Energy storage systems (ESSs) play a very important role in recent years. Flywheel is one of the oldest storage energy devices and it has several benefits. Flywheel Energy Storage System (FESS) can be applied from very small micro-satellites to huge power networks. A comprehensive review of FESS for hybrid vehicle, railway, wind power system, hybrid power generation system, power network, marine, space and other applications are presented in this paper. There are three main devices in FESS, including machine, bearing, and Power Electronic Interface (PEI). Furthermore, advantages and disadvantages all of them have been presented. In addition a brief review of new and conventional power electronic converters used in FESS, have been discussed. Finally, practical ways to develop this technology in the future are presented.

A comprehensive review of Flywheel Energy Storage System technology

Meeting NASA's N+3 goals requires a fundamental shift in approach to aircraft and engine design. Material and design improvements allow higher pressure and higher temperature core engines which improve the thermal efficiency. Propulsive efficiency, the other half of the overall efficiency equation, however, is largely determined by the fan pressure ratio (FPR). Lower FPR increases propulsive efficiency, but also dramatically reduces fan shaft speed through the combination of larger diameter fans and reduced fan tip speed limits. The result is that below an FPR of 1.5 the maximum fan shaft speed makes direct drive turbines problematic. However, it is the low pressure ratio fans that allow the improvement in propulsive efficiency which, along with improvements in thermal efficiency in the core, contributes strongly to meeting the N+3 goals for fuel burn reduction. The lower fan exhaust velocities resulting from lower FPRs are also key to meeting the aircraft noise goals. Adding a gear box to the standard turbofan engine allows acceptable turbine speeds to be maintained. However, development of a 50,000+ hp gearbox required by fans in a large twin engine transport aircraft presents an extreme technical challenge, therefore another approach is needed. This paper presents a propulsion system which transmits power from the turbine to the fan electrically rather than mechanically. Recent and anticipated advances in high temperature superconducting generators, motors, and power lines offer the possibility that such devices can be used to transmit turbine power in aircraft without an excessive weight penalty. Moving to such a power transmission system does more than provide better matching between fan and turbine shaft speeds. The relative ease with which electrical power can be distributed throughout the aircraft opens up numerous other possibilities for new aircraft and propulsion configurations and modes of operation. This paper discusses a number of these new possibilities. The Boeing N2 hybrid-wing-body (HWB) is used as a baseline aircraft for this study. The two pylon mounted conventional turbofans are replaced by two wing-tip mounted turboshaft engines, each driving a superconducting generator. Both generators feed a common electrical bus which distributes power to an array of superconducting motor-driven fans in a continuous nacelle centered along the trailing edge of the upper surface of the wing-body. A key finding was that traditional inlet performance methodology has to be modified when most of the air entering the inlet is boundary layer air. A very thorough and detailed propulsion/airframe integration (PAI) analysis is required at the very beginning of the design process since embedded engine inlet performance must be based on conditions at the inlet lip rather than freestream conditions. Examination of a range of fan pressure ratios yielded a minimum Thrust-specific-fuel-consumption (TSFC) at the aerodynamic design point of the vehicle (31,000 ft /Mach 0.8) between 1.3 and 1.35 FPR. We deduced that this was due to the higher pressure losses prior to the fan inlet as well as higher losses in the 2-D inlets and nozzles. This FPR is likely to be higher than the FPR that yields a minimum TSFC in a pylon mounted engine. 1

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Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Electric vehicles (EVs) have recently been significantly developed in terms of both performance and drive range. There already are various models commercially available, and the number of EVs on road increases rapidly. Although most existing EVs are charged by electric cables, companies like Tesla, BMW and Nissan have started to develop wireless charged EVs that don’t require bulky cables. Rather than physical cable connection, the wireless (inductive) link effectively avoids sparking over plugging/unplugging. Furthermore, wireless charging opens new possibilities for dynamic charging – charging while driving. Once realised, EVs will no longer be limited by their electric drive range and the requirement for battery capacity will be greatly reduced. This has been prioritised and promoted worldwide, particularly in UK, Germany and Korea. This paper presents a thorough literature review on the wireless charging technology for EVs. The key technical components of wireless charging are summarised and compared, such as compensation topologies, coil design and communication. To enhance the charging power, an innovative approach towards the use of superconducting material in coil designs is investigated and their potential impact on wireless charging is discussed. In addition, health and safety concerns about wireless charging are addressed, as well as their relevant standards. Economically, the costs of a wide range of wireless charging systems has also been summarised and compared.

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A critical review on wireless charging for electric vehicles

Review on Energy Storage Systems Control Methods in Microgrids

Conceptual design of hybrid-electric transport aircraft

We have been carrying out a saturable iron core reactive type superconducting fault current limiter (SFCL) development program since 2002. The major two disadvantages that people used to be foretold for a saturable iron core reactive type SFCL are the massive use of iron (resulting in large size, heavy weight, and high cost) and the high induced voltage hazard to the dc superconducting coil (this may damage the current supply of the dc bias) as a fault takes place. We have found the ways to deal with these two problems, making such kind of equipment reliable and cost effective. In this paper, we will report the technical data and testing results of a 3 phase lab testing model. Some key design parameters of the 35 kV/100 MVA prototype will also be presented.

Development of Saturated Iron Core HTS Fault Current Limiters

This work covers the high-temperature superconducting (HTS) technologies based on the highlights in recent achievements in the applied HTS field in China. Its comprehensive coverage includes practical HTS material manufacturing and characterization, large-scale applications, and electronic applications. The applied HTS technologies have been well enabled to build applicable devices, and their characteristics have been well verified in the HTS devices developed to be industrialized for practical applications. The highlighted HTS devices and their performance details reveal the trend and the necessary improvement required to reach the goal of industrial applications of HTS technologies.

Enabling High-Temperature Superconducting Technologies Toward Practical Applications

Superconducting magnetic energy storage (SMES) technology has been progressed actively for use in modern power system. Principal application schemes of a sole SMES system, a hybrid energy storage system (HESS) consisting of small-scale SMES and other commercial energy storage systems (ESSs), a distributed SMES (DSMES) system, and a distributed HESS (DHESS) are presented and compared. The concept of the SMES-based HESS provides an economical way to apply medium-scale SMES systems in daily load leveling and to apply small-scale SMES systems in power quality improvement. A dc power distribution network case with superconducting dc cables and SMES devices is conceptually designed to evaluate the performance of the proposed four SMES application schemes. The results show that the novel concept of the SMES-based DHESS can be particularly expected to achieve efficient and economical power management. Finally, the application prospects and possible schemes implanting SMES devices for power generation, transmission, distribution and utilization are explored for use in future smart grid.

Integrated SMES Technology for Modern Power System and Future Smart Grid

A 220 kV/300 MVA saturated iron-core superconducting fault current limiter (SI-SFCL) has been successfully manufactured and installed at Shigezhuang substation in Tianjin, China Because it is the first time SI-SFCL has been used at such a high voltage level, extensive testing was carried out to assess the safety and functional performance of the device in the HV power grid Two categories of tests were conducted at the factory before the SFCL was shipped to the installation site One was to examine whether the device met the relevant industrial standards, such as lightning impulse, high voltage withstanding, partial discharging, and temperature rising, etc The other was to determine the functional performance and key operational parameters, such as measuring steady impedance, magnetizing and demagnetizing the superconducting coil, and so on Following the completion of the installation at the substation, field tests were performed to re-confirm performance after the stages of disassembly, shipment, and reassembly on site This paper introduces the major results of these tests

Factory and Field Tests of a 220 kV/300 MVA Statured Iron-Core Superconducting Fault Current Limiter

The active saturated iron-core superconducting fault current limiter (SISFCL) is one of the best solutions to coping with high fault current levels and may be helpful in building future smart distribution networks. The application of an SISFCL in a distribution system can reduce the fault current to an acceptable level when a short-circuit fault occurs at different positions. The operational principle and the current-limiting characteristic of an active SISFCL are briefly introduced in this paper. The influence of an active SISFCL on the conventional inverse and definite time-delay overcurrent protective relays is discussed. In order to maintain reliable operation of the distribution system with an SISFCL, the protection coordination and setting solution is proposed. A model of a real 35-kV distribution system with an active SISFCL was built and simulated with the Electro-Magnetic Transients Program including DC software. Simulation tests have demonstrated the correctness and validity of theoretical analyses.

Ying Xin

Papers

Development of Saturated Iron Core HTS Fault Current Limiters

Enabling High-Temperature Superconducting Technologies Toward Practical Applications

Integrated SMES Technology for Modern Power System and Future Smart Grid

Factory and Field Tests of a 220 kV/300 MVA Statured Iron-Core Superconducting Fault Current Limiter

Overcurrent Protection Coordination in a Power Distribution Network With the Active Superconductive Fault Current Limiter