Design of testability for analogue fault diagnosis

With the rapidly increasing complexity of circuits and systems, the ability adequately to design a diagnosable circuit or system is a prime requisite for rapid fault location. In the present paper, a necessary and sufficient condition for pseudo-circuit generation is presented for the use of the pseudo-circuit in the self-test algorithm. to determine the diagnosability of a designed circuit, a testability condition is presented with examples. the unique feature of these conditions is that they depend only on the topological structure of a given circuit, not on the component values; therefore, these conditions can be implemented in both linear and non-linear circuits or systems. With the aid of a computer, the test points may be generated automatically by the proposed algorithm. Based on the proposed algorithm, the design of testability can be established.     

一种离散事件系统边界可诊断性验证方法

针对有效验证离散事件系统故障后是否具有可诊断性问题,设计了一种基于Petri网的边界可诊断性的验证方法。首先,根据Petri网的结构特性,提出了显示可达图的概念及其构建算法;其次,提出了一种基于显示可达图的验证器及其构造算法,分析系统故障发生后是否具有可诊断性以及计算满足系统可诊断性的边界值;最后,通过实例对所设计的方法进行验证。实验结果表明,设计方法可以有效验证系统故障后是否具有可诊断性并计算系统满足可诊断性的边界值,计算过程较为简单,对实际工业应用中离散事件系统故障可诊断性问题具有借鉴意义。     

断路器绝缘拉杆的可靠性验证

断路器在频繁操作的情况下,其绝缘拉杆有可能因为疲劳破坏而发生断裂。为了确保断路器在整个寿命期内绝缘拉杆不会因为疲劳而断裂或将其控制在某一范围内,可以在断路器绝缘拉杆设计完成后,通过测定绝缘拉杆的运行载荷,然后进行疲劳试验得到绝缘拉杆在预期寿命时的受力状况,最后再对试验数据进行统计分析,以得到绝缘拉杆在寿命期内的可靠度系数,并确认其是否满足设计要求,如果必要,也可以根据试验中的薄弱点进行针对性改良。     

四维坐标系下并网型光伏微电网故障区域判定技术

为了合理划分微电网拓扑结构,精准判定各种微电网故障情况下的故障区域,提出一种四维坐标系下并网型光伏微电网故障区域判定技术。令微电网拓扑结构为坐标图,设备节点为坐标点,以坐标点间最小欧式距离最大化,平均最近邻坐标点数量最小化为划分依据,通过球填充四维坐标点集的集合划分方法,划分微电网拓扑结构,获取微电网划分区域;以各划分区域为节点,断路器为边,通过图论算法构建微电网故障数学模型,依据故障前后功率变化量和区域故障电流方向,建立故障区域判定矩阵,实现故障区域判定。试验证明：该技术可有效划分微电网拓扑结构,划分后可有效提升微电网信号传输效果;在出现多重故障、两相故障与系统侧故障情况下,该技术均可精准判定故障区域。     

应对信息缺失的变电站广域后备保护研究

变电站测量点信息缺失会导致站内继电保护无法正确响应故障,进而对整个电力系统安全、稳定运行造成严重影响。基于变电站与相邻站的拓扑结构、测量以及状态等多源信息,提出了一种应对变电站信息缺失的新型广域后备保护方案。首先,根据信息缺失相邻测量点的故障分量方向元件的判别结果,初步确定短路故障是否位于保护区内;如果判别为区内,广域后备保护则依次断开信息缺失测量点位置的断路器,并根据方向元件的判别结果进一步确定故障位置。在PSCAD/EMTDC仿真环境下对该保护方案的性能进行验证,仿真结果表明该方案能够有效应对各种信息缺失的故障情况,并且该保护方案具有适应性强、不存在故障死区、不受断路器拒动影响等优势。     

考虑传输容量约束的配电网可靠性快速评估

在最短路法的基础上提出一种等值递推的可靠性等值计算方法,该方法按负荷点与馈线根节点之间的距离对其进行分层排序,并根据负荷所在节点的层号逐级计算其可靠性指标。在计算每一层负荷点的可靠性时,同时求出该层及以上所有设备的可靠性等值电路并为后续计算所用。另外提出一种计算形式简单的应用于辐射状电网的定雅可比矩阵牛顿潮流法,用于计算传输容量对配电系统可靠性的影响。基于图上因子分解法对辐射状电网的网络拓扑和因子图的拓扑进行了分析,证明2者是相同的,在此基础上开发了与面向支路的前代、回推法具有相似程序实现形式的牛顿潮流算法。该算法易于编程实现,同时保持了传统牛顿法的快速收敛性的优点。算例结果表明文章提出的可靠性评估算法具有较高效率。     

基于状态波形图的逻辑设计方法

本文提出了一种基于电器元件状态波形图进行继电接触式控制线路逻辑设计的方法，这种方法直观、简便、可靠，能用于任意复杂的线路，克服了传统逻辑设计法的繁琐、不直观以及待相区分组处理困难等缺点。     

串联型电压暂变补偿新拓扑及其控制方法研究

提出了一种简化的无变压器无储能电容的串联型电压暂变补偿主电路拓扑,并分析了其控制策略。新拓扑可使电路体积减小,成本更低;通过微调指令电压与负载电流的夹角可以达到控制母线电压幅值的目的;通过给指令电压施加一个微小的直流偏移电压,可以达到控制直流上、下母线电压的平衡的目的。介绍了改进的简化主电路拓扑,详细分析了其工作原理和控制方法。仿真结果验证了该方案的可行性和分析的正确性。     

Multi-objective optimization of the balancing of phases in primary distribution circuits

The primary distribution systems are among the more unbalanced three-phase networks. The unbalance of the phase currents causes two fundamental problems in the circuits: the increase of energy losses in the primary feeders and the presence of a high neutral current in normal operating status that makes it difficult the detection of ground faults by corresponding protections. These circuits are always protected at the substation. Nevertheless, other protections can also be located downstream in some sections or laterals of the circuit. Additionally, a circuit or some section of it can be supplied from another adjacent circuit in emergency conditions. In all the points where a ground fault protection is used, the maximum current of imbalance must be reduced to a minimum considering the several operating conditions that can change the circuit topology. This paper formulates the problem of phase balancing as a multi-objective optimization problem that minimizes: the neutral current at the desired points of the circuit, the energy losses in the primary feeders and the number of reconnected elements to achieve these objectives. The Non-dominated Sorting Genetic Algorithm (NSGA-II) has been used to develop the optimization application, which has shown a very successful performance in the solution of the phase balancing problem. A test example with all the needed data is solved to show the advantages of the presented approach.     

A method of analogue-digital multiple fault diagnosis

This paper develops an algorithm for multiple fault diagnosis of analogue-digital circuits. By sequentially partitioning the devices into those ‘assumed good’ and those ‘under test’, it is possible to develop a set of fault diagnosis equations which account for the special nature of digital components. A modified Newton-Raphson solution is then described which incorporates a digital state hypothesis testing scheme in the solution of the fault diagnosis equations for each partition. After solving for the input-output characteristics of the devices under test, a Boolean decision algorithm is used to analyse the test results of each partition and thus sequentially arrive at the set of faulty elements. A generic condition for diagnosability in terms of the circuit topology is given. Two examples are included to illustrate the technique.     

具有重合闸功能的限流型混合式高压直流断路器

直流断路器是直流输电系统安全稳定运行的核心装备。提出了一种具有重合闸功能的限流型混合式高压直流断路器(current limiting hybrid high voltage DC circuit breaker with reclosing function,RFL-HDCCB)。RFL-HDCCB拓扑利用限流支路的对称性,既实现了双向故障电流分断功能,又能够完成重合闸功能。无论是瞬时性故障还是永久性故障,都能够实现重合闸功能,恢复系统正常供电。分阶段对RFL-HDCCB的工作原理进行研究分析,然后对RFL-HDCCB进行了参数设计,最后利用PSCAD软件搭建起了系统仿真模型进行验证。验证结果表明,所提出的高压直流断路器与传统断路器相比,不仅能有效降低故障电流的上升率,减少对避雷器的耗能要求,而且降低了机楲开关的分断压力,限流能力明显,体现了所提方案的合理性。     

具有重合闸功能的限流型混合式高压直流断路器

直流断路器是直流输电系统安全稳定运行的核心装备。提出了一种具有重合闸功能的限流型混合式高压直流断路器(current limiting hybrid high voltage DC circuit breaker with reclosing function,RFL-HDCCB)。RFL-HDCCB拓扑利用限流支路的对称性,既实现了双向故障电流分断功能,又能够完成重合闸功能。无论是瞬时性故障还是永久性故障,都能够实现重合闸功能,恢复系统正常供电。分阶段对RFL-HDCCB的工作原理进行研究分析,然后对RFL-HDCCB进行了参数设计,最后利用PSCAD软件搭建起了系统仿真模型进行验证。验证结果表明,所提出的高压直流断路器与传统断路器相比,不仅能有效降低故障电流的上升率,减少对避雷器的耗能要求,而且降低了机楲开关的分断压力,限流能力明显,体现了所提方案的合理性。     

基于图数据库的电网CIM/E模型构建及网络拓扑

电力系统规模日益庞大、运行调整更加频繁,对分析计算实时性提出了更高要求。图数据库是近年来兴起的一种源于互联网海量数据并行处理的新型数据库,其数据模型可直观表达电网拓扑结构并易实现并行化遍历查询。首先,从数据模型和数据查询等方面介绍了图数据库的特点,分析了将其应用于大规模电力系统分析计算的潜在优势;其次,面向完整性、一致性以及高效性等准则,提出了基于图数据库并遵循CIM/E标准的电网数据模型设计方法,研发了数据模型装载工具。最后,在电网图数据库模型基础上,实现了一种并行化的电力网络拓扑分析算法。对实际大规模省级电网的计算结果表明,所提方法可显著提高拓扑搜索效率。     

新息图法识别多重网络结构动态变化

正确的拓扑结构是电网在线分析的关键问题之一,该文在提出预报预估网络和新息网络建模原则的基础上形成运行网络与预报预估网络及新息网络的叠加关系,使新息矢量元素间建立满足克希霍夫电路定律的联系。在新息图中定义连支推算新息矢量,提供了获取新息矢量元素的又一途径.由更新的新息矢量和预估预报矢量合成修正潮流矢量,在此基础上定义了修正预估比,以作为识别支路断开和闭合两种拓扑结构动态变化的依据。因而可以在有相关坏数据,无量测支路,甚至缺乏开关量信息的恶劣条件下,及时有效地识别网络结构的多重相关变化。为安全监控获取关键性实时信息提供了技术保障。     

斩波串级调速系统逆变侧电子保护电路的研究与设计

根据常规斩波串级调速系统的拓扑结构,分析了调速设备故障时接触器保护在动作保护过程中主回路的暂态过程。由于接触器动作时间较长,在其动作期间调速设备易受到高电压、大电流的冲击,导致电力电子器件损坏。针对接触器保护的弊端,设计了带电子保护电路的主回路拓扑结构。并分析了高压失电工况下常规的和带电子保护电路的斩波串级调速系统的暂态过程,同时进行详细的理论推导,得出高压失电工况下理论分析的依据。最后在模拟带载试验平台上分别对常规斩波串级调速系统和增加电子保护电路的调速系统在高压失电的工况下进行测试。测试结果表明理论计算与实际测量值基本一致,同时验证了电子保护电路有效解决了有源逆变结构下的高压失电或者逆变颠覆的问题。     

Direct analysis and synthesis of multiphase switched-current networks using signal-flow graphs

A by-inspection analysis and synthesis method for multiphase switched-current (SI) circuits using signal-flow graph (SFG) techniques is presented. The SFG is derived on the transistor level and the method is primarily useful for the hand analysis and design of small and medium-size SI circuits (e.g. SI filters, decimators, interpolators). Tables of commonly used SI circuits, in which the corresponding SFGs and circuits are given, make the derivation easy and fast. From the SFGs, not only the overall discrete-time transfer function, but also those in-between individual switching phases, are obtainable. With the proposed method it is straightforward to include non-ideal effects, such as finite output resistance of MOS transistors, clock-feedthrough and settling error. The method is also a useful tool for the synthesis of new SI circuits. It is shown that every low-sensitivity switched-capacitor (SC) circuit can be mapped directly into a low-sensitivity SI circuit with a corresponding topology. Examples of transformed SC circuits are given and two new double sampling integrators are introduced. © 1998 John Wiley & Sons, Ltd.     

Geometry of adaptive control: optimization and geodesics

Two incompatible topologies appear in the study of adaptive systems: the graph topology in control design, and the coefficient topology in system identification. Their incompatibility is manifest in the stabilization problem of adaptive control. We argue that this problem can be approached by changing the geometry of the sets of control systems under consideration: estimating n_p parameters in an n_p‐dimensional manifold whose points all correspond to stabilizable systems. One way to construct the manifold is using the properties of the algebraic Riccati equation. Parameter estimation can be approached as an optimal control problem akin to the deterministic Kalman filter, leading to algorithms that can be used in conjunction with standard observers and controllers to construct stable adaptive systems. Copyright © 2004 John Wiley & Sons, Ltd.     

分区互联装置桥臂闪络故障保护策略设计

随着城市电网的发展,电磁环网送电能力受限和短路电流超标问题越来越突出。分区互联装置是解决未来电磁环网有关问题的重要手段。提出了一种单变压器分区互联装置设计方案。系统故障时,单变压器分区柔性直流输电系统的故障特性和双变压器柔性直流输电系统的故障特性存在较大差别。当桥臂发生闪络故障时,换流器闭锁后交流系统通过子模块二极管形成故障通路,造成交流电流直流偏置,交流断路器将无法正常断开。为此,针对分区互联装置单变压器的拓扑结构,分析了桥臂闪络故障的故障特性,提出了基于闭合子模块旁路开关的保护动作策略,实现了故障情况下交流电流直流分量的快速衰减,确保了交流断路器可靠动作。通过单变压器分区互联装置PSCAD/EMTDC仿真测试,验证了故障分析及保护策略设计的正确性。     

关于OPGW设计选型中的最大短路电流计算

复合光缆地线（ＯＰＧＷ）设计选型中的一项主要工作是计算线路在发生单相短路故障时流经ＯＰＧＷ的最大电流。若采用简化工程计算方法,一定要注意该方法的适用范围和计算精度;采用相参数法建立电路模型,利用计算软件可以确切算出各支路上的短路电流,由此可以较合理地选择ＯＰＧＷ的型号。