On selecting transmission mode for D2D transmitter in underlay cellular network with a multi-antenna base station

The Device-to-Device(D2D)communication underlaying cellular networks is considered in this study.The D2D transmitter in the D2D mode can directly transmit messages to a receiver,but it may interfere with the transmission of another cellular user who shares the same uplink channel.The transmitter can also operate in a cellular mode in which no interference to another cellular user occurs.We propose a mode selection scheme that aims to minimize the transmission power of the D2D transmitter subject to constraints on the minimum required data rate and maximum interference to other cellular users.The proposed scheme is based on bounds for transmission power and is less complex than the optimal scheme.Furthermore,it requires only a few statistics and does not need a fading channel distribution.The performance of the scheme is close to optimum when the number of Base Station(BS)antennas is large,and the mean absolute deviation of the fading terms is small.We verify this with numerical results of the Rician and Rayleigh fading channels by assuming that the BS antennas are independent.The simulation results for the two correlated BS antennas are presented herein.

Study on Transmission Planning of Cascade Hydropower Stations along Lancang River Basin

Most of the hydropower projects in Southwest China and the adjacent foreign regions will be put into operation between 2015 and 2020, which will bring some difficulties for reasonable accommodation and delivery of electric energy. In this paper the author studies the development scale, development schedule, accommodation and transmission schemes of the cascade hydropower stations along the Lancang River basin, one of the five large basins in China, based on the load characteristics of grids at both the sending end and the receiving end, the strategy of complementary utilization of thermal power and hydropower, the advanced transmission technologies, and the optimal economic performance. The study results show that, the cascade hydropower stations on the upper reaches of the Lancang River in Yunnan should mainly serve Guangdong Province, with proper planning of partly serving Yunnan Province during dry seasons. The transmission schemes should adopt UHVDC, UHVAC, and single-tower double-circuited HVDC transmission scheme according to the transmission capacity and distance.

Design of intelligent detecting system based on wireless transmission

An intelligent detecting system based on wireless transmission is designed. Its hardware includes the card reading module, the wireless digital transmission module, the LCD module, the random password keyboard module and a 16×16 lattice word database based on e-Flash MM36SB020. Its software is a communication protocol between the central control computer and the entrance management base station. To resolve the conflicting problems occurred during the data transmission, a method of delaying time at random is proposed.

Introduction of 500 kV Three Corges-Changzou Electric Power Transmission Project

To transmit electric power from ThreeGorges to East China, ±500 kV HVDC willbe adopted. The first transmission Iine will beconstructed from the Longquan (Yichang)Converter Station to the Zhengping(Changzhou) Inverter Station. This projectconnects the East China Power Network withthe Central China Power Network,coordinates the hydro and thermal electricpower, obtains the profit from timedifference and promotes the process of theinterconnection of the power networks of thewhole country.This paper gives the abstract of thesituation of the preliminary design, primaryresult and development tendency of the firstHVDC transmission project which transmitsthe electric power from Three Gorges to EastChina.

Look Back Transmission Planning Around Three Gorges

In view of its huge installed capacity and very complex transmission system,the design process of China's Three Gorges Hydropower Station had been repeatedly demonstrated for more than ten years.The smooth construction,bringing into production and operation show that the planning scheme for Three Gorges power transmission project is successful.In this paper the design course of Three Gorges power transmission system is retrospected;the main planning schemes for Three Gorges power transmission system are reviewed;and the design results in different design stages are summarized.

A Hybrid Algorithm for Satellite Data Transmission Schedule Based on Genetic Algorithm

A hybrid scheduling algorithm based on genetic algorithm is proposed in this paper for reconnaissance satellite data transmission.At first,based on description of satellite data transmission request,satellite data transmission task model and satellite data transmission scheduling problem model are established.Secondly,the conflicts in scheduling are discussed.According to the meaning of possible conflict,the method to divide possible conflict task set is given.Thirdly,a hybrid algorithm which consists of genetic algorithm and heuristic information is presented.The heuristic information comes from two concepts,conflict degree and conflict number.Finally,an example shows the algorithm's feasibility and performance better than other traditional

Simulation of natural gas transmission pipeline network system performance

Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.

天气雷达站电磁环境影响监测研究

天气雷达站产生的超标电磁辐射会对人体造成严重的损伤。为此,提出天气雷达站电磁环境影响监测与分析。分析天气雷达站电磁影响因素,结合发射天线的方向函数,构建雷达功率密度模型。测试结果表明,对于S波、C波段、X波段,真实值与计算值呈现随距离增加而降低的趋势。对于三个波的频段,当接近天线的远场区时,计算值与真实值逐渐接近,相对误差均较小,说明模型在远场区的适用性更强;研究算法与实测值的拟合程度较高;在模型的应用中,真实反映了某市区的电磁辐射情况。

长距离输水泵站中空气罐参数敏感度分析及正交优化设计

为了探讨长距离输水泵站中空气罐的优化设计方法,以西北某长距离输水工程为例,以泵站水击最大正压水头和最小负压水头作为优化目标,以初始气体压力、高度直径比、连接管直径、进口阻力系数和出口阻力系数为优化变量,基于正交优化设计方法和KYPipe软件,采用极差分析法获得空气罐各参数对于水击最大正压水头和最小负压水头的影响,同时对得到的结果进行排序,比较并找到最优参数组合.结果表明:初始气体压力、连接管直径和出口阻力系数等因素对于水击最大正压水头和最小负压水头的影响程度较大,其中初始气体压力是最敏感的参数,对于最大正压水头和最小负压水头的影响程度最大;经过比较发现最优方案的参数组合为初始气体压力水头50 m、高度直径比4、连接管直径250 mm、进口阻力系数10、出口阻力系数5;相比原始方案,优化方案使泵站的水击最大正压水头降低4.98%、最小负压水头升高64.00%.

断路器选相投切系统在换流站中的应用研究

在换流站滤波器组及换流变压器配置断路器选相投切系统,可改善断路器开合暂态过程,在取消合闸电阻工况下仍可避免对电力设备及系统造成冲击。基于多个换流站选相投切工程实施及调试经验,进行了换流站选相投切系统应用的调查。介绍了选相投切系统构成、选相投切要求、断路器配套及预测试方法等。重点针对滤波器组、换流变压器的选相投切应用,总结了控制策略、选相投切系统带电冲击试验,及工程使用中需重点关注的问题、设备运维要求等,为相关技术人员提供参考。试点工程在特高压断路器中创新性地采用取消合闸电阻、增设选相合闸的专项改造方案。断路器选相投切系统总体运行效果良好,为技术的推广积累了工程运行经验。

基于系统论事故分析模型的油气智慧管道系统信息物理风险辨识

为了辨识油气智慧管道系统中存在的信息安全风险,通过基于系统论事故分析模型(systems-theoretic accident modeling and process,STAMP)的方法,对油气智慧管道系统的信息物理安全进行全面评估与分析。首先,系统综合分析了油气智慧管道涉及的设备、设施、工艺、元件,评估其安全性。其次,通过建立STAMP模型,深入分析了各层级、元件之间的反馈信息与控制动作,形成了明确的控制反馈回路,突显了元件之间的关联与控制关系。在此基础上,系统辨识出了潜在的信息风险因素,推导并构建了可能发生的系统失效场景。以天然气输气首站油气智慧管道系统为例,研究验证了基于STAMP模型的可行性和有效性。结果显示,该方法不仅直观地描述了元件之间的关联与控制关系,而且从物理层功能安全的角度全面考虑了信息风险,特别凸显了过程控制系统(process control systems,PCS)及易受攻击的操作员站。与传统方法相比,本研究所提出的方法将信息物理安全风险因素的识别率提升至80%以上,提高了40%以上,有助于避免不必要的安全措施冗余设计,提高了安全风险管控的准确性。

基于超导磁储能的光伏场站送出线路距离保护

受光伏逆变器控制策略影响,光伏场站呈弱馈性和电流相位受控特性,导致送出线路光伏侧距离保护的测量阻抗无法正确反映故障所在位置,抗过渡电阻能力大大下降。根据送出线路系统的故障分量序网图推导出线路短路阻抗的求解方程组,同时基于光伏场站直流母线接入的超导磁储能(superconducting magnetic energy storage,SMES)改变传统的低电压穿越控制策略,通过控保协同消除方程组中的未知量,进而对线路短路阻抗进行求解,提出了基于超导磁储能的光伏场站送出线路距离保护方案。与现有推导线路短路阻抗的方法相比,该方法不存在近似计算,计算准确度得到很大提升;且相比于其他控保协同方案,该方案在保证距离保护可靠动作的同时也兼顾了故障期间光伏场站对于电网的无功支撑,其低电压穿越能力不仅没有被削弱,反而得到一定的提升。

输油气站场工控系统网络安全防护探讨

本文围绕输油气站场工控系统的网络安全防护需求,基于美国国家标准与技术研究所(NIST)的网络安全框架,研究探讨了输油气站场工控系统的网络安全防护措施与建议,以期为输油气站场工控系统运营者开展网络安全管理工作提供参考依据。

武器站伺服传动装置在线辨识与自适应控制方法

针对武器站俯仰轴伺服传动装置在武器载荷变化时控制精度和安全性下降的问题,提出基于多参数在线辨识的自适应复合控制方法。基于符号函数的线性化方法,构建包含传动间隙、电机和负载摩擦非线性的伺服传动装置待辨识模型框架,推导出待辨识参数的显式迭代方程,通过带遗忘因子的递推增广最小二乘算法实现参数在线辨识。在此基础上,提出自适应比例积分控制器与自适应状态扩张卡尔曼滤波器相结合的复合控制方法。实验结果表明:参数辨识方法可实现伺服传动装置9个关键动力学参数的精确在线辨识,稳态辨识误差不超过10%。自适应复合控制方法将系统速度跟随残差均方根降低了28.24%,有效提升了俯仰轴在武器载荷变化时的控制精度和稳定裕度。

基于动态平衡布局的输电网潮流图自动生成方法

为解决输电网潮流图自动生成中厂站布局与线路布线问题,提出基于动态平衡布局的输电网潮流图自动生成方法。针对厂站布局,首先,在力导向算法的基础上引入基于图纸中心点的惩罚函数,以解决力导向算法布局不均匀的问题,提高布局的均布度;然后,利用厂站分布率参数控制算法平衡次数,引导厂站向图纸边界运动,解决布局自动适应给定图幅大小的问题;最后,通过位置映射变换将围绕图纸中心点的椭圆分布转换为矩形分布,解决引入惩罚函数布局均匀但不符合传统输电网潮流图绘制习惯的问题。针对线路布线提出以构建通道树为中心的布线方法,有效降低布线交点个数,提升布线效果。所提布局与布线算法在实际工程应用中取得了良好的效果,通过案例验证了输电网潮流图自动生成的正确性和有效性。

三线平行地铁车站振动及传播规律实测研究

【目的】研究三线平行地铁进出站引起的地铁车站的振动特性。【方法】以国内某城市三线平行换乘地铁车站为研究对象,基于现场实测数据分析该车站振动特性及传播规律。【结果】受线路建成及运营影响,该车站内各站台振动响应差异较大,进站工况下,站台1,站台2和C线站台平均Z振级分别为81.9,91.4,61.7 dB;站台1和站台2振动主要频段为75~125 Hz。出站工况下,3个站台的平均Z振级分别为82.7,93.8,63.7 dB;站台1和站台2的振动主要频段为50~100 Hz。C线站台振动响应在两种工况下均集中在50~60 Hz内。【结论】在车站内多数测点均可发现出站工况下振动大于进站工况,最大差值约2.5 d B。车致振动传递至地面一层后会先产生一定衰减,传递至地面二层时则会产生放大,振动放大约3.6~5 dB。车致振动在该车站建筑内的传递所产生的衰减较小,振动衰减主要依靠的是土层,振动衰减量约为0.53 d B/m。研究成果可为类似结构、平行接入多条线路的地铁车站及车站上盖建筑的振动预测、振动舒适度评价及减振设计提供参考依据。

山地城市交通场站空间布局方法与重庆实践

基于对山地城市交通场站空间布局难点的分析,从适应各级国土空间规划编制需求的视角总结交通场站规划编制及管控工作的重点任务,从管控单元、评估度量方法、管控指标体系、动态调整机制4个维度阐述山地城市交通场站专项规划编制的思维变革,结合重庆中心城区公交场站布局规划的实证探索,构建适应国土空间规划传导体系的交通场站专项规划编制方法。在管控单元划定上,逐步向以服务单元为单位的差异化管理方式转型,分类明确管控方向;在评估度量方法上,叠合公交车实际行驶路径与泰森多边形面域,划定服务范围;在管控指标体系构建上,实现管控指标与人口、用地及设施布局的多维契合;在动态调整机制上,建立“刚弹结合”的动态调整机制,灵活应对用地布局调整的不确定性。

兼顾本地与直流受端电网调峰需求的水电站群短期优化调度模型

面对巨型水电站群高压直流送端电网和受端电网日益严峻的调峰压力,建立了一种兼顾本地与直流受端电网调峰需求的梯级水电站群短期优化调度模型。模型以多电网剩余负荷最大值最小为目标,考虑常规梯级水电站群水力、电力约束,以及复杂高压直流输电线路运行约束,并引入直流线路与水电站之间耦合运行约束。在模型求解阶段,引入辅助变量将目标函数、水电运行约束、直流运行约束线性化,并采用大M法对直流线路与水电站之间双向区间耦合约束进行线性化,将原模型转换为混合整数线性规划模型。以中国西南地区某巨型水电站群冬季和夏季典型日为实例研究,结果表明:送端电网负荷峰谷差降幅高达100%,受端电网负荷峰谷差降幅分别达28.1%和31.6%。所提模型能够利用高压直流输电线路共享水电灵活性,有效实现多电网调峰,并保证直流输电线路运行在安全区间,可以为巨型梯级水电站群短期多电网调峰提供参考和借鉴。

2 GW海上风电对称单极与对称双极柔直送出方案技术经济性对比

现阶段海上大容量风电接入电网通常采用柔性直流输电技术,目前已投运的海上直流工程均采用对称单极接线方案。对称双极方案虽然初期投资高,但其高可靠性可以提高运行阶段的发电盈利。基于2 GW海上风电柔性直流送出规模,开展了对称单极和对称双极系统的设计对比,提出了两种接线拓扑对应的海上换流站平台布置及结构设计方案,并对两种方案的初期建设投资及全寿命周期盈利进行了计算。结果表明对称单极方案较对称双极方案在全生命周期经济性上具有优势。