The traditional PI controller for a hybrid energy storage system(HESS)has certain drawbacks,such as difficult tuning of the controller parameters and the additional filters to allocate high-and low-frequency power ***...
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The traditional PI controller for a hybrid energy storage system(HESS)has certain drawbacks,such as difficult tuning of the controller parameters and the additional filters to allocate high-and low-frequency power *** paper proposes a model predictive control(MPC)method to control three-level bidirectional DC/DC converters for grid-connections to a HESS in a DC ***,the mathematical model of a HESS consisting of a battery and ultra capacitor(UC)is established and the neutral point voltage imbalance of a three-level converter is solved by analyzing the operating modes of the ***,for the control of the grid-connected converters,an MPC method is proposed for calculating steady-state reference values in the outer layer and the dynamic rolling optimization in the inner *** outer layer ensures the voltage regulation and establishes the current predictive model,while the inner layer,using the model predictive current control,makes the current follow the predictive value,thus reducing the system current *** cascaded topology has two independent controllers and is free of filters to realize the high-and low-frequency power allocation for a ***,it allows two types of energy storage devices to independently regulate the voltage and realizes the power allocation of the battery and ***,simulation studies are conducted in PSCAD/EMTDC,and the effectiveness of the proposed HESS control strategy is verified in a case,such as a controller comparison and fault scenario.
In the reversely switched dynistor(RSD)-based pulse power circuits,a magnetic switch is usually necessary to be applied together with a main *** occupies space and needs a magnetic *** this paper,a method of designing...
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In the reversely switched dynistor(RSD)-based pulse power circuits,a magnetic switch is usually necessary to be applied together with a main *** occupies space and needs a magnetic *** this paper,a method of designing a RSD-based pulse circuit without a magnetic switch is *** the pulse circuit,a RBDT(reverse blocking diode thyristor)is used to separate the two capacitors and provide an energy *** pre-charge time of the RSD can be guaranteed by the energy conversion between the capacitors and inductors,instead of the saturation of the magnetic *** addition,the energy which is reused to trigger the RSD is based on an *** pulse circuit is evaluated by simulations and practical *** to the experimental results,the factors affecting the load pulse current and triggering of the RSD and RBDT are ***,a method to reduce the current in the trigger switch,which is a potential problem in the pulse circuit,is proposed.
The coexistence of pollution from coal-fired heating and inefficient utilization of renewable resources in northern China has raised great *** studies on heat-power systems are primarily focused on traditional combine...
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The coexistence of pollution from coal-fired heating and inefficient utilization of renewable resources in northern China has raised great *** studies on heat-power systems are primarily focused on traditional combined heat and power(CHP)systems and are limited to static energy flow analysis or the dynamic characteristics of a single system ***,it is difficult to make full use of the complementary potential of electrical energy and heat *** paper proposes a heat-power station(HPS)system based on renewable energy for the purpose of utilizing the surplus renewable energy to generate heat and meet heating *** overall architecture of the HPS system is established and its operational principle and dynamic characteristics of both the electrical and heating components in the system are analyzed and dynamic mathematical models are also *** addition,a coordinated electro-thermal control method based on system characteristics is designed to ensure the normal operation of a *** results verify the effectiveness of the model and control in the case of renewables fuctuation and heat load variations.
In this paper,the microgrid economic scheduling mathematical model considering the integration of plug-in hybrid electric vehicles(PHEVs)is presented and the influence of different charging and discharging modes on mi...
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In this paper,the microgrid economic scheduling mathematical model considering the integration of plug-in hybrid electric vehicles(PHEVs)is presented and the influence of different charging and discharging modes on microgrid economic operation is *** generic algorithm is used to find an economically optimal solution for the microgrid and PHEV *** scheduling of PHEVs and the microgrid are optimized to reduce daily electricity cost and the potential benefits of controlled charging/discharging are explored *** caused by vehicle utilization as well as technical limitations of distributed generation and energy storage system are taken into *** proposed economic scheduling is evaluated through a simulation by using a typical grid-connected microgrid model.
Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be *** paper proposes an open-loop phase sync...
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Currently,a grid-connected inverter is required to inject a dual-sequence current during asymmetric grid sags,which means both positive and negative sequence phases should be *** paper proposes an open-loop phase synchronization(OLS)method of positive and negative sequences for an asymmetric grid based on the moving average filter(MAF),which does not need to separate the positive and negative sequence fundamental components of grid *** a benefit,there is no double-frequency oscillation in the estimated phases at offnominal frequencies since the positive and negative sequence phases are obtained *** proposed method not only has the inherent advantages of OLS,but also further improves the dynamic response since the window length of MAF is only 1/6 of the fundamental *** effectiveness of the proposed OLS is verified by experimental results.
Cold atmospheric plasma(CAP)driven by pulsed high-voltage power has specific advantages in various fields,such as the growth promotion of edible fungi in plasma *** with other strains,Ganoderma lucidum has the signifi...
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Cold atmospheric plasma(CAP)driven by pulsed high-voltage power has specific advantages in various fields,such as the growth promotion of edible fungi in plasma *** with other strains,Ganoderma lucidum has the significant advantage of high medicinal value,but the shortcomings of low yield,long growth cycle,and an uneven market *** this study,Ganoderma lucidum was treated with a CAP powered by a homemade pulsed highvoltage power *** groups of Ganoderma lucidum were treated under different *** stalk lengths and pileus areas of Ganoderma lucidum were recorded to evaluate growth *** showed that treatment frequency affected growth status *** lucidum was treated with 40 s plasma once a week and showed an improved growth status with a 33.63%increase in average stalk length and a 28%increase in the number of individuals whose pileus areas was greater than the ***,the growth speed was ***,treatment at an excessive frequency would damage and slow down the growth of Ganoderma lucidum.
The Q-band (33-50 GHz) fast sweep frequency modulated continuous wave (FMCW) reflectometry has been recently developed for electron density profile measurement on the Joint TEXT tokamak. It operates in ordinary mo...
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The Q-band (33-50 GHz) fast sweep frequency modulated continuous wave (FMCW) reflectometry has been recently developed for electron density profile measurement on the Joint TEXT tokamak. It operates in ordinary mode (O-mode) with a 20 μs sweeping period, covering the density range from 1 × 10^19m 3 to 3 × 10^19m-3. On the bench test, a Yttrium Iron Garnet (YIG) filter is used for the dynamic calibration of the voltage controlled oscillator (VCO) to obtain a linear frequency sweep. Besides, the use of a power combiner helps to improve the sideband suppression level of the single side-band modulator (SSBM). The reconstructed density profiles are presented, which demonstrate the capability of the reflectometry.
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.
Acoustic signals contain rich discharge *** this study,the acoustic signal characteristics of transient glow,spark,and glow discharges generated through DC pin–pin discharge were *** signals were analyzed in the time...
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Acoustic signals contain rich discharge *** this study,the acoustic signal characteristics of transient glow,spark,and glow discharges generated through DC pin–pin discharge were *** signals were analyzed in the time,frequency,and time–frequency domains,and the correlation between the electric and the acoustic signal was studied *** results show that glow discharge does not produce measurable sound *** the other modes,with a decrease in the discharge gap,the amplitude of the acoustic signal increases sharply with mode transformation,the short-time average energy becomes higher,and the frequency components are more ***,the current pulse and sound pressure pulse have a one-to-one relationship in the transient glow and spark regimes,and they are positively correlated in amplitude.A brief theoretical analysis of the mechanism of plasma sound and the trends of signals in different modes is ***,the change in the discharge energy is closely related to the sound generation of the plasma.
Huazhong University of Science and technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions f...
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Huazhong University of Science and technology has developed an experimental setup of a radio frequency(RF) driven negative hydrogen ion source,to investigate the physics of production and extraction of the H^(-)ions for neutral beam injection in nuclear fusion *** main design parameters of the ion source are:RF power ≤40 kW;extraction voltage ≤10kV;accelerator voltage ≤20 *** paper gives an overview of the progress of the ion source with particular emphasis on some *** RF driver and source plasma are analyzed and optimized in terms of impedance matching,plasma characteristics and power *** regard to the simulation analysis,a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion ***,a collisional radiative model of H and H2is built for plasma optical diagnosis.
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