In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy ...In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy storage system,the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor.At the same time,the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles.As a result,the size of battery is reduced,and the power quality of the hybrid energy storage system is optimized.Finally,the effectiveness of the proposed method is validated by simulation and experiment.展开更多
In order to explore the effect of loading rate on physical and mechanical properties of dihydrate gypsum,cyclic loading and unloading mechanical tests were carried out at different loading rates.Test results were anal...In order to explore the effect of loading rate on physical and mechanical properties of dihydrate gypsum,cyclic loading and unloading mechanical tests were carried out at different loading rates.Test results were analyzed from the aspects of stress-strain curve,energy distribution mode,damage law and failure mode of specimen.The main research results obtained in the thesis are as follows:with the increase of the loading rate,the peak value of specimen damage first increases rapidly,and then in-creases slowly,and there is a damage threshold.In the early stage of loading,the dissipated energy of the specimen accounts for about 70%of the total energy,most of the total energy input is converted into dissipated energy.The elastic energy density shows an increasing trend with the increase of the loading rate.The elastic energy density is the highest when the loading rate is 400 N/s,and more elastic energy can be stored.The ratio of elastic energy ue/u increases with the in-crease of loading rate and tends to be stable.The acoustic emission data show that the acoustic emission signals present a certain agglomeration phenomenon at the unloading point,and there is a“blank period”between the unloading point and the emergence of the next acoustic emission activity.In the early stage of specimen loading,friction-type acoustic emission is mainly generated.The cumulative ringing count when the load reaches the peak failure stress at low loading rate is more,indicating that low loading rate will produce more acoustic emission activities.With the increase of loading rate,the cumulative ringing number per unit time increases,indicating that the increase of loading rate accelerates the damage and failure of dihydrate gypsum near the peak value.The failure mode of gypsum specimens is shear failure,and the increase of loading rate of shear failure angle shows an increasing trend.The larger the loading rate is,the higher the strength of the specimen is.The more energy the press inputs during the loading process,the higher the ene展开更多
The variability of the output power of distributed renewable energy sources(DRESs)that originate from the fastchanging climatic conditions can negatively affect the grid stability.Therefore,grid operators have incorpo...The variability of the output power of distributed renewable energy sources(DRESs)that originate from the fastchanging climatic conditions can negatively affect the grid stability.Therefore,grid operators have incorporated ramp-rate limitations(RRLs)for the injected DRES power in the grid codes.As the DRES penetration levels increase,the mitigation of high-power ramps is no longer considered as a system support function but rather an ancillary service(AS).Energy storage systems(ESSs)coordinated by RR control algorithms are often applied to mitigate these power fluctuations.However,no unified definition of active power ramps,which is essential to treat the RRL as AS,currently exists.This paper assesses the various definitions for ramp-rate RR and proposes RRL method control for a central battery ESS(BESS)in distribution systems(DSs).The ultimate objective is to restrain high-power ramps at the distribution transformer level so that RRL can be traded as AS to the upstream transmission system(TS).The proposed control is based on the direct control of theΔP/Δt,which means that the control parameters are directly correlated with the RR requirements included in the grid codes.In addition,a novel method for restoring the state of charge(So C)within a specific range following a high ramp-up/down event is proposed.Finally,a parametric method for estimating the sizing of central BESSs(BESS sizing for short)is developed.The BESS sizing is determined by considering the RR requirements,the DRES units,and the load mix of the examined DS.The BESS sizing is directly related to the constant RR achieved using the proposed control.Finally,the proposed methodologies are validated through simulations in MATLAB/Simulink and laboratory tests in a commercially available BESS.展开更多
基金Supported by National Natural Science Foundation of China(Grant:51307009).
文摘In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles,a new hybrid energy storage system for electric vehicle is designed in this paper.For the hybrid energy storage system,the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor.At the same time,the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles.As a result,the size of battery is reduced,and the power quality of the hybrid energy storage system is optimized.Finally,the effectiveness of the proposed method is validated by simulation and experiment.
基金support from the National Natural Science Foundation of China,grant number 52174087.
文摘In order to explore the effect of loading rate on physical and mechanical properties of dihydrate gypsum,cyclic loading and unloading mechanical tests were carried out at different loading rates.Test results were analyzed from the aspects of stress-strain curve,energy distribution mode,damage law and failure mode of specimen.The main research results obtained in the thesis are as follows:with the increase of the loading rate,the peak value of specimen damage first increases rapidly,and then in-creases slowly,and there is a damage threshold.In the early stage of loading,the dissipated energy of the specimen accounts for about 70%of the total energy,most of the total energy input is converted into dissipated energy.The elastic energy density shows an increasing trend with the increase of the loading rate.The elastic energy density is the highest when the loading rate is 400 N/s,and more elastic energy can be stored.The ratio of elastic energy ue/u increases with the in-crease of loading rate and tends to be stable.The acoustic emission data show that the acoustic emission signals present a certain agglomeration phenomenon at the unloading point,and there is a“blank period”between the unloading point and the emergence of the next acoustic emission activity.In the early stage of specimen loading,friction-type acoustic emission is mainly generated.The cumulative ringing count when the load reaches the peak failure stress at low loading rate is more,indicating that low loading rate will produce more acoustic emission activities.With the increase of loading rate,the cumulative ringing number per unit time increases,indicating that the increase of loading rate accelerates the damage and failure of dihydrate gypsum near the peak value.The failure mode of gypsum specimens is shear failure,and the increase of loading rate of shear failure angle shows an increasing trend.The larger the loading rate is,the higher the strength of the specimen is.The more energy the press inputs during the loading process,the higher the ene
基金part of and supported by the European UnionHorizon 2020 project“EASY-RES”with G.A.:764090。
文摘The variability of the output power of distributed renewable energy sources(DRESs)that originate from the fastchanging climatic conditions can negatively affect the grid stability.Therefore,grid operators have incorporated ramp-rate limitations(RRLs)for the injected DRES power in the grid codes.As the DRES penetration levels increase,the mitigation of high-power ramps is no longer considered as a system support function but rather an ancillary service(AS).Energy storage systems(ESSs)coordinated by RR control algorithms are often applied to mitigate these power fluctuations.However,no unified definition of active power ramps,which is essential to treat the RRL as AS,currently exists.This paper assesses the various definitions for ramp-rate RR and proposes RRL method control for a central battery ESS(BESS)in distribution systems(DSs).The ultimate objective is to restrain high-power ramps at the distribution transformer level so that RRL can be traded as AS to the upstream transmission system(TS).The proposed control is based on the direct control of theΔP/Δt,which means that the control parameters are directly correlated with the RR requirements included in the grid codes.In addition,a novel method for restoring the state of charge(So C)within a specific range following a high ramp-up/down event is proposed.Finally,a parametric method for estimating the sizing of central BESSs(BESS sizing for short)is developed.The BESS sizing is determined by considering the RR requirements,the DRES units,and the load mix of the examined DS.The BESS sizing is directly related to the constant RR achieved using the proposed control.Finally,the proposed methodologies are validated through simulations in MATLAB/Simulink and laboratory tests in a commercially available BESS.
