An algorithm for multiple fault diagnosis in analogue circuits

The paper deals with multiple fault diagnosis of analogue AC or DC circuits with limited accessible terminals for excitation and measurement and brings an algorithm for identificating faulty elements and evaluating their parameters. The main achievement is a method enabling us to efficiently identify faulty elements. For this purpose some testing equations are derived playing a key role in identification of possibly faulty elements which are next verified using a test of acceptance. The proposed approach is described in detail for double fault diagnosis. Also extension to triple fault diagnosis is given. Although the method pertains to linear circuits, some aspects of multiple fault diagnosis of non‐linear circuits can be also performed using the small signal approach. Two numerical examples illustrate the proposed method and show its efficiency. Copyright © 2006 John Wiley & Sons, Ltd.     

A generalized fault diagnosis method in dynamic analogue circuits

Fault diagnosis of analogue circuits is essential for analogue and mixed‐signal systems testing and maintenance. A new method is proposed in this paper for multiple fault diagnosis of linear analogue circuits in frequency domain. The Woodbury formula is applied to the modified nodal equation to construct the fault diagnosis equation, which relates the limited measured circuit responses with the multiple faults inside the circuit in a linear way. A recently developed ambiguity group locating technique is modified here to identify the faulty parameters directly. Computation cost is reduced compared to combinatorial search in traditional fault verification methods. Only one node is needed for voltage measurement, but multiple excitations on accessible nodes are required for fault identification. Parameter evaluation can provide the exact solution to the deviated values of faulty parameters. The faulty parameter deviations can have any finite values. Example circuits are provided to illustrate the proposed method. Two other methods for multiple analogue fault diagnosis sharing the same mechanism as the method proposed in this paper are also briefly described. The proposed method is extremely effective for the circuit with very limited accessible nodes and is also computationally efficient. Copyright © 2002 John Wiley & Sons, Ltd.     

Concurrent analogue fault simulation,the equation formulation aspect

Fault simulation is an essential tool for developing test patterns for circuits. Because the potential number of faults in a circuit is potentially very large, computational efficiency is an important consideration. In the digital domain, concurrent fault simulation is well‐established as an efficient tool. For analogue circuits, fault simulation is often performed by repeated insertion of possible faults and resimulation of the circuit. Consequently, methods for efficient concurrent analogue fault simulation are attracting attention. A review of existing methods of concurrent analogue fault simulation shows that most are based on a similar fundamental perturbation of the original fault‐free circuit equations, although the methods differ in the procedure applied after the circuit equations are formulated. We develop here a comprehensive set of element stamps, describing faulty elements, enabling effective and routine equation formulation for faulty circuits. These may be used no matter what method of fault simulation is later applied. These stamps are used in a new technique for concurrent analogue fault simulation, based on modified nodal analysis. A significant improvement in efficiency, compared with other methods, is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.     

大规模电路故障诊断的集团法

本文提出了一种可以诊断大规模模拟电路的新方法——集团法，它能不经过撕裂直接用于大规模电路，且能迅速缩小可疑故障集范围。本文详述了其诊断原理及诊断步骤，并给出了诊断实例。     

Estimation of circuit output measurements including statistically dependent parameters

An extension to the method for estimating statistical variables of output measurements, in order to take into account the statistical variations and matching dependencies between circuit parameters, is studied. The enhanced method results in sufficient estimations, while additional circuit simulations are needed. Comparative results from the application of the method and of the Monte‐Carlo analysis on three analogue circuits are presented to show the effectiveness of the extended method. Copyright © 2003 John Wiley & sons, Ltd.     

针对逻辑门功能异常的VLSI故障仿真方法研究

为准确评价测试集对超大规模集成电路（VLSI）内部故障的覆盖效果,提出一种VLSI故障建模与仿真方法。首先,在电路级综合运用仿真和实验手段向逻辑门内部注入多个故障,统计并分析这些故障对其功能的影响以构建由变异真值表（MTT）组成的故障字典;其次,考虑MTT及其发生的相对概率权重,提出一种有效的测试覆盖率评价模型,并将其应用于门级故障仿真算法中;最后,针对若干组合逻辑基准电路进行了实例验证,仿真实验结果表明,所提方法相较于经典的固定值故障模型能够更真实地反映测试集的故障覆盖能力。     

A new approach for automatic fault diagnosis in analogue circuits

In this paper the problem of fault diagnosis in analogue circuits is addressed by a method which can be regarded as an artificial intelligence approach. the topology of the circuit under test along with the nominal element values, the necessary element models and their possible failure modes are the basic tools used in the procedure. Fault location is accomplished using appropriate DC node voltage measurements under certain DC excitations on the nominal circuit and the faulty one. the detection of signal faults which have DC effects is the goal of the method; cases of faults with non-DC effects are also examined. Demonstrative examples are given to show the applicability of the method on passive and active analogue circuits.     

Current differential amplifiers: new circuits and applications

New CMOS current differential amplifiers are proposed suitable for analogue signal processing at high frequencies. They consist of simple current mirrors, which are easy to design and to implement in IC form. Low‐voltage low‐power design is feasible. Relying on these devices a number of applications are obtained, including lossy and lossless integrators, simulated inductors, active filters, and harmonic oscillators. Theoretical expressions are given for all of the proposed new circuits. The verification of the circuits is also achieved by simulation. Copyright 2001 © John Wiley & Sons, Ltd.     

模拟电路故障诊断的小波方法

利用小波与神经网络相结合的方法,将小波作为消噪工具,对信号进行消噪和小波多尺度分解,进行正交和归一化处理后,提取特征信息,作为样本输入神经网络进行分类,提出了模拟电路故障诊断的系统方法.本文详述了其诊断原理及诊断步骤,并给出了诊断实例.     

A method for fast simulation of multiple catastrophic faults in analogue circuits

The paper offers an efficient method for simulation of multiple catastrophic faults in linear AC circuits. The faulty elements are either open circuits or short circuits. The method exploits the well‐known Householder formula in matrix theory to find the node voltages deviations due to the perturbations of some circuit elements. The main achievement of the paper is a systematic method for performing the simulation of all combinations of the multiple catastrophic faults. The method includes two new procedures enabling us to find very efficiently the node impedance matrix of the nominal circuit and inverses of some matrices corresponding to different fault combinations. The procedures are the crucial point of this approach and make it very efficient. Consequently, the amount of the computing power needed to carry out all the simulations is significantly reduced. Numerical examples illustrating the proposed approach are provided. Copyright © 2008 John Wiley & Sons, Ltd.     

A new protection scheme for fault detection, direction discrimination, classification, and location in transmission lines

This paper presents a new adaptive fault protection scheme for transmission lines using synchronized phasor measurements. The work includes fault detection, direction discrimination, classification, and location. Both fault-detection and fault-location indices are derived by using two-terminal synchronized measurements incorporated with distributed line model and modal transformation theory. The fault-detection index is composed of two complex phasors and the angle difference between the two phasors determines whether the fault is internal or external to the protected zone. The fault types can be classified by the modal fault-detection index. The proposed scheme also combines online parameter estimation to ensure protection scheme performance and achieve adaptive protection. Extensive simulation studies show that the proposed scheme provides a fast relay response and high accuracy in fault location under various system and fault conditions. The proposed method responds very well with regards to dependability, security, and sensitivity (high-resistance fault coverage).     

深度学习辅助的区域交直流配电网区间状态估计

针对区域交直流混合配电网中实时量测覆盖率低、量测误差分布具有不确定性的问题,提出了基于深度神经网络(DNN)伪量测建模的交直流配电网区间状态估计方法。该方法首先对DNN进行离线训练,然后将实时量测数据和电压源换流器控制的变量值作为DNN的输入特征,建立伪量测模型;接着,在实时量测更新时,利用已训练好的DNN快速生成伪量测;最后,对伪量测和实时量测的不确定性采用区间形式建模并进行区间状态估计,进而准确监测交直流系统状态。算例仿真结果表明,所提方法能够避免对量测误差的概率分布进行假设,并且能够在低冗余量测配置或量测缺失时,准确获得交直流配电网状态变量的上下界信息。     

Differential equation description and Chebyshev approximation of linear time‐invariant circuits

The approximation technology of analogue circuit functions is crucial to the computer‐aided simulation, analysis, and design automation of electronic circuits. Chebyshev polynomials and various differential equations are proposed in this paper to approximate the functions of linear time‐invariant circuits. The coefficient calculation methods of the Chebyshev expansion and the differential equation matrices are thoroughly deduced, and the construction methods employed in the functions and the actual time mapping of the linear time‐invariant circuits are presented in this paper. An example of an analogue filter verifies the effectiveness and accuracy of the proposed approximation algorithm and elaborates on the selection process of the order number and the time step length of the Chebyshev expansion according to the demanded truncation error.     

A uniform approach to mixed-signal circuit test

Owing to the analogue nature of many industrial processes and the increasing use of microprocessor techniques, many circuits nowadays carry mixed (digital and analogue) signals. As complexities of these circuits increase, the testability of mixed-signal circuits has become an important issue that must be dealt with by both design and test engineers. A systematic approach to study the testability of mixed-signal circuits is urgently needed, because current ad hoc methods cannot efficiently handle increasingly complex and ever-changing circuits. In this paper we develop a uniform and systematic approach to the mixed-signal circuit testability problem. The approach is based on a recently developed theory of discrete event systems. It is suitable for the following tasks: (i) checking the testability of a circuit; (ii) computing the minimum test set; (iii) finding the fault coverage; (iv) dividing a circuit into testable modules. © 1997 by John Wiley & Sons, Ltd.     

大型发电机的多特征参量故障发生概率评定方法(英文)

It is conducive to ensure the safety and reliability of the power system by means of timely and accurate evaluation of the reliability of large generators.An evaluation method of fault probability for large generators based on multi-characteristic parameters is proposed in this paper,which can be employed to solve the difficult problem of evaluating the occurrence probability of fault modes of large generators in the process of reliability evaluation.Firstly,the set of fault characteristic parameters for a large generator is established on the basis of a large number of operation experiences and preventive test code for the large generator.Secondly,according to the features of the fault characteristic parameters,two estimation methods of the fault mode occurrence probability are proposed,which are based on the fuzzy membership function and the relative deterioration degree,respectively.Finally,on the basis of the improved analytic hierarchy process(IAHP) method,the composite estimation method of the fault probability for a large generator is presented,which can reasonably and adequately use the information of various characteristic parameters.An assessment case is provided to illustrate the specific process of this evaluation method and verify its effectiveness.     

基于神经网络的数字电路多故障测试生成算法

针对数字电路中多故障测试生成效率较低的问题,提出了基于神经网络的数字电路多故障测试生成算法。依据故障转换方法把数字电路多故障测试生成问题转换成为单故障测试生成问题,采用神经网络的方法对单故障电路构造故障的约束网络,通过使用遗传算法求解故障约束网络能量函数的最小值点获得故障的测试矢量。在ISCAS’85国际标准电路上的实验结果表明,故障平均测试生成时间在0．017s以下,故障覆盖率在96％以上。与其他算法相比,测试生成效率明显提高。     

Design for testability of high‐order OTA‐C filters

A study of oscillation‐based test for high‐order Operational Transconductance Amplifier‐C (OTA‐C) filters is presented. The method is based on partition of a high‐order filter into second‐order filter functions. The opening Q‐loop and adding positive feedback techniques are developed to convert the second‐order filter section into a quadrature oscillator. These techniques are based on an open‐loop configuration and an additional positive feedback configuration. Implementation of the two testability design methods for nth‐order cascade, IFLF and leapfrog (LF) filters is presented, and the area overhead of the modified circuits is also discussed. The performances of the presented techniques are investigated. Fourth‐order cascade, inverse follow‐the‐leader feedback (IFLF) and LF OTA‐C filters were designed and simulated for analysis of fault coverage using the adding positive feedback method based on an analogue multiplexer. Simulation results show that the oscillation‐based test method using positive feedback provides high fault coverage of around 97%, 96% and 95% for the cascade, IFLF and LF OTA‐C filters, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

A novel method for SLG fault location in power distribution system using time lag of travelling wave components

This paper presents an approach to single line‐to‐ground fault location in a power distribution system based on the time lag of different modal components . It is a single‐ended method applicable to unsynchronized measurements. The fault location formulation is derived by analyzing the traveling wave propagation characteristic in a distributed parameter model. To tackle the key problem of ground‐mode velocity estimation, an iterative velocity method based on prior knowledge is first proposed. Since the practical measurements are not ideal because of sensor accuracy and nonequivalent transient response, fuzzy neural network is utilized to process traveling wave data acquired at multiple measurements to get an error‐tolerant effect. Furthermore, electromagnetic transient simulations for a 34‐bus test feeder system under various conditions of fault resistances, inception angles, and distributed generator access reveal the robust estimation of fault location. The performance of the proposed method is also validated by simulations with noisy and noise‐free measurements. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于SVM的电力变压器内部故障部位的概率估计

目前变压器智能故障诊断大多是以油中溶解气体为特征对故障性质的诊断,缺乏对内部故障部位的分析及量化的诊断结果。针对上述问题,提出一种基于SVM的电力变压器内部故障部位的概率估计模型。该模型结合SVM与概率建模的优点,充分利用油中溶解气体和电气试验数据的互补信息,运用SVM后验概率理论,对变压器内部可能发生故障的部位进行概率估计,克服了标准SVM硬判决输出的缺陷,以概率的形式给出诊断结论。通过实例分析表明,该模型不仅故障识别率较高,还具有良好的概率分布形态,具有较好的实用性和推广性。     

Fault location observability analysis and optimal meter placement based on voltage measurements

Various transmission line fault location algorithms have been proposed in the past depending on measurements available. These methods evince that if a sufficient number of meters are placed in a power network to record the fault measurements, then the fault location can be reliably estimated. A relevant question to ask may be: how many meters are sufficient in order to derive a reliable and unique fault location estimate for a given network? This paper addresses this question by defining and performing the fault location observability analysis. An optimal meter placement scheme is proposed for determining the optimal locations to place meters so as to make the system observable while minimizing the required number of meters to reduce costs. The proposed method is especially useful for power networks where digital relays have not yet been widely adopted and measuring devices such as digital fault recorders are deployed for monitoring purposes. A sample power network has been employed to illustrate the proposed method.