课程文献中心 更多>>

关键词： 域控制器   CEV   Ansys仿真  

摘要： 从域控制器大电流型PWM输出遇到的CEV问题切入,对其根本原因进行理论分析,提出了针对此类问题的解决方案,并利用Ansys_SIwave软件对方案进行仿真,通过比对仿真结果找到最优方式。最后,依据仿真最优配置进行硬件电路调整并实测,实测结果与仿真结果具有较好的一致性,验证了相应解决措施对解决域控制器大功率PWM输出CEV超标问题的有效性。

关键词： 弱电网   电压越限   储能型MMC-RPC   跟网型和构网型控制   三维度控制   能量管理  

摘要： 针对弱电网条件下,牵引网压越限导致的机车不能正常运行问题,采用一种储能型(Energy storage,ES)模块化多电平(Modular multilevel converter,MMC)的铁路功率调节器(Railway power conditioner,RPC),即ES-MMC-RPC,来抑制网压越限。较传统的系统扩容、电容器组的无功补偿电压治理方案,在分区所加装了ES-MMC-RPC,较传统的跟网型电流补偿控制,装置采用了动态性能更好的构网型或三维度支撑控制进行两侧供电臂的功率平衡;装置中的储能也采用了构网型控制,以进一步支撑电压。最后,提出在弱牵引网条件下ES-MMC-RPC装置的三层能量管理策略,通过有功平衡、装置自身及储能的功率支撑对网压进行三重支撑。经仿真验证,改进的构网型控制的ES-MMC-RPC能确保弱电网地区的牵引网压的稳定。

关键词： African vulture optimization algorithm(AVOA)   least squares support vector machine(LSSVM)   variational mode decomposition(VMD)   multi-objective prediction   wind power  

摘要： Improving the prediction accuracy of wind power is an effective means to reduce the impact of wind power on power ***,we proposed an improved African vulture optimization algorithm(AVOA)to realize the prediction model of multi-objective optimization least squares support vector machine(LSSVM).Firstly,the original wind power time series was decomposed into a certain number of intrinsic modal components(IMFs)using variational modal decomposition(VMD).Secondly,random numbers in population initialization were replaced by Tent chaotic mapping,multi-objective LSSVM optimization was introduced by AVOA improved by elitist non-dominated sorting and crowding operator,and then each component was ***,Tent multi-objective AVOA-LSSVM(TMOALSSVM)method was used to sum each component to obtain the final prediction *** simulation results show that the improved AVOA based on Tent chaotic mapping,the improved non-dominated sorting algorithm with elite strategy,and the improved crowding operator are the optimal models for single-objective and multi-objective *** them,TMOALSSVM model has the smallest average error of stroke power values in four seasons,which are 0.0694,0.0545 and 0.0211,*** average value of DS statistics in the four seasons is 0.9902,and the statistical value is the *** proposed model effectively predicts four seasons of wind power values on lateral and longitudinal precision,and faster and more accurately finds the optimal solution on the current solution space sets,which proves that the method has a certain scientific significance in the development of wind power prediction technology.

关键词： 加州鲈   高效养殖   大口黑鲈   摄食习性   示范推广   技术关键点   驯化   探讨与实践  

摘要： 加州鲈鱼苗的驯化成功率是一个复杂的过程,涉及到鱼苗的摄食习性、饵料选择、投喂策略等多个方面,笔者结合开展的《大口黑鲈鱼苗驯化及高效养殖模式技术示范推广》项目试验示范推广数据,总结了如何提高加州鲈鱼苗驯化成功率的几点技术关键点供大家探讨。

关键词： Sub-100 nm DG-MOSFET   gate-oxide dielectric   high-frequency   inverter   metal work function  

摘要： This paper presents simulation analysis of an inverter made from non-aligned double gate field effect transistors (NADGFETs) in Sub-100 nm regime. The inverter consists of n-channel NADGFET and p-channel NADGFET device with a channel length of 40 nm and 50% non-alignment between gate and source/drain. The response of the inverter was tested by a combination of gate dielectric constant (k) and metal work function (phi). Three gate dielectrics namely, SiO2 (k = 3.9), Si3N4 (k = 7.2), HfO2 (k = 24), and three metal work function namely tungsten (phi = 4.5 eV), molybdenum (phi = 4.75 eV), gold (phi = 5 eV), were considered in the NADGFET inverter. This paper defines a k phi index as characterising parameter to explore the best response from inverter configuration with minimum propagation delay, and minimum power consumption at super-high frequency. The paper proposes to analyse the NADGNFET device, in term of ION current, ION/IOFF ratio, cut-off frequency, and gate delay. And observes that low k material with moderate metal work function gives best response. The work then simulates the inverter and group the results into voltage transfer curve (VTC), transient response, and power dissipation category. The result shows that when inverter was subjected to high frequency, all the k phi combination responds good, however when the inverter was subjected to super-high frequency, the low value of k phi combination performs well. Thus, the result concludes that SiO2-M-2 combination will be best selection to get minimum propagation delay and dynamic power dissipation by the inverter. The test strategy presented in this paper on the basis of k phi index can serve as benchmark to test inverter device at super-high frequency.

关键词： 无功控制   交流母线电压   绝对最小滤波器限制   逆变站  

摘要： 梳理牛从高压直流输电系统双回直流协调控制中无功控制优先等级及其逻辑,结合仿真和现场工程实际情况证明交流母线电压投切无功补偿设备优先于绝对最小滤波器容量限制的原因。同时,对比牛从高压直流输电系统直流与新东特高压直流输电系统直流绝对最小滤波器容量限制直流功率策略,并提出优化建议。

关键词： 功率循环寿命   SiCMOSFET分立器件   环氧树脂   高温存储   玻璃化转变温度  

摘要： 分立器件主要使用环氧树脂封装材料以保护芯片免受机械损伤和环境腐蚀,但环氧树脂材料的热稳定性较差,在高温环境下易发生化学反应,影响器件的性能。因此,一般要求器件的工作温度不能超过环氧树脂的玻璃化转变温度。以SiCMOSFET分立器件为研究对象,通过功率循环试验深入探究高温存储对器件功率循环寿命的影响。结果表明,经高温存储后器件的寿命得到显著提升。此外,通过对高温存储前后环氧树脂材料进行热机械分析,发现环氧树脂材料的热稳定性经高温存储后得到增强。最后,通过建立有限元仿真模型,深入分析高温存储对器件芯片表面应变及键合线应变的影响,发现高温存储后器件芯片表面应变及键合线应变变小,解释了高温存储对器件寿命提升的影响机理。

关键词： 大型变压器   故障检测   故障诊断   多传感器信息融合   电力系统稳定性  

摘要： 大型变压器作为电网核心设备,其稳定运行是电力系统可靠供电的基石。面对设备老化带来的挑战,本研究聚焦于大型变压器的故障检测与诊断。采用多传感器信息融合、大数据技术和人工智能方法,实现对变压器健康状态的实时监控与智能诊断。研究结果显示,该技术显著提高了故障预警的准确性和故障诊断的效率,为电力系统的稳定运行提供了有力保障。此外,通过业务应用实践,发现该技术不仅可以大大降低设备因故障而产生的维护成本,同时也可以提高电力系统的运行稳定性和可靠性,对保障国家电力供应安全具有重要的理论和实践意义。

关键词： 变压器故障   异常运行   交变电流   变压器安全   系统故障   交变磁场   异常声音   判断故障  

摘要： 如果在日常变压器的运行中听到一些异常的响声,这些都是变压器异常运行的先兆。只有通过变压器异常声音的分析,正确判断出是变压器故障或者是系统故障,然后经过正确处理,才能保证该变压器安全运行。1变压器的正常运行声音变压器在交变磁场的作用下,运行中的声音是轻松、均匀的“嗡嗡”声,声音中没有任何杂音,是连续、一致的交变电流的声音,虽然比不上优美的音乐那样入耳,但也不是刺耳的声音。

关键词： 变电一次检修   断路器   隔离开关   变压器  

摘要： 阐述针对变电一次检修运行中的断路器、隔离开关、变压器问题,从优化检修方案、采用先进技术规范化管理、强化对检修人员培训方面,提出具体的解决策略。