The grid-connected converter(GCC) is widely used as the interface between various distributed generations and the utility grid. To achieve precise power control for GCC, this paper presents a model predictive direct p...
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The grid-connected converter(GCC) is widely used as the interface between various distributed generations and the utility grid. To achieve precise power control for GCC, this paper presents a model predictive direct power control(MPDPC)with consideration of the unbalanced filter inductance and grid conditions. First, the characteristics of GCC with unbalanced filter inductance are analyzed and a modified voltage control function is derived. On this basis, to compensate for the power oscillation caused by unbalanced filter inductance, a novel power compensation method is proposed for MPDPC to eliminate the DC-side current ripple while maintaining sinusoidal grid current. Besides, to improve the control robustness against mismatched filter inductance, a filter inductance identification scheme is proposed. Through this scheme, the estimated value of filter inductance is updated in each control period and applied in the proposed MPDPC. Finally, simulation results in PSCAD/EMTDC confirm the validity of the proposed MPDPC and the filter inductance identification scheme.
We analyze the electromagnetic interaction between local surface plasmon polaritons (SPPs) and an atmospheric surface wave plasma jet (ASWPJ) in combination with our designed discharge device. Before discharge, th...
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We analyze the electromagnetic interaction between local surface plasmon polaritons (SPPs) and an atmospheric surface wave plasma jet (ASWPJ) in combination with our designed discharge device. Before discharge, the excitation of the SPPs and the spatial distribution of the enhanced electric field are analyzed. During discharge, the critical breakdown electric field of the gases at atmospheric gas pressure and the surface wave of the SPPs converted into electron plasma waves at resonant points are studied. After discharge, the ionization development process of the ASWPJ is simulated using a two- dimensional fluid model. Our results suggest that the local enhanced electric field of SPPs is merely the precondition of gas breakdown, and the key mechanism in maintaining the discharge development of a low-power ASWPJ is the wave-mode conversion of the local enhanced electric field at the resonant point.
The Ar atmospheric pressure plasma was found to be an excellent laboratorial source for green aurora ***,the characteristic and production mechanism of the green aurora emission of the Ar atmospheric pressure plasma a...
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The Ar atmospheric pressure plasma was found to be an excellent laboratorial source for green aurora ***,the characteristic and production mechanism of the green aurora emission of the Ar atmospheric pressure plasma are still not *** this work,an Ar plasma in a long glass tube which emits intense green aurora light is *** the long glass tube,it can be concluded that the green aurora emission in the Ar plasma is not owing to the mixture of Ar plasma plume with the surrounding *** is also found that the green aurora emission often appeared beyond the active electrode when the active electrode is placed at the downstream of the gas *** green emission disappears when the traces amount of O_(2) or N_(2)(about 0.05%–0.07%)is added to *** is because the O_(2) molecules deactivate the upper state O(^(1)S),which results in the decrease of the green *** the other hand,when N_(2) is added,Ar metastable atoms are quenched by N_(2),which results in the decrease of O atoms and eventually leads to the decrease of the green emission *** intensity of the green aurora emission increases when the driving voltage frequency increases from 1 to 10 k *** importantly,it is found that the green aurora emission is not affected when a grounded stainless steel needle is in contact with the plasma ***,the green emission is not driven *** these findings are helpful for the understanding of the physics and its applications of atmospheric pressure plasma jet in space physics,laser physics and other application areas.
Generation of atmospheric pressure homogeneous air plasma in a large gap(>4 mm)is a *** this study,an atmospheric pressure homogeneous air plasma generated in a gap up to 10 mm is reported,which is based on a three...
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Generation of atmospheric pressure homogeneous air plasma in a large gap(>4 mm)is a *** this study,an atmospheric pressure homogeneous air plasma generated in a gap up to 10 mm is reported,which is based on a three-electrode configuration,where a high-voltage(HV)electrode and a middle electrode form a surface dielectric barrier discharge(S-DBD),and together with the ground electrode form the main volume ***-speed photographs confirm that the discharge in the main gap is *** gas temperature of the plasma estimated from the N_(2)(C^(3)∏_(u)-B^(3)∏_(g))(Δv=-2)emission is about 320 K,which is close to room temperature.A detailed analysis shows that the discharge ignited between the HV electrode and the middle electrode is serving as an electron source,and the electrons deposited on the dielectric plate are due to the S-DBD along with the applied voltage generating a driving force,which results in a high concentration of seed electrons in the main gap and induces the homogeneous *** analysis shows that the electric field in the main gap is only about18.45 k V·cm^(-1),which is much lower than the typical breakdown electric field of 30 k V·cm^(-1)for atmospheric pressure air discharge.
A non‐equal gap distance dielectric barrier discharge(DBD)between cone‐shape and a cylinder‐shaped electrodes is *** DBD is driven by a nanosecond voltage *** the pulse frequency is 500 Hz or lower,ladder‐shape pl...
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A non‐equal gap distance dielectric barrier discharge(DBD)between cone‐shape and a cylinder‐shaped electrodes is *** DBD is driven by a nanosecond voltage *** the pulse frequency is 500 Hz or lower,ladder‐shape plasma with multiple plasma layers is generated within the gap,with a distance increasing from 1 to 7 *** to high‐speed photographs of the plasma captured by an intensified charge‐coupled camera detector camera,the ladder‐shaped plasma is formed owing to propa-gation of ring‐shaped plasma from the region of the short‐gap distance to the region of long‐gap distance with regular variations in its propagation *** propagation speed drops to zero and lasts for about 20-30 ns at the region of each plasma layer,which results in bright plasma *** electric field of the plasma layer at the region of the different gap distance is evaluated according to the optical emission intensity ratio R_(391)/_(394)of N_(2)^(+)at 391 nm and N_(2) at 394 *** obtained electric field drops from 8.1 to 6.4 kV/mm when the plasma is propagated from regions of gap distance of 2-5 *** the pulse frequency is increased to 1 kHz or higher,the discharge changes into a filamentary mode and the multiple‐layer plasma disappears.
Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applicati...
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Electric power infrastructure has recently undergone a comprehensive transformation from electromagnetics to semiconductors. Such a development is attributed to the rapid growth of power electronic converter applications in the load side to realize energy conservation and on the supply side for renewable generations and power transmissions using high voltage direct current transmission. This transformation has altered the fundamental mechanism of power system dynamics, which demands the establishment of a new theory for power system control and protection. This paper presents thoughts on a theoretical framework for the coming semiconducting power systems.
A practical analytical model to calculate the switching loss of cascode gallium nitride high electron mobility transistors(GaN HEMTs)is *** facilitate analysis and application,the transmission delays introduced by Si ...
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A practical analytical model to calculate the switching loss of cascode gallium nitride high electron mobility transistors(GaN HEMTs)is *** facilitate analysis and application,the transmission delays introduced by Si MOSFET and interconnection inductances are ignored in ***,the nonlinear junction capacitances of the device and circuit stray inductances are also incorporated to increase the accuracy of the *** turn-on and turn-off switching processes are described in detail and the simplified equations can be easily solved by using mathematical *** on the analytical model,loss evaluation of totem-pole PFC converter is introduced ***,the accuracy of the model is validated by comparing the calculated loss and converter’s efficiency with experiment *** efficiency of 99.26%is achieved for a 3.6 kW single phase CCM Totem-Pole PFC AC/DC converter switching at 50 kHz based on 650 V cascode GaN HEMTs.
The plasma density feedback control system(PDFCS) has been established on the Joint Texas Experimental Tokamak(J-TEXT) for meeting the need for an accurate plasma density in physical *** consists of a density meas...
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The plasma density feedback control system(PDFCS) has been established on the Joint Texas Experimental Tokamak(J-TEXT) for meeting the need for an accurate plasma density in physical *** consists of a density measurement subsystem,a feedback control subsystem and a gas puffing *** to the characteristic of the gas puffing system,a voltage amplitude control mode has been applied in the feedback control strategy,which is accomplished by the proportion,integral and differential(PID) *** this system,the quantity calibration of gas injection,adjusted responding to the change of the density signal,has been carried *** experimental results are shown and discussed.
The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power ...
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The paper proposes a stochastic unit commitment(UC)model to realize the low-carbon operation requirement and cope with wind power prediction errors for power systems with intensive wind power and carbon capture power plant(CCPP).A linear re-dispatch strategy is introduced to compensate the wind power deviation from the spot *** robust optimization technique is employed to obtain a reliable commitment plan against all realizations of wind power within the uncertainty set given by probabilistic *** proposed model is validated with IEEE 39-bus *** advantages of flexible CCPPs are compared to the normal coal-fueled plants and the impacts of robustness controlling are discussed.
OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma ***,experimental studies on how ...
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OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma ***,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very *** this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)*** results show that the productions of OH and O increase and then decrease with the increase of O_(2)*** OH and O densities reach their maximum when about 0.8%O_(2)is *** increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster *** increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is ***,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O *** analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)*** addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.
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