Large power analysis of switched reluctance machine system for coal mine

The conventional structures in the Switched Reluctance machines are introduced, such as three-phase 12/8 structure Switched Reluctance machine, three-phase 6/4 structure Switched Reluctance machine, four-phase 16/12 structure Switched Reluctance machine, and four-phase 8/6 structure Switched Reluctance machine. Three-phase 12/8 structure Switched Reluctance machine is the best choice for the large power Switched Reluctance machine system in coal mines. The asymmetric bridge power converter main circuit and the bifilar winding power converter main circuit are also introduced. Three-phase asymmetric bridge power converter main circuit is the best choice for the large power Switched Reluctance machine system in coal mines. The magnetic paths of the designed large power motor are given with one phase excitation and double phases excitation. The phase current waveforms are also given.

Structured Microgrids (SμGs) and Flexible Electronic Large Power Transformers (FeLPTs)

Structured microgrids(SμGs)and Flexible electronic large power transformers(FeLPTs)are emerging as two essential technologies for renewable energy integration,flexible power transmission,and active control.SμGs provide the integration of renewable energy and storage to balance the energy demand and supply as needed for a given system design.FeLPT’s flexibility for processing,control,and re-configurability offers the capability for flexible transmission for effective flow control and enable SμGs connectivity while still keeping multiscale system level control.Early adaptors for combined heat and power have demonstrated significant economic benefits while reducing environmental foot prints.They bring tremendous benefits to utility companies also.With storage and active control capabilities,a 300-percent increase in bulk transmission and distribution lines are possible without having to increase capacity.SμGs and FeLPTs will also enable the utility industry to be better prepared for the emerging large increase in base load demand from electric transportation and data centers.This is a win-win-win situation for the consumer,the utilities(grid operators),and the environment.SμGs and FeLPTs provide value in power substation,energy surety,reliability,resiliency,and security.It is also shown that the initial cost associated with SμG and FeLPTs deployment can be easily offset with reduced operating cost,which in turn reduces the total life-cycle cost by 33%to 67%.

Research on the variable speed system of large power alternating current motor

The development status of the variable speed system of large power AC(alternating current)motor drive in China is introduced.The large power AC drive fed by AC-AC converters(cycloconverters)has developed greatly,and some innovations on the theory and engineering technique have been realized.They have been applied to rolling mills,mine hoists,and so on,and remarkable economic and social benefit has been achieved.The development of AC drive fed by large power IGCT(integrated gate commutated thyristors)AC-DC-AC converter is also introduced.It has excellent performance and reliable operation,and has been used in traction.

Study on Large Power Tractor Driver's Heart Rate and Fatigue in Sowing Work

In order to reduce the driving fatigue in sowing work, this paper based on heart rate （HR） as the main indicator to survey, tested and analyzed the fatigue condition of the drivers of three imported tractors and one domestic tractor in sowing work. The results showed that when driving the imported tractors in sowing work, the HR increasing rate was 10.4%-14.3%, labor intensity belonged to the light level; when driving domestic tractor in sowing work, the HR increasing rate was 23.4%-33.0%, it was remarkably bigger than that of driving imported tractors （P〈0.05）, labor intensity belonged to the middle level. The main effects on driving fatigue included the control methods, tractors＇ cab environment, processing time, operating content, and so on. Finally, we proposed the concrete measures and suggestions to reduce driving fatigue and improve drivers＇ work condition.

Investigation on some key problems of large power AC-DC-AC converter

China is an important country in iron and steel industry.Power electronics converters are widely used.For the cold rolling mills of high speed,AC-DC-AC converters should be used.In the paper,the design and the control system of the large power three-level AC - DC - AC converter with IGCTs is investigated,and a back-to-back large power three-level AC - DC - AC converter with IGCTs has been got. With a series experiments,the performance of the converter is examined.The experiment result indicates the converter reaches the design requirement and it shows excellent performance.The converter system has been put into use safely.It is estimated that the AC - DC - AC converter system will be used in the drive systems for rolling mills in the near future.

Xiangfan Coal-fired Power Plant - a matched large power plant for Three Gorges Project starts to construct

Xiangfan Coal-fired Power Plant, a key energy construction project matched with Three Gorges Project, approved by the State Council. formally started to build in the suburb of Xiangfan City, Hubei Province on November 29, 1996.

Constructing Large Capacity Power Plant on Collapsible Loess Stratum with Huge Thickness

1 Preface In the northern and northwestern parts of China, quite a large portion of area, approximately 630,000 km^2, is covered by loess and loess-liked soils. The loess thickness ranges from several meters to several hundred meters along the river’s terraces to those geomorphologic plateaus. In geology, "China Loess" has become a geologic term, because the loess in China has evolved with the widest distribution and greatest thickness in the world, and is also a typical and significant deposit in Quaternary Period.

Forward modeling for “earth-ionosphere” mode electromagnetic field

A fixed artificial source(greater than 200 kW) was used and the source location was selected at a high resistivity region to ensure high emission efficiency. Some publications used the "earth-ionosphere" mode in modeling the electromagnetic(EM) fields with the offset up to a thousand kilometer, and such EM fields still have a signal/noise ratio of 10-20 dB. This means that a new EM method with fixed source is feasible, but in their calculation, the displacement in air was neglected. In this work, some three-layer modeling results were presented to illustrate the basic EM fields' characteristics in the near, far and waveguide areas under "earth-ionosphere" mode, and a standard is given to distinguish the boundary of near, far and waveguide areas. Due to the influence of the ionosphere and displacement current in the air, the "earth-ionosphere" mode EM fields have an extra waveguide zone, where the fields' behavior is very different from that of the far field zone.

Universal single-mode lasing in fully chaotic two-dimensional microcavity lasers under continuous-wave operation with large pumping power [Invited]

For a fully chaotic two-dimensional(2D) microcavity laser, we present a theory that guarantees both the existence of a stable single-mode lasing state and the nonexistence of a stable multimode lasing state, under the assumptions that the cavity size is much larger than the wavelength and the external pumping power is sufficiently large. It is theoretically shown that these universal spectral characteristics arise from the synergistic effect of two different kinds of nonlinearities: deformation of the cavity shape and mode interaction due to a lasing medium. Our theory is based on the linear stability analysis of stationary states for the Maxwell–Bloch equations and accounts for single-mode lasing phenomena observed in real and numerical experiments of fully chaotic 2D microcavitylasers.

Towards a (More) Electronic Transmission and Distribution (eT&D)

The challenges and the path towards a(more)electronic transmission and distribution(eT&D)is presented in this paper.The challenges are first identified together with key stakeholders in the drive for grid modernization.A fundamental question is then asked about the investment priority.Six basic characteristics are reviewed,leading to the composition of structured microgrids as the basic functional cell of a modern grid.One example of fractal radial structure and one fractal meshed structure are presented.The likely evolution path is then proposed together with basic technology sets.Specific foundation technologies are discussed in detail,including adiabatic power conversion,3MC technology,medium voltage conversion,distribution-level electronic power transformer and FACTs hardware integration,and back-to-back converters as a universal interconnect element.The rapidly emerging on-wire sensing technology is also discussed.It is pointed out that the distribution-level large electronic power transformer will provide a key component to enable hybrid ac/dc grid flow control and ancillary support for a flexible electronic transmission and distribution(eT&D)systems.

AlN/GaN high electron mobility transistors on sapphire substrates for Ka band applications

We report the DC and RF characteristics of AlN/GaN high electron mobility transistors（HEMTs） with the gate length of 100 nm on sapphire substrates. The device exhibits a maximum drain current density of 1.29 A/mm and a peak transconductance of 440 m S/mm. A current gain cutoff frequency and a maximum oscillation frequency of 119 GHz and 155 GHz have been obtained, respectively. Furthermore, the large signal load pull characteristics of the AlN/GaN HEMTs were measured at 29 GHz. An output power density of 429 m W/mm has been demonstrated at a drain bias of 10 V. To the authors＇ best knowledge, this is the earliest demonstration of power density at the Ka band for Al N/Ga N HEMTs in the domestic, and also a high frequency of load-pull measurements for Al N/Ga N HEMTs.