The unsolvable power flow problem is one of the basic issues in dispatching automation, which frequently appears in the process of grid mode planning and Optimal Power Flow (OPF) analysis. To deal with this problem, a...
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The unsolvable power flow problem is one of the basic issues in dispatching automation, which frequently appears in the process of grid mode planning and Optimal Power Flow (OPF) analysis. To deal with this problem, a practical adjustment method based on grid weak point is proposed in this paper. This method use “lower power injection” method to calculate a similar power flow solution which also the system maximum load level in unsolvable case. According this solution, the system weak point can be found by the index based on local system operation parameters and external equivalent system model. Combined with sensitivity analysis to reschedule the active power of generators and reactive power compensation devices, so as to make the system maximum load level increase, eventually get the system power flow solution at the original load level. This method overcome the large calculation of optimize algorithm in unsolvable power flow problem and can be applied to large practical grid. In the meantime, this method has clear physical interpretation, operator can be involved during the process, have great value in application. The method is tested on IEEE14 nods system.
A set of 4 in-vessel saddle coils are designed to generate a helical field onJ-TEXT tokamak to study the influences of external perturbation field to *** will be fed with alternating currents up to 1 0 kA at frequenci...
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A set of 4 in-vessel saddle coils are designed to generate a helical field onJ-TEXT tokamak to study the influences of external perturbation field to *** will be fed with alternating currents up to 1 0 kA at frequencies up to 1 0 *** the special structure,thermal environment and limited space in the vacuum chamber,it is of great essential to make sure that the coils will not be damaged whenundertaking the huge electromagnetic forces in the strong toroidal field and theirtemperatures don’t rise too much to destroy the insulation.A 3D finite element modelis developed by the ANSYS code in this paper,stresses are analyzed in the worstcondition,then a mounting method is *** results of the elastic and modalanalyses show that the mounting method meets the strength *** that,athermal analysis is performed to study the cooling process and the temperaturedistribution of the coils.
Pulse current technology has been widely used in plasma *** the low rate of rise of on-state current,the ordinary thyristor can be rarely used in pulse current *** order to reduce the requirement of current rising rat...
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Pulse current technology has been widely used in plasma *** the low rate of rise of on-state current,the ordinary thyristor can be rarely used in pulse current *** order to reduce the requirement of current rising rate of the switch,in this *** design a cylindrical air-core transformer for pulse plasma systems whose load can be usually equivalent to an inductor of low *** to the cored *** has the advantages of simple structure and no *** verifying the feasibility,we set up a testing system which consists of a 2.5kV/20μF capacitor,an ordinary thyristor and an air-core transformer which is shorted with an essentially inductive wire in the *** this *** the capacitor is discharged via the switch,the rate of current rising of the primary and secondary windings is 37A/μs and 138A/μs ***,the current rising rate of switch is 3.73 times lower than the load while the designed value is *** to the result of experiment,it is proved that making use of air-core transformer is an effective way to decrease the requirement of current rising rate of the switch.
Ice disaster has becoming a significant threat to power system security since recent years. Wireless sensor networks guarantee reliability of information communication under ice disasters, due to their self-organizati...
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ISBN:
(纸本)9781424496914
Ice disaster has becoming a significant threat to power system security since recent years. Wireless sensor networks guarantee reliability of information communication under ice disasters, due to their self-organization and the advantage that master stations are not involved. It is recommended to be applied on power grid structure security monitoring and assessment. It is proposed that different type of sensor nodes should be settled on overhead transmission lines, to comprehensively monitor mechanical status of a certain area. A two-layer sensor network model is presented for overcoming the communication range limitations of sensor nodes. Using the data obtained, a novel power system financial risk assessment method is proposed to balance the probability and seriousness of icing caused supports break, which helps grid structure progress in a long term.
Two poloidal arrays and a toroidal array of Mimov coils are developed on the J-TEXT tokamak to measure the magnetic fluctuations and study external MHD *** the Mimov coils data,the mode StnlCture and frequency can bc ...
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Two poloidal arrays and a toroidal array of Mimov coils are developed on the J-TEXT tokamak to measure the magnetic fluctuations and study external MHD *** the Mimov coils data,the mode StnlCture and frequency can bc detected and analyzed for the J-TEXT *** Singular Value Decomposition (SVD) technique has been successfully applied to the Mimov coils data to determine (m,n) of the mode.
A familiar technique for shortening the length of discharge from a capacitor in a pulsed power circuit involves a combination of opening and closing switches. Lengthening the pulse normally involves using a number of ...
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A familiar technique for shortening the length of discharge from a capacitor in a pulsed power circuit involves a combination of opening and closing switches. Lengthening the pulse normally involves using a number of relatively small capacitors, interconnected through inductors, with the resulting arrangement often being complex. The paper describes how using a capacitor as the energy source, it is possible to use the same basic and straightforward assembly of mutually- coupled inductors and switches to provide either pulse shortening or extension, merely by means of a different switching sequence. The concepts underlying both possibilities are explained and typical experimental results are presented.
It is considered that the plasma breakdown is relevant to the initial density of free *** electron injection system via ExB drift aimed at increasing the initial free electrons is designed and constructed on the J-TEX...
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It is considered that the plasma breakdown is relevant to the initial density of free *** electron injection system via ExB drift aimed at increasing the initial free electrons is designed and constructed on the J-TEXT tokamak to investigate this *** Cxperiments demonstrated that the system works well and some improvement has been obtained at start-up scenano.
作者:
Guodong WangMinghai LiuXiwei HuXiaoqin SongState Key Laboratory of Advanced Electromagnetic Engineering and Technology
Huazhong University of Science and TechnologyWuhan 430074People''s Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and TechnologyHuazhong University of Science and TechnologyWuhan 430074People''s Republic of China School of physics
Huazhong University of Science and TechnologyWuhan 430074People''s Republic of China School of physicsHuazhong University of Science and TechnologyWuhan 430074People''s Republic of China
The absorbing property of a three—dimensional metamaterial operating at 12.7GHz is investigated numerically by the model of double C-shaped metallic stripes,which are printed on the each side of a dielectric cube ***...
The absorbing property of a three—dimensional metamaterial operating at 12.7GHz is investigated numerically by the model of double C-shaped metallic stripes,which are printed on the each side of a dielectric cube *** carefully adjusting the dimensions of the metamaterial structure,the metamaterial simultaneously has both negative electric and magnetic response to an incident electromagnetic(EM)wave,and can exhibit left—handed property in a frequency rang with negative permittivity and permeability ***,Full-wave EM simulation demonstrates that it carl achieve over 99.6%absorption at 1 2.7GHz with a 0.4GHz full width at half *** metamaterial structures are scalable to operate a significant portion of the EM spectrum spanning from radio to the near optical *** metamaterial can ease design and fabrication,especially at high *** proposed absorber possesses many potential applications such as bolometer,sub—wavelength imaging,and microwave absorption.
A soft X-ray pulse height analysis(PHA) system has been designed and installed on J-TEXT tokamak for the study of electron temperature and *** system contains three Silicon Drift Detectors(SDD),a multi-channel analyze...
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A soft X-ray pulse height analysis(PHA) system has been designed and installed on J-TEXT tokamak for the study of electron temperature and *** system contains three Silicon Drift Detectors(SDD),a multi-channel analyzer(MCA), vacuum chamber,data collection procedure and off-line data processing program.A 60ms temporal resolution of electron temperature and the line radiation from moderate and high Z metallic impurities can be obtained by PHA *** on this system the performances of electron temperature and impurity have been investigated in J-TEXT ohmic heated plasmas.
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