As a result of world's energy resources crisis and environment pollution increasingly aggravating, distributed generation (DG) based on renewable energy has become a developmental trend for electric power industry...
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As a result of world's energy resources crisis and environment pollution increasingly aggravating, distributed generation (DG) based on renewable energy has become a developmental trend for electric power industry in 21 century. However, DG's are usually affected by natural conditions being not able to output power continuously and steadily, so when large scale wind turbine generators are incorporated into the grid there is likely attendance impact it would bring on electric power system stability. In this investigation, the wind farm connection was done at 33/1 1kV level at Kastina substation located at Northern part of Nigeria. This paper is to establish voltage instability and frequency fluctuation that might be associated with the connection of the wind farm to the existing grid. The DigSILENT Power Factory software was used for modeling and simulation analysis of the studies and the results shows that when wind farm is connected to the grid, large clearance time is required for the fault to be cleared for voltage and frequency to become normalize again as compare with normal grid system. The studies has verified transient stability associated problem due to voltage and frequency stability variation phenomenon during the disconection of both windfarm and the load from the existing grid and is easier to predict in future the setting of protective devices and clearance time.
In order to ensure the safety of DFIG when severe fault happens, crowbar protection is adopted. But during slight fault condition, the crowbar protection will not trip, and the DFIG is still excited by AC-DCAC convert...
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Theoretical research and equipment development of traveling-wave fault location seriously depend on digital simulation. Meanwhile, the fault-generated transient traveling wave must be transferred through transmission ...
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One of the most important characteristic of triggered vacuum switch (TVS) is the breakdown voltage affecting the operation reliability of TVS. It depends on features, such as electrode material, electrode shape, gap d...
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A DC-excited high torque electromagnetic brake has been designed for high-speed train in WHMFC. An electromagnetic-thermal analysis model for electromagnetic brake analysis has been developed, taking into account the ...
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With series resonance occur though the inductor and capacitor, LLCL output filter could achieve better switching ripple filtering effect in the case of using less inductance obtained than LCL filter. This paper summar...
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With series resonance occur though the inductor and capacitor, LLCL output filter could achieve better switching ripple filtering effect in the case of using less inductance obtained than LCL filter. This paper summarizes the LLCL filter parameters design method in the application of shunt active power filter, and passive damping characteristics are analyzed. It is propose that under the precondition of ensuring the stability, choose lower damping resistance to maintain the high switching ripple attenuation capacity. In terms of control, generalized integral controller is used to realize compensation of within 50 odd harmonic in power current. Finally, the simulation result proved the effectiveness of LLCL filter and generalized integral controller.
Nine-switch converter, which can provide two sets of three-phase outputs with independent amplitudes, phases and frequencies, has been proposed to replace two independent three-phase converters for cost- and size-redu...
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ISBN:
(纸本)9781467351942
Nine-switch converter, which can provide two sets of three-phase outputs with independent amplitudes, phases and frequencies, has been proposed to replace two independent three-phase converters for cost- and size-reduced purposes. This paper proposes a hysteresis-modulation (HM) sliding-mode (SM) pulsewidth modulation (PWM) for the nine-switch converter. With the proposed HM-SMPWM, the phase currents of the two sets of outputs can track to their current references directly. To do this, decoupled sliding surfaces for the two sets of outputs are structured; based on the sliding surfaces, the proposed SMPWM are detailed explained; the operational range is also discussed; finally the experiments are carried out to confirm the effectiveness of analysis.
To clarify the dependence of arc duration on atmosphere, experiments were conducted under conditions of air, N2, Ar, He and CO2 with the pressure of 0.1MPa in a 14V/28V/42V circuit re spectively.A quantitative relatio...
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To clarify the dependence of arc duration on atmosphere, experiments were conducted under conditions of air, N2, Ar, He and CO2 with the pressure of 0.1MPa in a 14V/28V/42V circuit re spectively.A quantitative relationship between arc duration and gas parameters such as ionization po tential, thermal conductivity was obtained from the experimental ***, the inherent mechanism of influence of atmosphere on arc duration was discussed.
A new structure of damper based on magnetic fluid was proposed in the paper. The working principle and the damping property of the damper were analyzed. To simulate the levitation height of the permanent magnet in the...
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A new structure of damper based on magnetic fluid was proposed in the paper. The working principle and the damping property of the damper were analyzed. To simulate the levitation height of the permanent magnet in the magnetic fluid, the finite element method was adopted, obtained the curve that the levitation height of the permanent magnet changed with its diameter and length. To abtain the factors that affected the damping properties, the experiment tested the damping properties of magnetic fluid dampers in different specifications, analyzed the results of the experiment, found out the relationship between the damping properties and the original state of the cantilever as well as the size of the permanent magnet.
A fluid-thermal coupled analysis based on FEM is conducted. The inner structure of the coils is built with consideration of both the structural details and the simplicity;thus, the detailed heat conduction process is ...
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