Electric rail transit systems are the large consumers of energy. In trains with regenerative braking capability, a fraction of the energy used to power a train is regenerated during braking. This regenerated energy, if not properly captured, is typically dumped in the form of heat to avoid overvoltage. Finding a way to recuperate regenerative braking energy can result in economic as well as technical merits. In this comprehensive paper, the various methods and technologies that were proposed for regenerative energy recuperation have been analyzed, investigated, and compared. These technologies include: train timetable optimization, energy storage systems (onboard and wayside), and reversible substations.

Recuperation of Regenerative Braking Energy in Electric Rail Transit Systems

This paper presents the analysis of pulse load operation on the health of a simplified electric ship power system. Two scenarios of the pulse load operation, with and without an energy storage system have been addressed. The energy storage used is a flywheel as it has a very fast time response in supplying high power demands. The health of the electric ship power system is monitored by observing key indicators in the components critical to the working such as the generator and propulsion motor. The time-domain simulation of two test cases is carried out in the PSCAD/EMTDC software platform. The results underscore the vital importance of the flywheel energy storage system in maintaining the stability of the ship power system in the event of pulse load operation.

Impact of pulse loads on electric ship power system: With and without flywheel energy storage systems

A dynamic pressure air bearing which comprises a sleeve member, with a shaft member arranged coaxially therein. Air is introduced through a clearance between the sleeve member and the shaft member by the rotation of either the sleeve member or the shaft member, and the dynamic pressure of the air acts on the inner surface of the sleeve member and the surface of the shaft member. Ceramics cover at least one of the inner surface of the sleeve member and the surface of the shaft member. The ceramics include at least one type selected from among SiN, SiCN, SiC, SiO, TiN, TiC, TiCN, BN, BC, BCN, Al 2 O 3 , WC, and diamond.

Dynamic pressure air bearing

A hybrid bearing system that has a self-lubricating portion and a grease lubricated portion each being disposed on the same surface, the system is adapted to accommodate at least two distinct wearing forces generated by different types of motions. The bearing system comprises: a first member; a second member, the second member being configured to be rotatably received within the first member; a self lubricating machineable liner system disposed between the first member and the second member; a receiving area disposed on the self lubricating liner system and a portion of either the first or the second member; and a lubrication opening in fluid communication with the receiving area, the lubrication opening providing a means for disbursing a lubrication grease within the receiving area.

Hybrid bearing system

Grid integration of variable wind power is confronted with many challenges. Challenges and issues associated with large scale wind integration into the existing power grid are discussed in this paper. Different wind turbine technologies and their technical features are presented. A review of the state of the art energy storage technologies, their characteristic features and comparison are presented. Finally, application of a hybrid battery-supercapacitor based energy storage systems with a direct drive variable speed wind turbine is investigated and simulation results are presented.

Grid integration impacts and energy storage systems for wind energy applications — A review

PROBLEM TO BE SOLVED: To provide a flywheel energy storage which eliminates influence of running vibration, yawing, pitching, etc., at the time of being loaded on a self-running machine such as an electric motorcar, etc. SOLUTION: A rotary shaft 14 is arranged vertically within a device housing 9, and a discoidal flywheel 2 is integrated with the bottom of the rotary shaft 14. The rotary shaft 14 is supported rotatably by an upper ball bearing 16 and a lower ball bearing 17 of roller bearings, and a magnetic ball bearing 1 of a magnetic energizing means. The magnetic bearing 1 is a passive thrust magnetic bearing which constitutes a magnetic circuit of a magnetic rotor 25 and a magnetic stator 26, and it energizes the rotary shaft 14 upward with the energizing force corresponding to the weight of the rotary shaft 14, the flywheel 2, etc., and the pre-load of the lower ball bearing 17. Moreover, damping rings 19 and 20 of vibration attenuating means having large rigidity and an attenuating function are interposed between the device housing 9 and both ball bearings 16 and 17. COPYRIGHT: (C)1999,JPO

Flywheel energy storage

In an excimer laser apparatus comprising a laser chamber 1 filled with a laser gas, a discharge excitation portion 2 provided in the laser chamber 1 , a rotary shaft 3 to which a gas circulating fan 4 for circulating the laser gas is fixed, a shield partition wall 61 for forming a sealed space to enclose the rotary shaft 3 , a magnetic bearing of a control type including a rotor portion 32 provided on the rotary shaft 3 side and a stator portion 6 provided outside the shield partition wall 61 and serving to pivotally support the rotary shaft 3 in non-contact, a driving motor 13 provided outside the laser chamber 1 , magnetic coupling portions 33, 11 and 121 for transmitting driving force of the driving motor 13 to the rotary shaft 3 through the shield partition wall 61 in non-contact, and rotary shaft sensors 8 and 9 for detecting a position of the rotor portion 32 with respect to the stator portion 6 . The shield partition wall 61 of the magnetic coupling portions 33, 11 and 121 is formed of ceramic and the shield partition wall 61 of the magnetic bearing is formed of metal.

Excimer laser apparatus

PURPOSE: To reduce the size and facilitate the processing of a hybrid fluid bearing by providing dynamic pressure generating grooves on the bearing surface and coating the bearing surface with a film of a material optionally selected except the surface of the grooves to allow the introduction of a pressure fluid through the grooves to form a static pressure bearing. CONSTITUTION: The bearing surface 11 and the other surfaces stopping the ejection of the pressure fluid are coated with a ceramic film. The surface of dynamic pressure generating grooves is not coated with the ceramic film. The depth of the grooves is the same with the thickness of the ceramic film. The fluid pressure generated by the grooves 2 as the bearing or a member placed opposite to the bearing is turned provides dynamic bearing effect and the external pressure fluid introduced through the grooves 2 provides static bearing effect, thus providing a single bearing with both dynamic and static bearing effects. COPYRIGHT: (C)1980,JPO&Japio

Katsuya Toma

Papers

Flywheel energy storage

Excimer laser apparatus

Hybrid type fluid bearing