For the realization of a low-carbon-emission society and in terms of energy security, the grid connections of electric power systems are highly desired by applying a smart grid and high voltage dC transmission systems...
For the realization of a low-carbon-emission society and in terms of energy security, the grid connections of electric power systems are highly desired by applying a smart grid and high voltage dC transmission systems (HVdC). If switching devices with a break down voltage (BV) greater than 10kV are realized, it would be extremely beneficial for the reduction in size and loss of the power electronics components such as a loop power controller (LPC), a static synchronous compensator (STATCOM), and an intelligent solid state transformer (SST). Silicon carbide (SiC) is expected to be a next-generation power semiconductor material because its band gap is three times larger than that of Si. The breakdown electric field of SiC is 10 times higher than that of Si, allowing the thickness of the drift layer in SiC powerdevices to be 1/10 that of Si powerdevices. Thus, if an insulated-gate bipolar transistor (IGBT) structure of SiC is used, it will be possible to realize more than 10 kV MOS-controlled switching devices with very low on-resistance [1, 2]. We have been working on a SiC p-channel IGBT with a BV of 10 kV [4] as well as a PiN diode with a BV of 13 kV [5]. For these devices, a high-quality n++ substrate could be used fordevice fabrication. However, the crystal quality of the p++ SiC substrate for the purpose of fabricating an n-channel IGBT is currently very poor with a high micropipe density and high resistivity using it as a collector. Moreover, the channel mobility for a SiC-MOSFET is still very low compared with that of a Si-MOSFET because of its 10-times higher interface-state density (dit). To solve these problems related to n-channel SiC-IGBTs, we employed a heavily doped epitaxial p++ layer as a substrate and an implantation and epitaxial MOSFET (IEMOSFET) [5, 6] as a MOSFET structure, which is called a flip-type IE-IGBT. For the substrate, we attempted to fabricate a flip-type wafer utilizing a p++ epitaxial layer as a substrate [1]. First, a 150-mm-thick
The investigation of multi-crystalline silicon （mc-Si） surface etching technology is a key point in solar cell research. In this paper, mc-Si surface was etched in the common alkaline solution modified by an additiv...
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The investigation of multi-crystalline silicon （mc-Si） surface etching technology is a key point in solar cell research. In this paper, mc-Si surface was etched in the common alkaline solution modified by an additive for 20 minutes at 78-80~C. Samples＇ surface morphology was observed by scanning electron microscope （SEM）. It is firstly found that the etched mc-Si surface has the uniform distribution of trap pits although the morphologies of trap pits are slightly different on different crystallographic planes. Si （100） plane was covered with many small Si-mountaln ranges or long V-shape channels arranged in a crisscross pat- tern. For （110） plane and （111） plane, they were full of a lot of triangle pit-traps （or quadrilateral holes） and twisted earthworm trap pits, respectively. The measuredreflectance of the sample was 20.5% at wavelength range of 400--900 nm. These results illustrate that alkaline solution modified by an additive can effectively etch out trap pits with a good trapping light effect on mc-Si surfaces. This method should be very valuable for mc-Si solar cells.
The lightning damage is one of the most serious problems for wind turbine generator systems anddistribution/transmission lines. direct lightning strokes to a wind tower or a blade frequently cause damages in the wind...
The lightning damage is one of the most serious problems for wind turbine generator systems anddistribution/transmission lines. direct lightning strokes to a wind tower or a blade frequently cause damages in the wind turbine generator systems. direct lightning strokes to a distribution line have been considered for lightning protection design. The lightning back-flow current is also an important factor for the lightning protection design of a distribution line. Thus, the lightning protection design of a wind turbine generator system must consider lightning overvoltages coming from a distribution line anddamage to the distribution line. Insulation coordination should be considered forrational lightning protection design. This paperdiscusses an insulation coordination design of a wind turbine and a distribution line. Simulations are carried out by the EMTP for such parameters as lightning current and grounding resistance.
There are lots of attempts in automotive field to supersede mechanical parts with electrical ones owing to increasing needs of drivers' safety, comfort and convenience as well as recent tightened environmental reg...
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There are lots of attempts in automotive field to supersede mechanical parts with electrical ones owing to increasing needs of drivers' safety, comfort and convenience as well as recent tightened environmental regulation. In addition, continuous improvements of semiconductortechnology make it speed up to use electric components instead of conventional mechanical and hydraulic ones. In accordance with these tendencies, the demand of electric power and energy used in vehicle has been increasing steadily, and it will cause overburden of conventional 14 V power generation anddistribution system. A research on higher voltage system started in early 1990s and 42 V power system has been introduced for a future automotive power-net. In this paper, technical trend in energy storage system which implies one of the key technologies to implement 42 V power-net is reviewed, anddevelopment results of the improved energy storage system consisted of ultracapacitor, battery and management controllers are presented
This paperdescribes about the multi-level BTB converter system installed in the powerdistribution system with the dispersed generation, such as solarpower, windpower, or others. This type of generation is often in...
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This paperdescribes about the multi-level BTB converter system installed in the powerdistribution system with the dispersed generation, such as solarpower, windpower, or others. This type of generation is often installed at the end of the powerdistribution system. This makes the current flow in the powerdistribution system unexpected profile and sometimes cause too much high voltage. To avoid such phenomenon, installation of a power flow controller is one of the solutions. However smallness, lightness and low cost is indispensable. We propose to use the multi-level BTB converter system with the new PWM control as the power flow controller or STATCOM
To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers, However, the second harmonic component in fault current i...
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To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers, However, the second harmonic component in fault current is increased by the introduction of underground 500kV lines. This paperdescribes a new method to discriminate internal fault from inrush current by the sum of active power flowing into transformers from each terminal. The average power is almost zero for energizing, but an internal fault consumes large power. To check the performance of this method, actual inrush current and voltage waveforms of 500/154kV transformer are accurately measured by digital equipment. The usefulness is confirmed by applying the method to the measured inrush and simulated fault data.
作者：
EMErY, FTWU, JLDr. Franklin T. Emery:is a senior engineer in the Electromechanical Systems Department at the Westinghouse R&D Center
Pittsburgh Pa. Dr. Emery received his B.S. (1974) M.S. (1977) and Ph.D. (1983) degrees in electrical engineering from the University of Pittsburgh Pittsburgh Pa. His primary work is in applied research on electrical systems associated with large power systems both for Navy ship applications and for the commercial power industry. He is presently involved in the development of the electronics for a high current high speed interrupter for use in the protection of power distribution systems on board Navy surface ships. His prior experience is in fiber optic technology design and application for both SDI and Navy applications. He is a Senior Member of IEEE and is a professional registered engineer in Pennsylvania and Florida. Dr. Jiing L. Wu:is a senior research scientist in the Electromechanical Systems Department at the Westinghouse R&D Center
Pittsburgh Pa. Dr. Wu received his B.S. degree in mechanical engineering from Taiwan Cheag Kung University Taiwan in 1965 M.S. in mechanical engineering from the University of Wisconsin Madison in 1969 and Ph.D. in engineering science from the State University of New York Buffalo New York in 1974. He has participated in research and development work in pulsed power switching devices for electromagnetic launchers circuit breakers for commercial and naval electrical systems and fault current limiting devices. He is presently the principal investigator and project manager of a team developing the current limiting protector for the Naval Sea Systems Command.
A pyrotechnic current limiting interrupter (CLI) has been developed for use in high current, 60-Hz, 480-volt, 3-phase electrical bus circuits. The interrupterdesign combines a high continuous current (4800 A rms) rat...
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A pyrotechnic current limiting interrupter (CLI) has been developed for use in high current, 60-Hz, 480-volt, 3-phase electrical bus circuits. The interrupterdesign combines a high continuous current (4800 A rms) rating with a high current (210 kA rms sym.) interruption capability. Its electrical power loss is low and its mechanical construction uses no complex moving mechanisms. The CLI is used with a current sensor, electronic logic, and energy storage circuitry. The current sensor continuously monitors the current through the CLI and provides input to logic circuits which analyze anddetermine the validity of the fault condition. Both the fault current magnitude andrate of current increase are used in combination to make the decision when to activate the CLI. Using stored electrical energy, a detonator is activated causing an explosive cord to generate shock waves sufficient to cut the current carrying conductors. detection and initiation of the interruption process occurs within 1/4 cycle for a symmetrical fault and within 1/2 cycle for an asymmetrical fault. The first peak in the fault current is limited to the first half cycle.
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