Fault Detection and Protection System of Electric Railway Substation

The industrial power systems are moving to digital networks,and unmanned systems are increasing recently with the technological development of information and communication technology.In particular,reliability of system operation is very important for stable power supply.Most industrial power distribution facilities use a 154 kV or 22.9 kV extra HV(high voltage)power system,and a special monitoring system is required because a large loss occurs when an error occurs in the power facility in the field.Although digital protection relay(IED;intelligent electronic device)and FR(fault recorder)are applied to the field to protect the power system,various improvement activities are still ongoing.In this paper,a 22.9 kV high-voltage panel and its test bed,which are widely used in railway stations,tunnels,substations and large plants,were tested as test subjects.The developed fault detection system automatically starts the AL(auto-lock)circuit or outputs an alarm signal to user by monitoring in real time problems such as CT(current transformer)-open and poor-contact that the existing digital protection relay cannot cover.In addition,it is intended to increase the safety and reliability of the power system by blocking various accidents in the system in advance and accurately analyzing the causes of faults with the developed fault detection system.

Serial Failure Diagnosis of a Transmission Line Protection Relaying System by Petri Nets

With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.

Fault Classification and Localization in Power Systems Using Fault Signatures and Principal Components Analysis

A vital attribute of electrical power network is the continuity of service with a high level of reliability. This motivated many researchers to investigate power systems in an effort to improve reliability by focusing on fault detection, classification and localization. In this paper, a new protective relaying framework to detect, classify and localize faults in an electrical power transmission system is presented. This work will extract phase current values during ( )th of a cycle to generate unique signatures. By utilizing principal component analysis (PCA) methods, this system will identify and classify any fault instantaneously. Also, by using the curve fitting polynomial technique with our index pattern obtained from the unique fault signature, the location of the fault can be determined with a significant accuracy.

A Complete Analytic Model for Fault Diagnosis of Power Systems

现代大规模互联电网提高了电力系统运行的稳定性和经济性,同时也给电网的故障诊断增加了难度。对电网保护配置和断路器动作规则进行深入分析,提出一种新的电网故障诊断模型——完全解析模型,并为基于此模型的故障诊断提出一种实用有效的求解方法。在完全解析模型中,故障假说（即可疑故障设备的故障情况）与保护、断路器的动作情况及拒动和误动情况一同表示成逻辑变量,而保护配置和断路器动作规则以逻辑方程组形式进行充分表达,逻辑方程组的每个解析解对应一个故障模式（设备故障状态和保护动作、断路器跳闸状态及拒动/误动情况）,是对故障情形的完整解释。本模型对故障诊断规则和保护、断路器的动作逻辑进行完全解析,并完整保留了故障设备、保护动作和断路器跳闸之间的耦合关系,克服了已有解析模型的缺陷。算例表明,保留完整耦合关系的完全解析模型可有效提高故障诊断的准确性和容错能力。

Online Diagnosis and Monitoring for Power Distribution System

Recently, power distribution system is getting larger and more complex. It is very difficult even for the experts to diagnosis and monitoring to made best action. This motivated many researchers to investigate power systems in an effort to improve reliability by focusing on fault detection and classification. There have been many studies on problems but the results are not good enough for applying to real power system. In this paper, a new protective relaying framework to diagnosis and monitoring faults in an electrical power distribution system with. This work will extract fault signatures by using ellipse fit using least squares criterion during fault condition. By utilizing principal component analysis methods, this system will identify, classify and localize any fault instantaneously.

Fault Waveform Regenerator and Its Digital Closed-Loop Modification Technique

In order to provide a novel and more effective alternative to the commonly used relay protection testing device that outputs only the sinusoidal testing signals, the concept of fault waveform regenerator is proposed in this paper, together with its hardware structure and software flow chart. Fault waveform regenerator mainly depends on its power amplifiers (PAs) to regenerate the fault waveforms recorded by digital fault recorder (DFR). To counteract the PA’s inherent nonlinear distortions, a digital closed-loop modification technique that is different from the predistortion technique is conceived. And the experimental results verify the effectiveness of the fault waveform regenerator based on the digital closed-loop modification technique.

Accident of Large-scale Wind Turbines Disconnecting from Power Grid and Its Protection

There were many accidents of large-scale wind turbines disconnecting from power grid in 2011.As singlephase-to-ground fault cannot be correctly detected,single-phase-to-ground fault evolved to phase-to-phase fault.Phase-to-phase fault was isolated slowly,thus leading to low voltage.And wind turbines without enough low voltage ride-through capacity had to be disconnected from the grid.After some wind turbines being disconnected from the grid,overvoltage caused by reactive power surplus made more wind turbines disconnect from the grid.Based on the accident analysis,this paper presents solutions to above problems,including travelling waves based single-phase-to-ground protection,adaptive low voltage protection,integrated protection and control,and high impedance fault detection.The solutions lay foundations in theory and technology to prevent large-scale wind turbines disconnecting from the operating power grid.

基于等效序阻抗差异特征的低频输电线路差动保护优化方案

低频输电线路故障时,两侧短路电流均由模块化多电平矩阵变换器提供,两侧短路电流相角均受控且幅值相当,导致差动保护灵敏度严重下降。分析了低频输电系统定电压控制侧和功率控制侧的等效正、负序阻抗特征,指出因控制策略不同,系统故障时两侧等效正、负序阻抗特征存在明显差异。分析了低频输电线路区内和区外故障两侧保护装置测量到的等效序阻抗之间的差异性和相似性,基于此特征构建了两侧等效序阻抗差异指标,提出了基于等效序阻抗差异指标的差动保护制动系数优化方法。仿真结果表明,所提方案能够显著提升低频输电线路区内故障时差动保护的动作速度和动作灵敏性。

多间隔信息融合的母线保护电流互感器断线再开放策略

对于电流互感器(CT)断线后发生金属性故障的情景,现有母线保护采取的闭锁差动保护动作方式将会引发多个变电站停电。此外,当母线区内发生高阻接地故障时,现有母线保护判据可能会将其误判为CT断线故障,不利于电力系统的安全稳定运行。针对这一问题,提出了一种母线保护CT断线再开放策略,该策略基于断线间隔与非断线间隔的零序电流变化量对负荷波动和故障进行区分,并基于非断线间隔的差流有效值和间隔失灵保护信息对区内外故障进行判别。实时数字仿真系统仿真结果验证了所提CT断线识别判据和再开放策略的正确性。

复杂大电网非预设性运行工况下的继电保护动作适应性仿真分析

非预设性运行工况下的突发事件多,导致继电保护逻辑的适应性较差,不合理区域较多,为此,进行复杂大电网非预设性运行工况下继电保护动作适应性仿真分析。分析历史常规故障,标记故障点最常发生位置,构建零序、负序方向元件模型、距离元件模型、纵联电流差动元件模型,观察复杂大电网非预设性运行工况下的电网参数变化情况,第一时间掌握电网的耦合性,不断选择电网所需的继电保护动作逻辑,确认继电保护动作适应性。仿真实验表明,将故障点设置在保护区域内和区域外,继电保护动作能够根据故障选择不同保护模型进行故障母线切除或者保护不动作,适应性好。

个人信息侵权“违法性”的二阶构造及其规范进路

“违法性”具有平衡个人信息权益保护与商业利用的功能。个人信息侵权不以违反管理性规范为前提。违反管理性规范不一定会导致个人信息侵权。违反以保护他人为目的之法律规范的行为构成个人信息侵权行为。个人信息侵权中,在“保护他人”的侵权法实质内涵的基础之上,区分《个人信息保护法》中的管理性规范与保护性规范。个人信息侵权中,面临“遮蔽过错要素”的干扰,故在以过错为核心的保护性规范的基础上,明确个人信息侵权中侵权行为“违法性”的二阶构造,对个人信息侵权“违法性”采区分论。在存在“遮蔽过错要素行为”时,采“损害推定违法”,违法可以被推翻,从而实现个人信息侵权保护的周延性。

分接开关可控移相变压器保护配置及故障特征分析

移相变压器是一种经济型的潮流调节设备,可提高电网运行的安全性和经济性。为了实现分接开关可控移相变压器工程化应用,首先,针对电流电压互感器配置情况,提出了移相变压器的主保护配置方案,并分析了各保护元件的保护范围。其次,提出了基于控保协同的差动计算自适应调整策略,可根据分接开关的实时档位实现移相变压器差动保护计算的自适应调整。接着,给出了基于移相变压器差动平衡的各侧电流校验方法,可用于校验电流互感器的接入极性和参数。最后,通过仿真和实际波形,分析了不同故障下和空充时的波形特征以及保护的适应性,并证明了所提方法和保护配置的有效性。

New Principle for Grounding Fault Feeder Detection in MV Distributions with Neutral Ineffectively Earthed

A new principle for grounding fault feeder detection based on negative sequence current variation and energy dissipated in the fault point is presented. It has high precision in both isolated systems and resonance earthed systems, even in full compensated systems. And it can be installed at the local control unit of feeder in distribution automation systems, such as field terminal unit (FTU). This principle is verified by EMTP simulator and experimentation.

适用于严苛正序助增系数计算的故障位置快速选取方法

针对相间距离保护整定计算中严苛正序助增系数对应故障位置的选取效率较低及精度不足的问题,提出适用于严苛正序助增系数计算的故障位置快速选取方法。首先,基于节点阻抗矩阵及矩阵元素的修改公式,推导了正序助增系数表达式,整理得到13类正序助增系数随故障位置移动的可能变化趋势。然后,通过研究正序助增系数随故障位置移动的变化规律,得到5条严苛正序助增系数对应故障位置的选取判据,提出一种适用于各类复杂网络结构的故障位置快速选取方法。最后,通过IEEE多节点标准测试系统验证了所提方法的有效性。故障位置选取精度高于规程选取方法,选取效率高于多点选取方法。

数字化变电站继电保护装置故障智能检测识别方法研究

为了提升变电站的数字化水平、提高故障的识别精度,文中对继电保护装置故障的智能检测算法进行了研究,并设计了一种基于灰色关联分析的堆栈编码器网络(GRA-SAE)。该网络以自动编码器为基本单元,可实现数据的自动化特征提取。通过支持向量机(SVM)对提取的特征进行分类识别,并引入灰色关联分析法优化了传统SAE算法中隐藏节点的结构,从而提升了算法的拟合能力。在自建数据集上进行的仿真结果表明,相较于SAE-SVM算法,该算法对异常数据与线路故障的识别精度分别提升了4%和10.27%,证明了GRA-SAE-SVM算法在复杂分类场景下具有更显著的优势。

应对变电站二次直流失电的超高压输电线路相间保护方案

变电站二次直流失电会导致本站继电保护装置等设备失去供电电源而无法动作,本站出线发生故障时需要依靠上级变电站的远后备保护进行切除。针对变电站二次直流失电情况下超高压输电线路发生相间短路故障时保护远后备灵敏度不足的问题,提出了一种应对变电站二次直流失电的超高压输电线路相间保护方案。首先,根据超高压电网相间故障时负序电流的自然分布特性,探讨了反时限负序过流保护的远后备应用可行性和相间距离保护的补充特性,确定了相间故障远后备保护的构成思路。接着,研究了助增系数和负序电流对反时限负序过流保护整定时间定值的影响,讨论了临界助增系数的确定方法和反时限负序过流保护的时间定值整定方法。然后,提出了反时限负序过流保护为主、相间距离保护为辅的应对变电站二次直流失电的超高压输电线路相间保护方案。最后,以IEEE 39节点系统和某实际500 kV电网作为仿真算例,对所提方案的有效性进行验证。

考虑三次谐波调制的柔直系统交流侧单相接地保护研究

为了简单可靠地实现柔直系统阀交流侧单相接地保护,针对阀交流侧中性点经阻抗接地的柔直系统,分析了交流侧的零序基波分量与直流侧的共模分量,推导了金属性接地故障下故障端与非故障端的零序基波电压、电流解析式。针对采用三次谐波注入调制策略的柔直系统,分析了三次谐波调制引起的纵向三次谐波电压相位特征,推导了三次谐波电压、电流的表达式,提出了利用中性点零序基波电压和三次谐波电压来判断接地故障及其位置的保护判据,并给出了相应的整定计算方法。不同工况下的仿真结果表明,当保护安装端发生接地故障时保护可以正确动作,当其他端发生接地故障时保护不会误动作。

计及拓扑结构变化的分布式自适应电流保护方法

针对配电网络重构、线路拓扑关系发生变化导致保护误动或拒动的问题,提出一种自适应电流保护方法,该方法由智能终端实时获取配电线路的拓扑关系,自适应调整保护定值,实现自适应保护和故障自愈功能。该方法可减少配置维护工作量,提高配电网的可靠性。为了实现互操作性,建立了基于IEC 61850标准的分布式自适应电流保护相关的逻辑节点,构建了分布式自适应电流保护应用的信息模型,以期能为现场应用提供一定的参考。

基于高阻接地距离继电器的零序电流保护选择性提升方案

交流线路零序电流保护最末一段均采用300 A定值,存在无序跳闸风险。因此,文中提出了基于零序电抗线和非故障相极化的高阻接地距离继电器原理。继电器采用先选相、后测量的技术路线,选相元件将零序电抗线与非故障相极化方法相结合,构成多种组合判据,以分工完成选相。由于保护安装处零序电流与故障点零序电流存在相位差异,单相接地故障的故障相和相间接地故障的超前相的零序电抗线在故障点位于整定点附近时存在混叠区。区内近端、低阻单相接地故障时非故障相工作电压大幅变化,不利于区分混叠区的两类故障,故将选相元件分为低阻模块和高阻模块。低阻模块采用下偏的零序电抗线,用于识别近端、低阻故障;经低阻模块辅助后,高阻模块只需针对性处置故障点位于整定点附近的故障,可有效区分两类故障。选相完成后,通过非故障相极化的方法获得故障前工作电压,从而确定继电器的动作特性。高阻距离继电器的耐过渡电阻能力远超规程要求,提高了接地后备保护对高阻接地故障的选择性。

超、特高压交流线路反时限零序过流后备保护的整定建议

针对国家电网“六统一”线路保护装置,提出了超、特高压交流线路反时限零序过流保护的整定原则。反时限零序过流保护在保证灵敏性方面并无困难,整定原则的核心问题是解决选择性和速动性的矛盾。根据该保护的原理和逻辑提出了转折电流的概念以及接地距离保护与反时限零序过流保护的配合原则;充分考虑配合时间定值和最小时间定值对保护动作特性的影响,综合超、特高压电网实际短路电流水平和接地距离保护的过渡电阻耐受能力,将反时限零序过流保护低电流区的选择性与接地距离保护高电流区的选择性进行结合,提升了对接地故障全域电流范围的选择性切除能力;提出了方向元件投退原则。通过对某省级电网进行算例分析,验证了整定原则的有效性,该整定原则已经在实际电网中进行了应用。