of power systems from different geographical parts of the world often point to cascading outage events of system elements that eventually had led to system blackout. Although the initiating events of these cascading failures may, at times, be avoidable by vegetation management or proper protection settings, the occurrence of such an event as well as the eventual impact cannot always be predicted. There is much debate in the industry whether the operator has enough time to apply countermeasures to avoid blackouts. Besides, the process of determining effective countermeasures cannot be deemed accurate unless a system has been extensively studied for the occurrence of widespread blackouts. In this paper, methods to create different cascading failure scenarios are developed under credible contingency conditions. The methods are tested on the 118 bus test system and several cases are reported
AC/DC Power Systems with Applications in Future Human Habitat on Lunar and Mars Bases
As NASA readies itself for new space exploration initiatives starting with a human return to the Moon by the year 2020 eventually leading to human exploration of Mars, the requirements for a safe, efficient and comprehensive power system to support the exploration missions as well human habitat will become important issues to consider. Certain issues dealing with electric power generation and distribution on board Mars-bound vehicles and those on Lunar and Martian surfaces are described. The requirements for lightweight power generation dictates the use of a high frequency ac machine. Preliminary results of investigating the design of a permanent magnet synchronous machine is presented. ©2006 American Institute of Physic
Electromechanical power generation and AC/DC distribution for space application
Electromechanical energy conversion options for space applications are explored. A preliminary study of a proposed hybrid AC/DC distribution system with a power electronic interface is also investigated. A design methodology is introduced which will be helpful to evaluate specific choices for materials as well as machine configurations. Permanent Magnet (PM) Machine and Induction Machine (IM) operating at high frequencies are the two options considered for this purpose. A higher operating frequency has the advantages of higher power and energy densities. Various design aspects affecting the operating characteristics of machine are considered while developing the design methodology. The effects and consequences of specific trade-offs in the design process are studied --Abstract, page iii
On Oberbeck's vortices
The detailed structure of the liquid-vortices produced by Oberbeck's experiments has been studied in this paper. An automatic arrangements was introduced into the apparatus, so that the same vortex could be reproduced any number of times. The stream-lines in the moving liquid were traced by colouring its specific parts, and these were photographed at various stages of the motion. The space-time relationship was obtained by cinematographic films with an arrangement for recording time. A longitudinal section of the moving liquid shows that the stream-lines have the form of a double-spiral advancing through time liquid and at the same time presenting an increased number of convolutions, and followed by a "tail." The "tail" contracts, and after a time the spirals close up, and the moving liquid is transformed to an anchor-shaped vortex and is tiredly dissipated away. It appears that there are three distinct stages in the life-history ot the vortex. In the first stage it is under the influence of the tube, in the second stage it is freely developing uninfluenced by the boundary, and in the third stage it transforms itself into an anchor-shaped vortex and meets with dissolution. Each of these stages is associated with a distinct change in the structure and the rotational motion of the vortex. These have been studied in detail in this paper. A mathematical theory has been given which explains the essential features of the motion