Utility experience with digital excitation systems

Ontario Hydro, a Canadian utility with an installed capacity of over 30000 MW, has utilized static excitation systems on a large number of generators, ranging from 3 MVA to 1100 MVA in size, since the early 1960's. Ontario Hydro has always attempted to take advantage of excitation system control as a means of eliminating or reducing stability constraints on their operation. The advent of digital excitation systems offered us the opportunity to work with manufacturers to incorporate special features or controls which had previously required complex additional hardware. This paper discusses the authors' experience with these systems, from 1988 to date, as well as providing a list of items which merit consideration by utilities and manufacturers as they move toward the second generation of digitally-implemented systems     

Utility URD cable experience

The large numbers of failures of primary underground residential distribution (URD) cables that utilities are experiencing is addressed. The major problems are defined and discussed and methods are suggested whereby the utility cable engineer could best find solutions. The problems and decisions fall into two general categories: those that concern existing in-service cables, and those that concern future URD cable designs. The discussion of existing cables covers cable replacement criteria, estimation of life remaining, cost-effective replacement methods, and concentric neutral corrosion. The discussion of future cables covers insulation selection, cable/conduit design, and life expectancy (the first two issues apply to replacement cables as well)     

Doing real time

The authors define real-time systems as those that are able to respond to specific events within a specific time. They examine the use of microprocessors in such systems. Time constraints that impact the design are discussed. They are the response time, survival time, recovery time, throughputs, and period of service request. Real-time techniques, i.e. software methods that reduce the execution time of part of the program, are considered. These reductions come at the expense of memory utilization     

Optimal real time pricing of real and reactive powers

This paper presents a theory and simulation results of real time pricing of real and reactive powers that maximizes social benefit. Conventional studies represented the responses of consumers as demand functions, and the objective of optimization was minimization of operating cost of power system. In this paper, the responses of consumers are represented as the inverse of the demand functions and power flow equations are incorporated in the constraints. This makes it possible to incorporate constant power factor demand consumer as a participant. That also makes it possible to maximize the objective function of optimization that is social benefit of participating in the electricity market and to determine the price of electricity at each bus. Not only the real time price of real power but also that of reactive power is determined simultaneously by the incorporation of power factor of loads into the constraint of optimization     

利用实时时钟X1203开启单片机系统

对于许多便携式数据记录系统,虽然系统大部分时间处于睡眠状态,但这样仍消耗一定的能量。为了进一步降低系统功耗,特设计一电源开关电路,可使单片机系统平时处于关闭状态,定时开启时系统上电,进行数据采集,一次工作结束时单片机关闭开关,系统断电。     

一种改进的组合实时自聚焦算法

在高分辨率SAR中,方位向运动误差给成像带来的影响越来越大,传统的相位梯度自聚焦(PGA)方法能够估计出运动误差,但其需要多次迭代计算,计算量大,不适合用于实时成像。为了满足高分辨率SAR实时成像的需求,提出了一种改进的组合实时PGA方法。这种方法将改进的频移相关算法(ISAC)算法、 PGA算法与RD成像算法结合运用,不仅使计算量大大减少,而且通过在频移相关算法中加入适量的迭代运算,降低了对运动初始参数的精度要求,取得了较好的成像效果。理论分析和实际数据处理证明了这种方法的有效性。     

实时人脸识别的一种快速算法

当前人脸识别的方向主要是针对静态人脸的单张图像识别,对个体采取多张照片采集,构成一个图片库,然后对捕捉的图像与图片库进行对比来进行人脸识别,鲜有对实时人脸的动态识别.本文提出了一种简单快速的实时人脸识别方法,采用对实时采集的灰度图像进行差分和积分投影处理,再进行极值判断和识别人脸.采用Visual c 对该算法进行编程实现,实验结果验证了算法的有效性.     

多通道数据实时采集标时系统设计

为适应某高炮靶场试验需要,设计了一种基于GPS守时的多通道数据采集标时系统,通过串口接收数据的同时为数据打上时间戳.系统通过多通道采集数据,支持RS232、RS422、RS485、光纤等多串口协议,且各通道波特率可分别设置;系统由GPS获得精确的秒级时间,毫秒级时间采用分频技术由内部定时器提供,并由GPS秒脉冲实时校正...     

基于GPU的多模式SAR实时成像算法研究

合成孔径雷达（SAR）成像处理需要较大的计算量,在基于中央处理器（CPU ）平台开发的SAR成像系统上处理一般需要消耗很长时间,无法满足实时成像的要求。借助于计算统一设备架构（CUDA ）编程模型,基于图形处理器（GPU ）提出了一种适用于多模式SAR的实时成像方案。该方案通过数据分段处理技术解决了计算设备GPU显存容量不足的问题;通过分析成像处理任务的并行度,利用异步执行流处理技术减少数据处理对数据交互的等待时间;通过优化GPU内存访问机制并使用特殊函数单元（SFU ）减少计算时钟周期。同时,该方案能够支持多GPU设备的并行处理,充分利用了GPU设备的计算资源。在NVIDIA GT 740M和INTEL Q6600上的实验结果表明,该方案与传统的基于CPU的单线程SAR成像技术相比,有了近150倍的速度提升,大大提高了SAR成像处理的计算效率,具有很好的工程应用前景。     

传感器输出时间序列实时预测方法的比较研究

为了提高传感器输出时间序列的实时预测精度,分析了时间序列可以预测的内在机理,认为噪声是影响预测精度的主要因素,提出了小波滤波与神经网络相结合的组合预测法,研究了最小二乘支持向量机的预测法,并选用了典型的过程变量信号,将两种方法进行了比较.仿真实验结果表明,小波滤波与神经网络相结合的组合预测法能够在消除测量噪声对预测精度...     

On power quality indices and real time measurement

Power quality (PQ) indices are used to quantify the quality of the power supply and serve as the basis for comparing the negative impacts of different disturbances on power networks. To overcome the limitations and deficiencies of the practical applications of some power quality indices in common use, a set of three new indices, namely the fundamental frequency deviation ratio (FDR), waveform distortion ratio (WDR), and symmetrical components deviation ratio (SDR) are proposed in this paper to summarize different types of power disturbances in a comprehensive manner. As instantaneous quantities, these novel indices can reveal the time varying characteristics of power disturbances in real time. Hence, the new PQ indices can well accommodate practical waveform distortions in power networks, which may be caused by multiple types of time varying power disturbances. They can therefore be further used to evaluate both the effectiveness and dynamic responses of PQ mitigation equipment in practical applications. To fully realize the advantages of the new PQ indices, a novel Atom (transform kernel) based time frequency transform and its recursive algorithm are also proposed as the supporting measurement technique. The new Atom approach can continuously measure the instantaneous frequencies and amplitudes of signal components in a nonstationary disturbance waveform with high accuracy, and then update the new PQ indices at each sample. The effectiveness of the new PQ indices and the supporting measurement technique were ascertained using various PQ events, both simulated events and those recorded at an industrial site.     

APF运行实时监控系统的设计

针对现有的有源滤波器APF(active power filter)存在数据存储量少、数据处理能力弱,远程监视能力差等问题,对APF运行中信号采集、处理、传送,显示等方面进行了研究,对实时运行监视系统的设计方法进行总结,设计了APF运行在线监测系统.该系统采用低功耗的STM32F103RBT6芯片作为信号采集处理控制器,利用STM32开发板外设的功能模块进行数据的传输、存储,并利用开发板标准通信接口实现了RS485远程通信,从根本上克服了APF数据存储量小及远程监测能力弱的问题.实验运行结果表明,此系统对APF数据的采集,处理的能力较于APF本身大为加强,数据存储量大幅度提升,远程监测效果好,并且该系统操作简单,成本低,具有较好的应用和推广价值.     

Development of a real time energy monitoring platform

This study introduces development of a user-friendly and quite effectual energy monitoring system which has been installed in Electrical Education Department of Gazi University in Turkey and in use since November 2007. The system developed monitors data in real time using a powerful energy analyzer which is capable of measuring many parameters of energy consumed in the building. The real time data measured by the power analyzer are transferred to a host computer via RS485 serial communication protocol and then collected in a database continuously. Thus, parameters of energy measured are successfully followed, archived, and presented as graphical forms.The monitoring system presented in the study integrates to quite visual and quite user friendly interface with powerful and flexible hardware. Therefore, several functions can be performed easily and safely by simple actions. On the other hand, the system presented in our paper is developed in a university, so it can be used by students to learn energy systems and parameters.     

实时检测系统设计

许多检测系统对采样速率的要求不是很高，但需要实时输出检测结果。本系统设计了采样控制电路，以使A／D转换自动进行。使用FIFO存储器作为A／D转换数据的缓冲存储器。在采满一定的数据量后FIFO存储器发出半满信号，计算机从FIFO存储器中读出数据并进行数据处理，输出处理结果。计算机从FIFO中读出数据和对数据的处理不影响A／D转换。     

矿井机车无人驾驶系统周期性消息实时性能研究

矿井机车无人驾驶系统在国内外尚未广泛使用,相关技术也不成熟,大巷内环境恶劣、人员复杂且劳动强度大、轨道路况差、信息化程度不高、运输调度多变等,要求系统具有高级别的可靠性、安全性、可信性等级。针对矿井机车无人驾驶系统中机车位置和机车信息等周期性消息传输的实时性问题,设计了基于时间有色Petri网的周期性消息实时性能建模与验证方法,对消息实时性能进行形式化建模与验证,通过模拟周期性AP切换和突发中断两类失效,经不同机车车速下丢包率和时延统计验证矿井机车无人驾驶系统周期性消息传递满足系统设计要求。     

远程实时堤坝边坡监测系统设计

针对堤坝远程监测有线传输方式信号失真、后期维护不便,以及部分无线通信技术开发难度大、成本高等问题,利用传感器多节点测量,结合RS485有线传输、2.4 G无线组网和GPRS网络,提出一种低成本、低功耗、易于开发的数据远程无线传输方案,实现高精度、大范围、全天候的堤坝边坡自动化监测.经测试,系统精度高、抗干扰性强,保持同一状态倾角传感器测量相对误差小于0.2％,温度传感器满足±3 ℃的精确度,湿度传感器满足±3％RH的测量精度,测试过程中无线组网稳定、远程数据传输可靠,监测界面直观明了.该系统在堤坝边坡稳定性和边坡防护检测方面具有实用价值.     

MPEG-4高级层实时编码器优化

MPEG-4高级层视频编码器(ASP)比目前普遍采用的简单层(SP)具有更优越的特性,但它的高复杂度使实时实现成为难点。利用TIC64xDSP的硬件结构和指令系统,提出了MPEG4高级层实时编码器各模块优化方法。在保证率失真性能基本不变的情况下,优化后的高级层编码器能够达到CIF格式的实时编码器要求。     

Educational aspects of CAD supported real time control

Educational aspects of CAD supported real time control are discussed. The historical development of the equipment and appropriate software concerning laboratory exercises in the field of real-time control is briefly described. The hardware and software equipment used in the education process at Ljubljana University is briefly described. Emphasis is given to the equipment developed: a hydraulic-thermal pilot plant, two CACSD program packages with their real-time capabilities, and a special program for real time control in addition to emphasizing their connection in a powerful educational system. Some typical exercises from undergraduate courses, e.g., some experiments on the connection of analog and digital computer, identification of the hydraulic process and its level control, as well as some exercises from a graduate course, e.g., the implementation of adaptive digital filtering in real-time are described. Some difficulties encountered when applying the theory to practical problems are discussed     

A real time testing system for wind turbine controller with xPC target machine

A cheap hardware-in-the-loop testing system for wind turbine controller is built based on MATLAB xPC. A wind-power generation model is constructed in the Matlab/Simulink of host machine, where the code is generated by real-time workshop and downloaded to the target machine. Then the virtual wind power generation system may be controlled by the physical controller, and the effectiveness and performance of the controller can be validated. By composing the drivers for xPC device, the selection of I/O devices for the testing system is flexible. A friendly interface of the testing system is established by combination of xPC and virtual reality toolbox. A testing system for wind power generation system with friend interface may be established by the described method.     

Efficient HVDC converter model for real time transients simulation

An efficient model has been developed to simulate high voltage direct current (HVDC) power converters in real-time transient simulators. Real time performance of 45 μs per solution step has been achieved for a 12-pulse monopolar converter and 81 μs for the bipolar converter using a single processor Pentium Pro 200 MHz desktop computer. The HVDC power converter model is solved simultaneously with the power network. Simultaneous solution makes the model capable of sustained long-time simulation for real time testing of system performance and control functions