Fault Detection Based on Hierarchical Cluster Analysis in Wide Area Backup Protection System

In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition.

Architecture Design for Integrated Wide Area Protection and Control Systems

This paper firstly reviews the recent development in power system protection and control, with special attention paid to the wide-area and integrated protection, in order to look into future development of integration of protection and control for smart grids. This paper mainly reports on the development of integrated wide area protection and control for power systems. The concept of integrated wide area protection and control is introduced, in which a hierarchical protection and control system provides the protection and control of wide area or regional power substations/ plants and their associated power network. The system is mainly divided into three levels, the local, the substation/plant and the wide area/regional protection and control. The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between the levels. One of the core elements in the system is the synchronised wide area communication network between the substations and the protection and control system, in which latest communication technology is employed. Another important player in the system is the wide area synchronized protection and control information platform, which not only enables the fusion three line of defence for power system protection and control, but also provides a perfect tool for the application of cloud computing to substations and power networks.

Communication Service Model for Wide Area Protection System Based on IEC 61850

In order to meet the requirements of information exchange varieties and manners in wide area protection system, a communication service model based on IEC 61850 is proposed. This service model can realize communication consistency and cooperation between different types of devices. Furthermore, the communication reliability and time delay performance are guaranteed to meet the requirements of relay protection from the upper layer. Message structure of generic sub-station event (GSE) and its communication mechanism are discussed. General methods to communicate digital information by generic substation status event (GSSE) and communicate analog sampling information by sampling analog value (SAV) of GSE are proposed.

Advancement in Wide Area Monitoring Protection and Control Using PMU’s Model in MATLAB/SIMULINK

A big step forward to improve power system monitoring and performance, continued load growth without a corresponding increase in transmission resources has resulted in reduced operational margins for many power systems worldwide and has led to operation of power systems closer to their stability limits and to power exchange in new patterns. These issues, as well as the on-going worldwide trend towards deregulation of the entire industry on the one hand and the increased need for accurate and better network monitoring on the other hand, force power utilities exposed to this pressure to demand new solutions for wide area monitoring, protection and control. Wide-area monitoring, protection, and control require communicating the specific-node information to a remote station but all information should be time synchronized so that to neutralize the time difference between information. It gives a complete simultaneous snap shot of the power system. The conventional system is not able to satisfy the time-synchronized requirement of power system. Phasor Measurement Unit (PMU) is enabler of time-synchronized measurement, it communicate the synchronized local information to remote station.

自然区划单独立法研究——以《长江保护法》为例

《长江保护法》是我国第一部自然区划单独立法,但相关研究只注重其对长江流域环境保护的影响,而忽视了它对自然区划单独立法的指导与借鉴意义。事实上,《长江保护法》对回答环境法治的三个问题提供了重要启迪。这三个问题是:为何自然区划需要单独立法?什么样的自然区划可以单独立法?自然区划法应如何立法?尤其是在强调立法节制的当下,为长江这一自然区划单独立法而不是修正涉及长江环境保护的环境法律,背后更是具有深远的立法考量与丰富的研究价值。以《长江保护法》为素材,对三个问题进行深入探讨,不仅有利于《长江保护法》未来的革新与发展,更能为新颁布的《黄河保护法》与《青藏高原保护法》等环境法律提供更为详备的理论支撑,进而最终作用于环境法治的发展与完善。《长江保护法》之所以被制定和颁布,缘于长江等自然区划的环保特殊性与现有法律的普适性存在不洽,并且自然区划的环境法治与环境法律的法域链接存在不洽,导致普适的环境法律无法满足自然区划特殊的环境保护需求,以及环境法治在自然区划上的实施过程与实施效果出现了断裂。自然区划需要单独立法,然而却并非所有的自然区划都需要单独立法,长江流域为自然区划立法提供了一个标准型样范。一方面,长江流域具备地理与人文的特殊性,长江流域的环境保护具备环保需求与规制手段的特殊性。另一方面,长江流域跨越多个行政区域,且又是一个完整而聚合的生态系统。因此,只有具有特殊性与广域性的自然区划才会产生与旧有环境法律的上述不洽,才具有单独立法的必要。为了让自然区划法适应于当前环境法律体系,且能更好地发挥其独特的优势与作用,需要将自然区划法置于环境法律体系中的特殊法地位,在法律适用中予以优先适用。并且,自然区划法具有一项不同于现有环境法律的原则——完整性原则。在该原则的指导下,自然区划法需要选择一种与当前环境法律有别的立法模式:确立以地方政府为规制对象,并围绕提升环境质量而非个体规制,赋予地方政府以法律责任。

智能电网中的继电保护技术分析

阐述智能电网环境下继电保护的特点,探讨继电保护技术的应用,包括信息技术、广域保护技术、区块链技术的应用,从而做出实时、高效的识别,有效控制相关继电保护装置拒动、误动状况。

高速铁路智能牵引变电所技术研究

研究目的:高速铁路牵引供电系统智能化是高速铁路智能化的重要组成部分,而智能牵引变电所是牵引供电系统智能化的核心,又是牵引供电系统智能化发展的趋势。目前我国高速铁路牵引变电所智能化技术处于初步发展阶段,智能化技术水平不高,本文对牵引变电所一次设备智能化、广域保护、辅助监控等技术方案进行研究,为实现牵引变电所智能化提出系统方案。研究结论:(1)从六个方面总结了智能牵引变电所的技术特征,便于对智能牵引变电所更深刻的认识;(2)智能牵引变电所采用“三层两网”布局,结构更加简化和清晰;(3)一次设备的智能化方案,建议新建设备采用集成化一体设备,改造设备采用外挂分离式设备;(4)采用网络化的广域保护实现了牵引网故障区段的隔离和供电臂的自愈重组,实现所间智能化控制;(5)本文研究内容可为牵引变电所的智能化提供技术参考。

智能电网中的继电保护技术应用

阐述智能电网继电保护技术的应用,包括智能传感技术、广域保护技术、网络通信技术、数字化技术、自身重构技术的应用。分析可再生能源的并网技术和智能电网继电保护技术的优化措施。

全并联AT供电方式下供电臂保护的适应性研究

广域保护测控系统的供电臂保护元件在越来越多的干线铁路投入运营。结合供电臂保护原理,深入分析了现场一起实际故障,研究了供电臂保护动作过程,分析了出口原因,为提高供电臂保护的健壮性、适应性提供了参考。

重载铁路牵引网网格化供电结构及控制方法研究

为了实现重载铁路能耗的精细化监测和管理,充分利用机车再生能量和牵引变压器利用率,提高供电可靠性,准确定位故障位置,缩小故障影响范围,达到提高供电效率和降低能耗的目的,结合变配电、信号处理、电力电子、微机保护和控制技术于一体,提出一种重载铁路牵引网网格供电结构及其控制方法。该方案能有效解决重载铁路能耗监测不健全和管理粗放等问题,具有显著的经济效益和工程实践意义。

基于上下行差流比原理的故障方向识别及广域保护方案

全并联AT供电方式下,智能牵引变电所的广域保护在牵引网故障时仅切除故障侧,非故障侧牵引网不断电。本文通过分析全并联AT供电方式下故障时变电所、AT所和分区所电流特征,提出了基于上下行差流比原理的广域保护故障方向识别判据,在发生PT断线时可缩小广域保护无法识别故障方向的范围,提高了广域保护的选择性。

Improving the performance of power system protection using wide area monitoring systems

Wide area monitoring(WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include monitoring the suitability of relay characteristics,supervisory control of backup protection, more adaptive and intelligent system protection and the creation of novel system integrity protection scheme. The speed of response required for primary protection means that the role WAM in enhancing protection is limited to backup and system protection. The opportunities offered by WAM for enhancing protection are attractive because of the emerging challenges faced by the modern power system protection. The increasingly variable operating conditions of power systems are making it ever more difficult to select relay characteristics that will be a suitable compromise for all loading conditions and contingencies. The maloperation of relays has contributed to the inception and evolution of 70 % of blackouts,thus the supervision of the backup protection may prove a valuable tool for preventing or limiting the scale of blackouts. The increasing interconnection and complexity of modern power systems has made them more vulnerable to wide area disturbances and this has contributed to several recent blackouts. The proper management of these wide area disturbances is beyond the scope of most of the existing protection and new, adaptive system integrity protection schemes are needed to protect power system security.

Fault area estimation using traveling wave for wide area protection

As the increasing number of Phasor Measurement Units(PMUs) are deployed, wide area protection in power systems has been gaining interest. In particular, fault detection, fault classification and fault area estimation are essential to reduce the damage of faults, and even prevent catastrophic cascades of failures. In this paper, we present a scheme for fault area estimation using PMUs and traveling wave theory. The purpose of this paper is to formulate a scheme for fault area estimation by calculating the approximate fault location based on traveling wave theory.This research has targeted at reliable operation of wide transmission system through the estimation of fault area.To verify the suggested scheme, the various simulations are performed in practical Korean power transmission system.The simulation results show that the proposed scheme has a good performance with high accuracy for estimating fault area.

Integrated Wide Area Protection and Control for Power Grid Security

The traditional“three defense lines”for power systems are based on local information and static protection&control strategy,which are not suitable to modern large-scale power systems.In order to improve the security of UHV hybrid power grids,the Integrated Wide Area Protection&Control(IWAPC)is proposed in this paper by applying the new technologies of synchronized high-speed communication,which integrates“three defense lines”and promotes existing wide area protection only for security control.The IWAPC is the hierarchical protection and control system which provides the protection and control for wide area power networks to improve their reliability and security.It is divided into three levels,the local bay level,the substation integrated protection level and the wide area protection level.The wide area real-time protection and control information platform is the most important part of the IWAPC,which is based on a synchronized wide area communication network.The key technologies and new development trends include network topology analysis,wide area backup protection,wide area intelligent reclosing,wide area load shedding,wide area auto-switching,overload cutoff and transfer,transmission section protection,intelligent system splitting and dynamic stability control.It cannot only integrate three lines of defense for power system protection and control,but also improve security of the power grid.

The research and the development of the wide area relaying protection based on fault element identification

The urgent problem of the relaying protection in the modern AC/DC hybrid connected grid and the development of the wide area communication,the information process and the intelligent technology powerfully promotes the development of the technology of the wide area relaying protection(WARP),which has become a research hotspot that attracts extensive attention.Originated from the basic concept of the wide area relaying protection,this paper analyses the advantages,the effects and the functions of the wide area relaying protection.The two main approaches to realize the wide area protection,which are on-line adaptive setting(OAS)principle and fault element identification(FEI),are introduced in this paper.Aimed at improving the performance of the backup protection,the research content and the technology demand of the wide area protection are proposed,meanwhile,the basic principle and the algorithm of the fault element identification are introduced.At last,the scheme of the limited wide area relaying protection based on the existing pilot channel of the main protection is discussed.

Guest editorial: special issue on wide area monitoring, protection and control in smart grid

Complexity of modern electrical power systems is steadily increasing.This is inspiring researchers and developers to propose new solutions capable to address a number of challenges,particularly those related to power system operation.A massive penetration of asynchronously connected renewable energy generation,the generation connected over inverters,is significantly changing the dynamics of modern power systems.From one hand,the power system response time is becoming shorter and at the same time the fault level is becoming smaller.This is significantly affecting requirements of control loops,as well as power system protection.

An adaptive limited wide area differential protection for power grid with microsources

The operation mode of power grids with intermittent distributed generations(DGs)changes frequently due to the bidirectional power flow.In comparison with the conventional grids,the protection relays in power grids with micro-sources are more difficult to set.To tackle this problem,this paper proposes an extended bus differential protection(EBDP)strategy based on the limited wide area(LWA).In this method,the micro-grids are divided into several protection areas at the core of the bus.The whole protection areas are protected by the wide area current differential relays,which are also configured to protect each component in this protection area.Moreover,the protection areas can be changed adaptively according to the power flow direction.Finally,a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform.The simulation results indicate that the proposed adaptive limited wide area differential protection(LWADP)has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault,and can be widely utilized in larger micro-grids.

基于VS-IRL的继电保护装置测试研究

在动态应力情况下,继电保护装置很容易发生三区误动作,导致电力系统级联跳闸,甚至使得用户端停电。对此,提出了增强型广域距离继电保护算法,利用实时脆弱性研究(VS)和故障检测方法(IRL)对常规三区备用继电保护装置进行测试,以在各种应力条件下识别故障。在继电保护装置发生意外跳闸之前,计算适当的装置脆弱性指数,并利用该指数对任意运行条件下的关键装置进行排序,来估计继电保护装置脆弱性的强度,一旦识别出一组高度易受攻击的继电保护装置(RPE),智能继电保护装置将监控测试这些RPE。最后通过在DDRTS平台上实现数字动态实时仿真验证该方案的有效性。结果表明该算法在不影响系统可靠性的前提下可以对继电保护装置进行测试,有效地增强了电力设备的全站保护运行,显著提高了远距离中继的安全性。

智能电网中的继电保护技术应用

阐述继电保护技术中的单原件保护、广域保护、智能传感器特点,分析继电保护配置方案,包括线路保护、组件保护、综合监测系统的应用。

智能牵引供电系统网络化广域保护通信通道

以数字化、智能化为特征的智能高铁,系统内各要素之间信息充分流通,实现信息空间和物理空间内数据实时共享、交互。数据信息的流通离不开通信技术的支撑和通信通道的建设。智能牵引供电系统是智能高铁的重要组成部分,文章以供电系统中的广域保护测控系统对通信通道的需求为出发点,分析其技术要求和组网方案,并结合现场实例说明了通信通道的重要性。