Tetralin Hydrocracking Reaction Network to Single-Ring Aromatics on Bifunctional Catalysts

Conversion of LCO(light cycle oil)to BTX(benzene,toluene,and xylene)is an economically valuable method for refineries.However,this approach still faces difficulties as the main reactions are not clearly understood.Here we study the detailed hydrocracking pathway of typical reactants,1-methylnaphthalene and tetralin,through molecular simulations and experiments to improve our understanding of the conversion process of LCO to BTX.Molecular simulations demonstrate that the rate-determining step is the isomerization pathway of six-membered ring to five-membered ring in tetralin as its activation energy(ΔEa)is the highest among all the reactions and the order ofΔEa of reactions is isomerization>ring-opening≈side-chain cleavage.The results of experiments show that with the increase in reaction depth,i.e.,through a high temperature(350-370℃)and low LHSV(4.5-6.0 h^(−1)),isomerization,ring-opening,and side-chain cleavage reactions occurred,thus improving the selectivity and yield of alkyl aromatics.

Experimental investigation on chaos generation in erbium-doped fiber single-ring lasers

In this paper,the chaotic behaviors in an erbium-doped fiber（EDF） single-ring laser（EDFSRL） are investigated experimentally by using the loss modulation method.An electro-optic modulator（EOM） made of LiNbO 3 crystal is added to the system.Thus,by changing the modulation voltage and the modulation frequency of the EOM,the freedom of the EDFSRL system is increased.The chaotic characteristics of the system are studied by observing the time series and the power spectra.The experimental results indicate that the erbium-doped fiber single-ring laser system can enter into chaos states through period-doubling bifurcation and intermittency routes.

Adaptive VSG control of flywheel energy storage array for frequency support in microgrids

The application of virtual synchronous generator(VSG)control in flywheel energy storage systems(FESS)is an effective solution for addressing the challenges related to reduced inertia and inadequate power supply in microgrids.Considering the significant variations among individual units within a flywheel array and the poor frequency regulation performance under conventional control approaches,this paper proposes an adaptive VSG control strategy for a flywheel energy storage array(FESA).First,by leveraging the FESA model,a variable acceleration factor is integrated into the speed-balance control strategy to effectively achieve better state of charge(SOC)equalization across units.Furthermore,energy control with a dead zone is introduced to prevent SOC of the FESA from exceeding the limit.The dead zone parameter is designed based on the SOC warning intervals of the flywheel array to mitigate its impact on regular operation.In addition,VSG technology is applied for the grid-connected control of the FESA,and the damping characteristic of the VSG is decoupled from the primary frequency regulation through power differential feedback.This ensures optimal dynamic performance while reducing the need for frequent involvement in frequency regulation.Subsequently,a parameter design method is developed through a small-signal stability analysis.Consequently,considering the SOC of the FESA,an adaptive control strategy for the inertia damping and the P/ωdroop coefficient of the VSG control is proposed to optimize the grid support services of the FESA.Finally,the effectiveness of the proposed control methods is demonstrated through electromagnetic transient simulations using MATLAB/Simulink.

Microstructure and properties of 35 kg large aluminum alloy flywheel housing components formed by squeeze casting with local pressure compensation

The squeeze casting method with local pressure compensation was proposed to form a flywheel housing component with a weight of 35 kg.The numerical simulation,microstructure observation and phase characterization were performed,and the influence of local pressure compensation on feeding of thick-wall position,microstructure and mechanical properties of the formed components were discussed.Results show that the molten metal keeps a good fluidity and the filling is complete during the filling process.Although the solidification at thick-wall positions of the mounting ports is slow,the local pressure compensation effectively realizes the local forced feeding,significantly eliminating the shrinkage cavity defects.In the microstructure of AlSi9Mg alloy,α-Al primarily consists of fragmented dendrites and rosette grains,while eutectic Si predominantly comprises needles and short rods.The impact of local pressure compensation on strength is relatively minimal,yet its influence on elongation is considerable.Following local pressure compensation,the average elongation at the compensated areas is 9.18%,which represents a 44.90%higher than that before compensation.The average tensile strength is 209.1 MPa,and the average yield strength is 100.6 MPa.The local pressure compensation can significantly reduce or even eliminate the internal defects in the 35 kg large-weight components formed by squeeze casting.

双PWM变流器飞轮系统母线电压LADRC二次控制策略

提出一种基于二阶线性自抗扰控制(LADRC)的飞轮储能系统直流母线电压二次控制策略来应对飞轮储能系统频繁充放电切换带来的母线电压波动问题,其将母线电压及微分值分别视为状态变量,负载功率、参数不确定性等内外干扰视为扩展状态量进行扰动观测器设计。该策略能将工况切换造成电压波动的观测扰动量实时补偿至控制量中,实现扰动补偿。加入二次控制解决LADRC面对非常值扰动会存在稳态误差的问题,保证飞轮储能系统在充放能切换过程中母线电压具备较好的快速响应和抗干扰性能的同时实现无差控制。最后通过仿真验证了所提策略的有效性。

小样本下基于改进麻雀算法优化卷积神经网络的飞轮储能系统损耗

飞轮储能系统具有待机损耗,不适合长期储能。针对飞轮损耗这一经济指标,基于飞轮储能系统运行的小样本数据,提出了一种结合Logistic混沌麻雀优化算法和卷积神经网络的飞轮损耗计算模型。首先,分析了飞轮损耗产生的原因;接下来对宁夏灵武电厂的飞轮运行数据进行预处理,并使用对抗生成网络进行小样本扩充;然后基于卷积神经网络建立损耗模型,使用改进的麻雀算法对模型超参数进行优化,并通过对比验证了该模型的优越性;最后通过仿真实验证明了该模型能够优化飞轮储能系统的出力,降低飞轮损耗。

基础运动的储能飞轮转子动力学特性分析

针对基础运动的飞轮储能转子动力学问题展开研究,将飞轮转子等效为Timoshenko梁单元模型,通过坐标变换建立基础运动的转子动力学有限元模型,研究基础在规则运动时的动力学特性,得到以下结论:基础运动参数的增大会加剧固有频率分离并改变临界转速。转子稳态响应频谱中会出现基础运动的频率成分,幅值随基础运动频率、幅值的增大而增大;基础转动频率接近临界转速对应的频率时会产生共振,稳态频谱中基础运动频率成分出现峰值,瞬态升速响应出现额外共振峰。转子设计和应用时应考虑基础运动的影响。

飞轮储能辅助压缩空气储能一次调频仿真研究

压缩空气储能是一种优质的电网调节电源,其调峰能力较强而调频能力较弱,为缓解可再生能源发电大量接入所带来的频率问题,利用功率型飞轮储能辅助压缩空气储能机组运行,提高压缩空气储能机组的调频能力。给出了发电机组的简化频率计算模型、飞轮储能系统及压缩空气储能机组模型、区域电网频率控制模型,对不同飞轮容量配置模型组成的区域电网频率特性进行了仿真实验。结果表明:飞轮储能系统的加入提高了压缩空气储能机组的一次调频性能。

基于rLADRC的磁悬浮高速飞轮储能转子系统振动抑制

针对电磁轴承支承的高速飞轮储能转子系统振动抑制问题,提出一种降阶线性自抗扰控制(rLADRC)方法。首先,建立考虑陀螺效应及不平衡力的刚性飞轮转子系统径向四自由度二阶数学模型;其次,将各自由度数学模型中本自由度项作为内部扰动,其他自由度项带来的耦合和不平衡力项作为外界扰动,进而设计降阶线性扩张状态观测器(LESO)对总扰动进行实时估计;最后,设计线性状态误差反馈控制律(LSEF)并对总扰动进行补偿。结果表明:rLADRC能够实现转子径向四自由度之间的有效解耦,与传统分散比例积分微分(PID)控制和线性自抗扰控制相比,具有良好的动态性能和较强的扰动抑制能力,可在全转速范围内实现飞轮转子系统的稳定悬浮和对振动的有效抑制。

飞轮壳体黏弹性阻尼环的仿真分析与试验研究

随着航天器平台性能指标要求的提高,飞轮微振动对航天器平台的影响越加突出,需要对其进行振动抑制。根据飞轮上壳体的模态特性,提出一种圆环形黏弹性阻尼环结构的设计方法,并针对黏弹性阻尼环的敷设位置、厚度、宽度对其减振效果影响规律进行数值仿真与试验验证,验证圆环形黏弹性阻尼环的有效性。结果表明:圆环形黏弹性阻尼环结构对宽频振动具有良好的减振效果,黏弹性阻尼环的敷设位置对飞轮系统的各阶固有频率变化和减振效果起决定性作用,在飞轮外径的60%处敷设圆环形黏弹性阻尼环减振效果较好,宽度设计为飞轮外径的6%以内、厚度设计为壳体厚度的4倍以内时,随着宽度、厚度的增加,减振效果提高。

RESEARCH ON CONTROL OF FLYWHEEL SUSPENDED BY ACTIVE MAGNETIC BEARING SYSTEM WITH SIGNIFICANT GYROSCOPIC EFFECTS

Traditional PID controllers are no longer suitable formagnetic-bearing-supported high-speed flywheels with significant gyroscopic effects. Becausegyroscopic effects greatly influence the stability of the flywheel rotor, especially at highrotational speeds. Velocity cross feedback and displacement cross feedback are used to overcomeharmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects. A control platform based on RTLinut and a PCis built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, theflywheel successfully runs at over 20000 r/min.

基于深度强化学习的轨交飞轮储能系统能量管理

随着城市化进程的加速和公共交通系统的发展,地铁系统的运营效率和能源利用效率受到越来越多的关注。飞轮储能技术凭借其高功率循环能力,为轨道交通系统的能源利用问题提供新的解决方案。该文采用马尔科夫决策过程来描述单飞轮储能系统的能量管理问题,并使用基于深度Q网络的强化学习算法来学习最优的充放电阈值动态调整策略。通过在Matlab/Simulink平台搭建仿真环境,对开发的能量管理算法进行测试,并将其结果与固定充放电阈值、随机充放电阈值策略进行对比,表明该策略在提高电能利用效率和系统运行稳定性方面具有显著效果。

Spacecraft Attitude Tracking and Energy Storage Using Flywheels

The control law of the flywheel in an integrated power and attitude control system （IPACS） for a spacecraft is investigated. The flywheels are used as attitude control actuators as well as energy storage device. A feedback control law for attitude tracking is firstly developed by using Lyapunov approach, and then a torque based control law of the flywheel is studied. The control torque vector of the flywheel is decomposed into three parts which are orthogonal to one another by using the method of singularity value decomposition （SVD）. One part is used to provide the attitude control torque, another part is used to store energy with given power, and the last part is used to accomplish wheel speed equalization to avoid wheel saturation caused by large difference among the wheel spin rates. A management scheme for energy storage power using kinetic energy feedback is proposed to keep energy balance, which can avoid wheel saturation caused by superfluous energy. Numerical simulation results demonstrate the effectiveness of the control scheme.

Reducing Fuel Consumption Using Flywheel Battery Technology for Rubber Tyred Gantry Cranes in Container Terminals

Flywheel Energy Storage System (FESS) is used as an energy regeneration system to help with reducing peak power requirements on RTG cranes that are used to load or unload container ships. Nevertheless, with the use of FESS, Port Operator can deploy undersized generator for new RTG as this will further reduce fuel consumption. This paper presents the investigation of the amount of energy and fuel consumption that can be reduced in Rubber Tyred Gantry (RTG) cranes in container terminals by the use of simulation. In addition, Variable Speed Generator is integrated to the simulation-hybridized RTG. Simulation results reveal that the total energy saving exceeded 30% relatively to conventional RTG. A hardware-in-loop system is introduced for the purpose of validating the simulation results. The hardware components procured include a FESS, a Variable Frequency Drive (VFD) and brake resistors.

Integrated Power and Single Axis Attitude Control System with Two Flywheels

The existing research of the integrated power and attitude control system（IPACS） in satellites mainly focuses on the IPACS concept,which aims at solving the coupled problem between the attitude control and power tracking.In the IPACS,the configuration design of IPACS is usually not considered,and the coupled problem between two flywheels during the attitude control and energy storage has not been resolved.In this paper,an integrated power and single axis attitude control system using two counter rotating magnetically suspended flywheels mounted to an air table is designed.The control method of power and attitude control using flywheel is investigated and the coupling problem between energy storage and attitude control is resolved.A computer simulation of an integrated power and single axis attitude control system with two flywheels is performed,which consists of two counter rotating magnetically suspended flywheels mounted to an air rotary table.Both DC bus and a single axis attitude are the regulation goals.An attitude ＆ DC bus coordinator is put forward to separate DC bus regulation and attitude control problems.The simulation results of DC bus regulation and attitude control are presented respectively with a DC bus regulator and a simple PD attitude controller.The simulation results demonstrate that it is possible to integrate power and attitude control simultaneously for satellite using flywheels.The proposed research provides theory basis for design of the IPACS.

Flywheel Energy Storage with Mechanical Input-Output for Regenerative Braking

The system presented in this paper allows the direct transfer of kinetic energy of a vehicle’s motion to a flywheel and vice-versa. For braking, a cable winds onto a pulley geared to the vehicle’s propulsion driveshaft as it unwinds from another pulley geared to the flywheel and then operates in reverse for the transfer of energy in the opposite direction. The cable windings are in one plane resulting in an effective pulley radius that increases when the cable is winding onto it and decreases when unwinding from it. Thus, an increasing driven-to-driving pulley velocity ratio is obtained during a period of energy transfer in either direction. A dynamic analysis simulating the process was developed. Its application is illustrated with a numerical solution based on specific assumed values of system parameters.

Analysis of the Comprehensive Physical Field for a New Flywheel Energy Storage Motor/Generator on Ships

A novel flywheel energy storage （FES） motor/generator （M/G） was proposed for marine systems. The purpose was to improve the power quality of a marine power system （MPS） and strengthen the energy recycle. Two structures including the magnetic or non-magnetic inner-rotor were contrasted in the magnetostatic field by using finite element analysis （FEA）. By optimally designing the size parameters, the average speed of FEA results of was 17 200 r/m, and the current was controlled between 62 and 68 A in the transient field. The electrical machine electromagnetism design was further optimized by the FEA in the temperature field, to find the local overheating point under the normal operation condition and provide guidance for the cooling system. Finally, it can be concluded from the comprehensive physical field analysis that the novel redundant structure M/G can improve the efficiency of the M/G and maintain the stability of the MPS.

A Nonlinear Control Algorithm for Flywheel Energy Storage Systems in Discharging Mode

针对Buck-Boost变换器的非线性特征给飞轮储能系统的放电运行状态带来的控制问题,提出了电压电流双环非线性控制算法。基于输入/输出线性化理论,推导出电流内环的控制律,并证明了内动态的稳定性。电压外环采用鲁棒性强的滑模变结构控制方法,并增加限流环节,保证放电电路安全、稳定运行。在Matlab/Simulink仿真平台中搭建飞轮放电模型,对所提出非线性控制算法进行了仿真验证。仿真结果表明,相比于双环PI控制,该算法能够明显改善输出电压调节时间、超调量等动态特性,在输入电压存在大范围变化的情况下,输出电压能够保持恒定和较低的纹波系数。

Modular High-Power Electronics for a High-Speed MLC Flywheel Energy Storage System

The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vector-based hybrid pulse width modulation） for a reduced harmonic distortion and switching loss. Associated electromagnetic interference mitigation and cooling requirements are significantly reduced. Voltage source inverter drives a three-phase MLC200 flywheel. The modularity of the proposed topology also simplifies overall system design and manufacturability. The system topology and control strategy are discussed. Simulation results are presented to illustrate the harmonic distortion and switching loss reduction and reduced line current ripple.

THE CALCULATION METHOD OF FLYWHEEL MOMENT OFINERTIA OF CRANE MECHANISM

The origin and substance of the tlywheel moment calculation method of inertia mo ment of crane mechanism are set forth comprehensively and systematically in this paper, that is, the nucleus or the focus ofmoment of inertia calculation is the problem of calculating convertible tlywheelmoment. It is much better for the calculation of flywheel moment of loading move mass of lifting, traveling and rotating mechanism using the low of conservation of energy, the theorem of kinetic energyfor that of radius - changing mechanism, and the law of conservation of energy for that of all parts of gearing mechanism.