基于潮流追踪的电网同步性能优化及鲁棒性分析

采用二阶类Kuramoto模型对电网进行合理建模,分别应用临界同步耦合强度和平均同步误差来描述电网的同步能力和鲁棒性.研究发现,发电机的功率分配对线路的传输功率影响较大,而电网中高负荷线路越多,网络越难同步.基于这一发现,首先在发电机功率均匀分配（EG）方式下,计算出每条线路的传输功率,然后基于潮流追踪算法提出一种发电机功率非均匀分配（TG）方式,即在发电总量不变的情况下,增大枢纽发电机节点的功率,减小边缘发电机节点的功率.该发电机功率分配策略可以在一定程度上降低网络的临界同步耦合强度,减小平均同步误差,改善电网的同步性能和鲁棒性.     

Transmitted power allocation/control for multi-band MC-CDMA

Transmit power allocation over multiple subcarriers is an effective way to improve system error probability performance and to save power in traditional multi-carrier systems. In this paper, we derive the optimum power allocation algorithm for multi-band MC-CDMA systems, where optimum is defined as minimal BER under the constraint of fixed transmitted power, assuming knowledge of power attenuation of different sub-bands. With a two-band MC-CDMA system and Rayleigh channel fading, we show that a BER performance improvement based on the optimum allocation can only be attained over a limited range of transmit power and a limited range of sub-band power attenuation difference values. This performance improvement is also modest compared with a uniform power allocation, which suggests that the uniform power allocation is near optimal for transmit power control under our assumptions. Two simple transmitted power control algorithms are provided, and the controlled transmit power for a two-band system is shown to be a linear function of the power attenuation difference between the two bands for a large range of these attenuation differences. The small non-linear range implies that in using a multi-band channel, any savings in total transmitted power can occur only when the power attenuation difference between the two bands is small.     

基于级联9电平技术的大功率超声波电源*

为了提高超声波电源的输出功率,该文提出了一种基于级联9电平技术的大功率超声波电源。电源逆变部分由两个H桥单元级联组成,经过一定的控制策略实现输出电压为9电平波形,可以显著提高超声波电源的输出功率,改善输出电压的波形质量。提出一种电压差法跟踪换能器的谐振频率,只需采样3个电压,根据3个电压之间的数值差调节输出频率。通过分析该超声波电源的系统结构、工作原理及控制策略,并进行仿真实验,验证了该方案的可行性和有效性。     

基于复杂网络的电网结构健壮性及Braess悖论现象研究

应用复杂网络理论,建立电力系统的改进导纳模型,结合电网拓扑特性和电气特性对电网的级联故障进行研究.通过随机移除传输线引发电网级联故障,研究网络的节点数、平均度、发电站数量以及发电站的分布状况对系统健壮性的影响,并对小世界电网级联故障过程中的布雷斯(Braess)悖论现象进行分析.研究表明:网络的健壮性与其拓扑结构密切相...     

用于Rb原子冷却系统的半导体激光放大(TPA)装置

报道了我们最近研制的780 13m半导体激光放大装置.激光放大管采用Eagleyard公司生产的(EYP-TPA-0780-01000)半导体锥形放大器,当输入的种子源激光功率为25 mW时,放大器输出的激光功率达600mW左右,该光束经过透镜整形,声光调制器频移,然后耦合到单模保偏光纤后,输出功率达110 mW.该激光放大装置可很好的用于高密度冷原子的俘获.     

High Power Pulsed Laser Power Supply Based on IGBT

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50W功率放大器的研制

介绍了一种L波段50W功率放大器的研制情况,采用功率合成技术获得了61W的输出功率,放大器增益大于40dB。给出了1W功放、10W功放和八路功率分配器的设计分析过程。     

基于复杂网络理论的互联电网Braess悖论现象分析

为了探究互联电力网络中的Braess悖论现象, 采用二阶类Kuramoto相振子模型对电网进行动力学建模, 将两个子网通过大度节点相连构建互联电网。当两个子网间有功率传输时, 分别在两个子网内部新增传输线路探究互联电网发生Braess悖论现象的概率并分析其原因。研究发现: 当互联电网中两个子网间的功率传输达到某一临界值时, 受电子网的同步能力远优于供电子网的同步能力, 供电子网新增传输线路引起互联电网发生Braess悖论的概率远高于受电子网新增传输线路引发的Braess悖论概率。通过定义子网序参数对上述现象的产生进行深入分析。本研究对互联电网的拓扑优化具有重要意义。     

Measurement of mechanical input power with an application to wall structures

This paper describes a simple method for measuring mechanical input power to a structure by direct analogue multiplication and integration of force and velocity signals. The influence of phase errors is controlled through measurement of both the real and the imaginary power components. The method is applied to some measurements on partition walls and agreement is obtained between input power and dissipated power computed from velocity and loss factor measurement on the wall surfaces.It is argued that the method is also applicable for a steady state measurement of the loss factor and, furthermore, that the power conversion efficiency, ζ, the ratio between the radiated sound power and input power, is a most relevant factor for characterising the radiation properties of mechanically excited partition walls.     

高功率横流CO2激光器大体积放电研究

详细讨论了脉冲预电离高功横流ＣＯ２激光器的工作特性，研究了一套新型的电极结构，对其放电，注入功率，输出功率等待进行了讨论。实验结果表明，脉冲预电离可以提高高功率横率流ＣＯ２激光器的注入和输出功率，并有效地改善了放电的稳定性和均匀性。     

A Novel Wavelength Division Multiplexing Passive Optical Network Based on Self-Seeding Light Source and Doubling Wavelength-Utilized Rate

Abstract

A wavelength-utilized rate-doubled wavelength division multiplexing passive optical network based on a self-seeding light source is proposed. The effect of distributed fiber length and power division ratio on the upstream-signal power is analyzed; the result indicates that raising the power division ratio can increase the upstream-signal power when it is lower than 0.86. The power difference between upstream signals caused by the length difference of distributed fibers is also expanded with power division ratio; thus, the power division ratio should be decreased to a proper level to reduce the power difference when the length difference is too large.     

一种新型电力网络局域世界演化模型

现实世界中的许多系统都可以用复杂网络来描述,电力系统是人类创造的最为复杂的网络系统之一.当前经典的网络模型与实际电力网络存在较大差异.从电力网络本身的演化机理入手,提出并研究了一种可以模拟电力网络演化规律的新型局域世界网络演化模型.理论分析表明该模型的度分布具有幂尾特性,且幂律指数在3—∞之间可调.最后通过对中国北方电网和美国西部电网的仿真以及和无标度网络、随机网络的对比,验证了该模型可以很好地反映电力网络的演化规律,并且进一步证实了电力网络既不是无标度网络,也不是完全的随机网络. 关键词： 电力网络 演化模型 局域世界 幂律分布     

紧凑型矩形波导内功率合成器设计

介绍了一种基于常规速调管功率合成和脉冲压缩的微波源系统,为实现多路高峰值功率速调管的功率合成,设计了一种紧凑型、近平面结构的微波功率合成器。在2.856 GHz频点处,合成器各端口反射损耗和相对端口隔离度均大于45 dB。当两路峰值功率为50 MW的微波功率合成时,合成器内的最大场强约为9.6 MV/m,合成效率大于99%。在四端口功率合成器的基础上,通过两级合成可实现一种八端口微波功率合成器,当四路峰值功率50 MW的微波功率合成时,合成器内最大场强约为13.5 MV/m。     

一体化光纤滤除器和端帽实现20 kW激光输出北大核心CSCD

在高功率光纤激光系统中,包层光滤除器能将光纤中包层光滤除以保证输出激光光束质量,光纤端帽通过对输出激光扩束降低输出光纤端面的光功率密度,从而保护光纤端面不受损坏,两者都是高功率光纤激光系统稳定运行的重要核心器件。将包层光滤除器和光纤端帽进行一体化设计,制备了一体化高功率光纤包层光滤除器和光纤端帽并分别应用于20 kW合束系统和单纤系统中,输出功率达到20 kW时,端帽的最高温度约为40℃,温升速率约为0.8℃/kW。     

Optimal Heat Exchanger Area Distribution and Low-Temperature Heat Sink Temperature for Power Optimization of an Endoreversible Space Carnot Cycle

Using finite-time thermodynamics, a model of an endoreversible Carnot cycle for a space power plant is established in this paper. The expressions of the cycle power output and thermal efficiency are derived. Using numerical calculations and taking the cycle power output as the optimization objective, the surface area distributions of three heat exchangers are optimized, and the maximum power output is obtained when the total heat transfer area of the three heat exchangers of the whole plant is fixed. Furthermore, the double-maximum power output is obtained by optimizing the temperature of a low-temperature heat sink. Finally, the influences of fixed plant parameters on the maximum power output performance are analyzed. The results show that there is an optimal temperature of the low-temperature heat sink and a couple of optimal area distributions that allow one to obtain the double-maximum power output. The results obtained have some guidelines for the design and optimization of actual space power plants.     

Simulation of Chromium Atom Deposition Pattern in a Gaussain Laser Standing Wave with Different Laser Power

One-dimensional deposition of a neutral chromium atomic beam focused by a near-resonant Gaussian standing- laser field is discussed by using a fourth-order Runge-Kutta type algorithm. The deposition pattern of neutral chromium atoms in a laser standing wave with different laser power is discussed and the simulation result shows that the full width at half maximum （FWHM） of a nanometer stripe is 115nm and the contrast is 2.5：1 with laser power 3.93mW; the FWHM is 0.8nm and the contrast is 27：1 with laser power 16mW, the optimal laser power; but with laser power increasing to 50mW, the nanometer structure forms multi-crests and the quality worsens quickly with increasing laser power.     

大功率激光单模光纤远距离传输的注入光纤光功率限值分析

对于大功率激光单模光纤远距离传输, 采用传统的受激拉曼散射(SRS)阈值作为注入光纤激光功率值取值过大。本文对单模光纤远距离传输过程中泵浦光和拉曼斯托克斯光(Stokes)光功率随注入光纤激光功率的变化进行仿真与理论分析。根据光纤中SRS产生的机理, 提出以拉曼Stokes光在单模光纤中传输的光功率变化曲线曲率极大值点对应的注入激光功率为限值, 对注入单模光纤光功率限值随着光纤长度变化进行仿真, 通过曲线拟合得出注入单模光纤激光功率限值公式, 并搭建实验系统进行验证。结果表明, 提出的注入单模光纤激光功率限值适用于大功率激光远距离单模光纤传输。     

频率自动跟踪超声波电源设计

针对超声波电源工作时负载状态改变,换能系统产生谐振漂移的问题,提出了一种基于STM32的频率自动跟踪超声波电源的设计。电源逆变电路采用带辅助网络的全桥结构,阻抗匹配电路选择了一种改进型的T型匹配网络,应用PWM移相调功技术控制电源的输出功率,通过数字鉴相技术得到电压电流的相位差作为电路谐振状态的反馈信号,结合STM32主控制器进行PI控制,调节PWM波的输出频率使电路始终工作于谐振状态,实现了谐振频率的自动跟踪。最后基于该设计方案,实际制作了一款应用于超声波清洗仪的电源,并通过实验验证了该电源具有输出功率稳定,负载适应性强,输出频率自动跟踪等特点。     

Microwave technology used to develop a solid state high power generator for ultrasonics

Conventional power generators for ultrasonic applications make use of design principles based upon audio and low frequency techniques. Using power combination technology originally developed for microwave and communication amplifiers, large amounts of power can be generated by combining the outputs of a number of low power transistors. The theory of hybrid transistor combining is explained and its application to ultrasonic power generators is illustrated. Matching an ultrasonic transducer to a transistor generator with the aid of a directional wattmeter is explained and a detailed example involving a piezoelectric transducer is given.     

一种紧凑型宽带高功率微波源设计与测试研究

设计了一款体积紧凑、工作在特高频波段的宽带高功率微波源,系统利用24 V蓄电池供电,Marx发生器作为驱动源,采用四分之一波长开关振荡器调制产生宽带电磁脉冲,激励高功率微带平板天线辐射,测试结果显示系统工作中心频率为425 MHz,远场辐射场强-距离积峰峰值为91.5 kV@1 m,该微波源体积尺寸为871 mm×370 mm×330 mm,含电池质量小于43 kg,拓展了宽带高功率微波技术在无人机、机器人等平台的应用前景。