Concurrent composite reliability evaluation using the state sampling approach

This paper presents a parallel methodology for composite reliability evaluation using Monte Carlo simulation by the state sampling approach. The methodology is based on coarse-grain parallelism, in which the adequacy analyses of the sampled system states are performed by different processors and the parallel process convergence is controlled by an asynchronous algorithm. The methodology was implemented on parallel and distributed processing environments: a ten-node IBM RS/6000 SP distributed memory parallel computer and a network of eight IBM RS/6000 43P workstations. The results obtained in tests with actual power system models show high speed-up and efficiency on both platforms and very good scalability.     

互感器二次压降及二次负荷模拟测试系统研究

互感器二次压降及二次负荷直接关系到电能计量的误差,是电力系统必须定期检定的项目。本文研制了一套用于电力技术人员培训用的模拟测试系统,采用三相电压电流源来模拟互感器的二次侧输出,用电阻、电抗序列模拟互感器的二次负荷及压降,接线方式包括三相三线制和三相四线制两种。以数字信号处理器(TMS320F206)为核心控制器,来控制各个模拟设备的参数,并通过A/D转换和运算放大等电路来采集电压、电流、功率因数等参数,整个系统由上位机软件进行控制,采用RS485串口通讯协议。实践表明该系统具有较好的稳定性和可靠性,模拟测试的各项指标符合现场测试的技术要求。     

基于Saber软件的数字控制电源系统的仿真设计

目前,在电源系统的设计中,计算机仿真已得到广泛的应用。由于数字控制电源的控制算法等均由数字处理器编程实现,而数字处理器的工作特点决定了数据处理过程是离散化的,因此设计出能够反应数字控制系统离散化特点的仿真模型,是数字控制电源系统仿真亟待解决的问题。本文在分析数字处理器的工作特点的基础上,提出一种适合于数字控制电源系统的建模仿真方法。由于该仿真模型非常贴近于实际的数字控制电源系统,因而可以用于数字系统的原理分析和参数整定等,所获得的参数对于控制系统设计具有重要的参考价值。     

A Simulation Study of Singular Value Decomposition for Controlled Plant Identification

A methodology is presented for the adaptive control of a single-input single-output system using the numerically stable method of singular value decomposition (SVD) for identification. This methodology is suitable for industrial applications where the plant parameters change slowly compared to the plant dynamics. A procedure is included for automatically identifying situations where the results of the identification are questionable. This procedure is based on three indices which are used to evaluate the identification. Expressions for computing these indices from the output of the SVD are derived. The identification procedure is numerically stable but computationally expensive. The computation time for identification may exceed the largest suitable sampling interval for some applications. To accommodate the long computation time, a parallel processing structure is used. In this structure, the identification is done as a background task in parallel with the controller function being performed by the processor. This structure permits use of the SVD method at low hardware cost for applications where the plant parameters are expected to change slowly. The feasibility of using an 8-b microprocessor to implement this methodology for adaptive control is demonstrated for a simulated plant of known structure and measurement noise characteristics. The identification time required is tabulated as a function of a) the number of parameters to be estimated, and b) the number of equations that are formed from the observed data.     

应用Matlab进行电力系统分析和动态仿真

Matlab中的电力系统模块PSB(Power System Blockset)是专门为电力系统设计的仿真分析软件,其功能十分强大。首先介绍了其中的模型,然后在仿真平台Simulink上利用PSB进行了励磁自动控制系统的设计和仿真、发电机并网的分析和动态过程仿真,得到了较满意的仿真结果。     

一种基于图形处理器加速的批量LU分解算法

潮流计算是电力系统计算的基础,其核心是LU分解计算,因此电力系统潮流计算加速的关键在于LU分解加速。当前,基于中央处理器(CPU)的并行算法已经成熟,性能提升空间有限。图形处理器(GPU)作为协处理器,在科学计算方面具有强大的优越性,被广泛应用到电力系统潮流计算中。文中首先分析了GPU结构和并行运行架构,然后介绍了LU分解原理,并选择了合适的矩阵排序算法和稀疏矩阵存储模型,借助统一计算设备架构(CUDA)编程模型实现了基于GPU的单个LU分解和批量LU分解并行加速,最后在仿真设备上测试了5个不同的案例,对比分析其并行算法的加速效果。仿真测试结果表明,基于GPU的批量稀疏LU分解并行算法,平均可以获得25～50倍的加速效果。     

A novel theory on parallel repeater‐insertion methodologies for long on‐chip interconnects

Repeaters are now widely used to enhance the performance of long on‐chip interconnects in CMOS devices. For RC‐as well as RLC‐modeled interconnects, parallel repeaters (PRs) have proved to be superior to serial ones. In a previous work, a new regeneration technique, named variable‐segment, was proven to outperform other existing regeneration techniques including variable‐repeater techniques. In this paper, an approximate analytical delay model is presented for both the variable‐repeater and variable‐segment parallel regeneration techniques. This model is used to confirm the optimality of our design and is built based on first and second‐moment transfer functions, which take into account the inductive effects of interconnects. HSpice electrical and C + +/MATLAB simulations are conducted to assess the performance of the proposed optimization methodology using 0.25‐µm CMOS technology. The mathematical simulation results are remarkably in agreement with those obtained from electrically simulated variable‐repeater and variable‐segment structures which are used in this work to regenerate interconnect lengths ranging from 0.1 to 10 cm. This work is part of a first‐of‐its‐kind global theory on PRs in repeater‐insertion methodologies for long on‐chip interconnects. This theory aims at exploring the different degrees of freedom in interconnect modeling as well as repeater type and design parameters. Copyright © 2011 John Wiley & Sons, Ltd.     

基于R-S-T控制的复合电源双向DC/DC变换器设计

为了提高复合电源双向DC/DC变换器工作过程中的动态特性,提出一种用于三通道交错并联双向Buck/Boost变换器的R-S-T控制策略。分析该变换器在Buck/Boost模态下工作过程,建立了交流小信号模型并得出控制变量到状态变量的传递函数,在此基础上设计了双向DC/DC变换器的R-S-T控制系统。相较于传统的PI控制,R-S-T控制策略具有更好的动态和稳态响应特性,最后运用Matlab/Simulink软件对该变换器系统进行仿真。结果表明,基于R-S-T控制的复合电源双向DC/DC变换器具有响应速度更快,超调量更小,鲁棒性更强的特点。     

An LSI-11 Microcomputer Laboratory

This paper summarizes the design, development, and implementation of an eight station microcomputer laboratory based on the DEC LSI-11 processor. The objectives and requirements of the facility are outlined as background for understanding the system design. Other sections are devoted to hardware, software, and courseware development for the laboratory. Hardware includes the LSI-11 processor, 16 channels of A-D input (eight channels differential), two channels of analog output, a minifloppy disk drive, a CRT terminal, and serial data links to an IBM 370 system. Software includes a custom-built monitor for the LSI-11, a cross assembler, simulator, linker, and down-line loader which run on the IBM 370, and special A-D and D-A routines. Courseware includes ten self-paced laboratory exercises, five real-time monitoring and control experiments, and a series of TV tape cassettes. Hardware plans, software listings, and class materials are available to interested readers by writing to the authors.     

微型水力发电机组系统建模与仿真

随着能源短缺现象的加剧,微型水力发电越来越被人们重视。研究了整个微型水力发电机组系统,首先分析了引水系统、水轮机和并联PID的数学模型;接着建立了相对应的仿真模型,励磁控制系统的模型,整个微型水力发电机组的模型;最后采用Matlab仿真软件,在动态负载条件下对该微型水力发电机组进行仿真,分析了负载和水头变化对机械功率、转子速度、电压和频率的影响。仿真结果表明,所建立的系统动态特性模型符合工程实际,满足系统的稳定性要求。     

用于NIOS II嵌入式处理器系统的鼠标控制器设计

Altera公司推出的NIOS II嵌入式处理器系统已经成为嵌入式设计的一个重要方向,但目前它的SOPCbuilder系统开发工具中并没有提供PS/2键盘和鼠标的IP核。为了适应部分嵌入式系统中要求用户操作方便的需要,本文详细介绍了一个用于NIOS II处理器系统的鼠标控制器的设计。本文依据Avalon从模式设备的接口规范和PS/2协议,设计了一个在NIOS II下支持标准PS/2(IBMPS/2)和微软的Intelli mouse规范的鼠标控制器。经实验验证,我们的设计有效的支持了标准PS/2(IBMPS/2)和微软的Intelli mouse模式。     

An object oriented perspective for AC/MTDC system simulation

Object oriented methodology (OOM) has added a new dimension for the representation, modeling and simulation of various day-to-day applications. The basic paradigm of OOM reflects the closeness to which the methodology relates to the real world entities. Over a period of time, the requirement of detailed and exact representation with no approximation of real world objects that reflects its behavioral pattern is on the rise. This has resulted in the terminology of ‘complex objects’ in system simulation. An AC-MTDC system has several interrelated/interconnected components and poses a complex picture. Objectifying such a system will improve the system design/analysis/identification/performance evaluation and control and provide a better understanding of the system in its entirety. In this paper a full representation of the various DC system sub-components is used for developing classes of components. A detailed representation along with the various attributes and methodologies associated with each of these components is given. The case study undertaken in this paper is a four terminal MTAC/DC system with all its terminal components. The paper highlights the various advantages the OOM technique offers for power system modeling. This notation is of immense help, especially during the system design stage wherein the tuning of various system components can be achieved without undergoing the rigor of conventional methods.     

基于FPGA的雷达天线方位角信号的模拟系统

为满足天线离线状态下的雷达测试需求,设计开发一种基于 FPGA 的雷达天线方位角信号的模拟系统。雷达天线方位角信号的模拟对雷达信号处理机性能的测试显得尤为重要,设计以伺服控制输出的 PWM信号、电机转动方向控制信号和制动信号作为输入参数,计算出雷达天线的方位角位置,并转换为光电编码传感器的脉冲信号输出给雷达信号处理机。该模拟系统具有输入输出信号属性与雷达天线单元一致、易实现等优点,并已应用于某型雷达测试系统,实践证明效果良好。     

An Assessment of the ECTS in Software Engineering: A Teaching Experience

Spain is currently implementing the regulatory modifications promulgated by the Declaration of Bologna, which should result in the updating of the structure of university degrees, and the inclusion of the European Credit Transfer and Accumulation System (ECTS) methodology. In some Spanish universities, the experimental adoption of this methodology has been encouraged, with the aim of gaining experience which could be extrapolated to other qualifications and subjects when this system becomes compulsory, which is expected to be in 2008. This paper examines the teaching methodologies that follow the experimental introduction of the ECTS in the Technical Software Engineering degree course taught at the Higher Technical College of the University of Cordoba, Spain. Based on data gathered in three specific subjects during the first and third years, this paper defines the teaching strategies implemented in order to increase the active role of students during their learning. The utility of e-learning tools in this type of teaching is discussed and the academic results are compared with results obtained in previous years using more traditional teaching methodologies.      

混合级联型直流输电系统直流故障特性及恢复控制策略

整流侧采用LCC、逆变侧采用MMC与LCC串联的混合级联型直流输电系统可实现直流故障穿越、换相失败抑制和大容量功率传输。建立混合级联型直流输电系统模型,设计系统整体控制策略,并利用PSCAD/EMTDC仿真软件研究系统功率阶跃时的动态特性,验证控制策略的有效性。对系统的直流故障特性进行仿真分析,发现若不采取合适措施,系统发生直流故障时会出现由于并联MMC之间的电流分配不均衡而产生过电流现象以及故障清除后系统恢复过程波动大的问题,为此,提出系统故障期间及故障清除后的恢复控制策略,仿真验证了该控制策略的有效性。     

基于AMBA-AHB总线多核平台的JPEG解码

随着半导体工艺技术的发展,在单一芯片上集成多个处理器核已成为可能,在高端应用需求的驱动下,片上多处理器系统（Multi—Processor System-On-a-Chip,MPSoC）为高度并行的计算和通信提供了一种可行的解决方案。本文首先描述了一种基于AMBAAHB层次总线结构的片上多处理器系统硬件架构,然后以此为基础实现了2种并行化的JPEG解码算法。实验采用Altera Stratix Ⅱ FPGA器件,整个系统运行在60MHz的时钟频率下,与采用单个处理器实现的串行JPEG解码算法相比较,在集成了4个处理器核的MPSoC系统架构上实现的并行JPEG解码算法得到的最大加速比为2．23。     

基于PSCAD/EMTDC的多端柔性直流输电系统并行仿真计算

对于基于模块化多电平换流器的多端柔性直流输电系统以及直流电网而言,传统基于串行结构的电磁暂态仿真软件已无法满足实际的计算需求,需要采用并行计算技术突破这一难题。PSCAD/EMTDC是世界上广泛使用的电力系统电磁暂态仿真软件,其最新版本已经全面支持并行计算。通过大模型拆分和多线程运算,该软件解决了由于模型过大而不能仿真或仿真效率低的问题,为实现多端柔性直流输电系统以及直流电网的快速仿真提供了可能。详细分析了PSCAD/EMTDC软件的运行机理及功能,对其新版本下的并行计算功能进行了介绍和研究。通过搭建模型进行仿真测试,探讨了并行计算的技巧。仿真结果表明,并行计算功能可以大大降低大规模电力系统的仿真时间,有效提升仿真分析效率。     

Comparison of Different Controllers and Stability Analysis for Photovoltaic Powered Buck-Boost DC-DC Converter

In this study, proportional integral (PI), fuzzy logic (FL), and sliding mode (SM) control of DC-DC buck-boost converter are presented. The obtained results were compared for these controller methods. The converter system, which is powered by photovoltaic (PV) modules, was simulated using the MATLAB/Simulink software. The sliding mode controller in which the inductance current and the output voltage are used as controller variables was tested and the results are compared with the results obtained by the fuzzy logic controller and proportional integral controller. The small signal analysis of the DC-DC buck boost converter has been conducted for the stability analysis of the designed system. Bode phase and magnitude diagrams are plotted for different duty ratios. The performance of the converter has been analyzed in detail for different photovoltaic conditions. The converter has been simulated for controllers and PV module using different parameters and the effects have been observed by the results. The converter experimental setup was implemented and the results were repeated. A digital signal processor (DSP) was used for the experimental study for faster processing. The experimental results were found to be compatible with the simulation results.     

泛在电力物联网中光伏发电系统常见故障研究

光伏发电作为泛在电力物联网能源生产端的新能源代表具有很广阔的发展前景。目前分布式光伏已得到大规模应用,以浙江为例,每年新增用户中绝大多数为低压配电网的用户。光伏发电系统由光伏组件串并而成,为了研究光伏系统中几种常见故障及其影响,按照国网低压光伏系统的参数要求搭建了仿真模型;并模拟了共4种常见故障状态下的光伏系统出力情况,仿真发现4种故障中即只有一片光伏电池片出现 4 类故障时,开路对输出功率的影响最大,其次是热斑,然后是短路,最后是老化。     

并联双绕组接触器电磁系统动态特性仿真分析

介绍了并联双绕组式交流接触器,并对其双绕组结构进行了理论分析。采用基于有限元方法的Maxwell3D软件对接触器电磁系统进行建模,仿真分析了电磁系统的动态特性。通过与试验数据的对比,验证了仿真方法的正确性。