考虑量测错误和多源异质信息融合的变电站概率故障诊断:统一的Bayes网络模型

故障诊断对提升电网故障分析处理能力有重要意义。在变电站本地进行故障诊断可以更加充分、敏捷地利用本地的丰富信息。为适应智能电网环境下信息丰富、分布自治的趋势,提出一种基于Bayes网络的变电站故障诊断方法,考虑了保护、开关的拒误动和量测信道错误等不确定性,并综合利用顺序事件(sequence of events,SOE)、故障录波、保护闭锁等多源异质信息。使用经典的联结树(junction tree)算法进行概率推理。结果表明:与不考虑量测信道不确定性的方法相比,该方法可以更加充分利用开关SOE等信息;故障录波和闭锁等非SOE信息的引入可以有效提升诊断的准确率。

状态估计研究模式设计及应用

由于实际电力系统运行工况复杂,状态估计无法避免出现不收敛的情况,反演时难以再现断面结果,在对量测方式和参数进行调整时会造成合格率指标波动,同时也会影响实时网络分析应用系统的稳定运行。分析现有状态估计运行中存在的问题及应用需求,设计实现了状态估计研究模式分析平台。首先,通过断面管理和读取功能保存状态估计计算所需的全部信息;然后,通过研究模式反演,实现断面读取、分析调试计算;最后,通过分析对比功能,为参数和量测调整提供指标参考。上述工作使得状态估计计算结果完整再现,并且分析过程独立于实时状态估计因而不影响实时合格率,自动化专业人员可以依据分析对比功能提供的指标对量测和参数问题有目标地进行分析。通过华北分中心的实际使用,证明平台功能可满足专业人员对状态估计的分析调试需求。

Improved metrics for evaluating fault detection efficiency of test suite

By analyzing the average percent of faults detected （APFD） metric and its variant versions, which are widely utilized as metrics to evaluate the fault detection efficiency of the test suite, this paper points out some limitations of the APFD series metrics. These limitations include APFD series metrics having inaccurate physical explanations and being unable to precisely describe the process of fault detection. To avoid the limitations of existing metrics, this paper proposes two improved metrics for evaluating fault detection efficiency of a test suite, including relative-APFD and relative-APFDc. The proposed metrics refer to both the speed of fault detection and the constraint of the testing source. The case study shows that the two proposed metrics can provide much more precise descriptions of the fault detection process and the fault detection efficiency of the test suite.

Orthogonality of inductosyn angle-measuring system error and error-separating technology

Round inductosyn is widely used in inertial navigation test equipment, and its accuracy has significant effect on the general accuracy of the equipment. Four main errors of round inductosyn,i.e. the first-order long-period (360°) harmonic error, the second-order long-period harmonic error, the first-order short-period harmonic error and the second-order short-period harmonic error, are described, and the orthogonality of these four kinds of errors is studied. An error separating technology is proposed to separate these four kinds of errors, and in the process of separating the short-period harmonic errors, the arrangement in the order of decimal part of the angle pitch number can be omitted. The effectiveness of the technology proposed is proved through measuring and adjusting the angular errors.

High Accuracy On-line Measurement Method of Motion Error on Machine Tools Straight-going Parts

Harmonic suppression, non-periodic and non-closing in straightness profile error that will bring about harmonic component distortion in measurement result are analyzed. The countermeasure-a novel accurate two-probe method in time domain is put forward to measure straight-going component motion error in machine tools based on the frequency domain 3-point method after symmetrical continuation of probes' primitive signal. Both straight-going component motion error in machine tools and the profile error in workpiece that is manufactured on this machine can be measured at the same time. The information is available to diagnose the fault origin of machine tools. The analysis result is proved to be correct by the experiment.

Allowance of Lateral Breakthrough Error for Super Long Tunnels from 20km to 50km

Up to now there is no specification about the allowance of lateral breakthrough error for super long tunnel from 20 km to 50 km. On the basis of the design of GPS networks located outside and inside tunnel traverse network, we propose a method for calculating the influence value caused by control surveying errors. Through a lot of simulative calculations and combination with piercing practice of super tunnels in Wan Jiazai Project, Shanxi province, we present an allowance table of lateral breakthrough error for super long tunnels from 20 km to 50 km.

Lexical Relations： Measuring the Proficiency of the Saudi EFL Learners and Analysing the Obstacles

As teachers of EFL （English as a Foreign Language） in the Kingdom of Saudi Arabia, we are sometimes flabbergasted by the errors that the/earners make in their English scripts. Apparently, there was no pattern to these errors. However, when the researcher observed the frequency of similar error over a few years of her experience as an EFL faculty for Saudi learners, the theory of Lexical Relations appeared to offer an answer. Therein also lies the genesis of the current study. In a positive development, the study did bring to light certain factors that directly played a role in the Saudi EFL learners＇ English errors. These have been presented in this paper with the hope that with the diagnosis in hand, it will be easier for the EFL teachers to find a solution to the dearth of English proficiency among the Saudi EFL learners.

Development of Online Machining and Measurement System in Die and Mold Manufacturing： Concept and Fundamental Experiments

The corrective machining to compensate the resulting errors is usually tried at plural times based on the trial-and-error process when the machining is realized in die and mold manufacturing. This corrective machining has an influence on accuracy and efficiency and is an important factor. The measurement system for measuring the forms of die and mold at all times is essential in order to machine the die and mold with high accuracy and efficiency. However, the problems of management and operation errors are found in compensating process of die and mold machining. In this paper, an online machining and measurement system in die and mold manufacturing is developed in order to overcome these problems. In this online system, 2-axis control system is added to a surface roughness measuring instrument, and both NC machining program and measured data are linked and controlled using a same computer. Therefore, the machining and measurement can be recognized for consistent process, and can be realized on the machine. This system has the advantages such as the high accuracy, low-price, and online convenience and so on. The possibility of practical use of this online system was investigated by fundamental experiments.

A multi-functional dynamic state estimator for error validation:measurement and parameter errors and sudden load changes

We propose a new and efficient algorithm to detect, identify, and correct measurement errors and branch parameter errors of power systems. A dynamic state estimation algorithm is used based on the Kalman filter theory. The proposed algorithm also successfully detects and identifies sudden load changes in power systems. The method uses three normalized vectors to process errors at each sampling time: normalized measurement residual, normalized Lagrange multiplier, and normalized innovation vector. An IEEE 14-bus test system was used to verify and demonstrate the effectiveness of the proposed method. Numerical results are presented and discussed to show the accuracy of the method.