Multifunction digital relay commissioning and maintenance testing

This paper discusses with the protective relay technology over the past 25 years has evolved from single-function electromechanical (EM) relays, to static (electronic) relays, and, finally, to digital multifunction relays. A significant number of these multifunction digital relays are being installed on medium-voltage electric power systems within industrial and commercial facilities. As was required in earlier EM and static relay technologies, digital relays also require commissioning and relay-setting verification. This article discusses the unique challenges the user faces in testing and commissioning digital multifunction relays. It also explores the impact on maintenance testing of self-diagnostics, the digital relay's internal capability to check itself for failures.     

Application considerations of static overcurrent relays: a workinggroup report

The technology of static overcurrent relays has developed very rapidly in the past few years. These developments have produced changes in the way they are applied from electromechanical (EM) relays and, further, offer many new features to provide greater utilization than previously possible. A Working Group of the Medium-Voltage Subcommittee of the Power Systems Protection Committee began examining the impact of these developments several years ago. This report documents the results and describes the nature of the changes and the new areas of application. It is presented acknowledging the fact that this is really an interim report, since static relay technology is a very dynamic technology with many more innovations yet to be developed     

Field-Programmable Analog Array Based Distance Relay

Protective relays have been designed with different technologies resulting in electromechanical, solid-state, and numerical devices. Speed and reliability are the two most important characteristics of a protective relay. Other capabilities such as monitoring and recording are supposed to be of secondary priority. Without any doubt, present-day numerical relays provide considerable capabilities and advantages but they have not improved speed of operation in comparison to their solid-state counterparts. With advancements in analog technology which has become more mature recently, the idea of using mixed signals in several applications has started. The new technology using combination of field-programmable analog arrays (FPAAs) and digital technologies seems to be a breakthrough and has the potential to provide better performance than the present-day numerical relays. In this paper, use of FPAAs for designing and implementing protective relays is investigated for the first time in literature. A distance relay design and its hardware implementation using FPAAs is described. Test results are reported.      

New overcurrent RST80 relays and their time-current characteristics

The problems are considered of the operation of electromechanical overcurrent relays and construction of relay protection using their time-current characteristics. The distinctive features of new static overcurrent RST80 relays are presented. It is shown that the four types of time-current characteristics implemented in the RST80 relay provide flexible coordination with the characteristics of the protection of the adjacent equipment.     

SEL—321相间距离保护静态特性与动态特性及试验方法

介绍在调试过程中对采用负序阻抗方向元件的保护装置进行特性测度时应注意的问题,以SEL－321的相间距离保护为例,分析了距离保护静态动作特性及动态动作特性与测试方法及两者之间的关系。     

Static VAr compensator protection

Static VAr compensator (SVC) protection practices are presented. Protection schemes comprise a combination of conventional protective relays as well as protection functions performed by the control system. This paper describes different protection functions applicable to SVCs and includes a tabulated overview of possible SVC protection methods. A section is dedicated to testing SVC protection systems. The outlined test procedures may be adopted when commissioning new installations in order to demonstrate proper protection operation. Finally, an important aspect of SVC protective schemes is related to the interactions with transient overvoltages, harmonics, short-circuits, and geomagnetic induced current (GICs) of the transmission network. This paper discusses these issues and identifies areas where careful protection considerations are required     

Dynamic testing of frequency relays

Frequency relays are often applied on power systems either to protect generation equipment or provide load shedding capabilities. Accurate setting and operation of these relays is essential in the proper coordination of the power system equipment. Dynamic testing provides a method of assuring the proper operation of frequency relays. Along with this testing is a myriad of complexities and confusion. Dynamic tests are not always as straightforward as one might think, especially when the results are not as anticipated. The methods of testing, type of test equipment used, and the specific relay measuring techniques all play a significant role in the dynamic testing results. This paper discusses the intricacies of dynamic frequency testing along with the differences between test equipment and frequency relays and how these differences affect the testing results. A sampling of four frequency relays was tested (three solid-state devices and one electromechanical), each using four different test sets. Results of each are discussed     

The Impact of Sine-Wave Distortions on Protective Relays

Sine wave distortions on power systems are shown to affect the performance of both electromechanical protective relays of classical designs and static relays of various designs. Digital based (computer) relay systems do not circumvent, per se, wave distortion problems. Protection relays are shown to not respond to any single parameter such as the rms value or the fundamental component, of an applied signal. It is noted that there are no wave distortion performance standards nor waveform testing standards for protective relays, other than for harmonic restraint relays. This can be attributed to the lack of recognizing as a significant factor the causal relationship between relay performance and waveform distortion. This is an interim report constituting about 20 percent of a contemplated special report, "Sine Wave Distortions on Power Systems and the Impact on, Protective Relaying". A bibliography on the larger subject is included.     

Lessons Learned Through Commissioning and Analyzing Data From Transformer Differential Installations

Ensuring correct setting and installation of a transformer differential relay is critical. A transformer differential relay must detect internal faults, damaging overloads, and through-fault currents while remaining secure against misoperation. The ability to use wye-connected current transformers with microprocessor-based relays has simplified installations, and these relays provide better commissioning tools than those available with traditional relays. However, installations and commissioning remain complicated. Installation and settings errors continue to be widespread, implying a need for more rigorous commissioning tests. Even with greater commissioning effort, occasional wiring problems develop over time, and these can best be resolved through analysis of relay event-report data. In the interest of reducing transformer differential misoperations, we share in this technical paper practical lessons we have learned through experience with commissioning and relay event-report analysis.      

Microprocessor-based protective relays

This article describes the benefits of microprocessor (μP) relay performance and its capabilities beyond previous protective relaying technologies. This article also discusses a multiple quality-measurement approach to observing, measuring, and then calculating μP relay reliability and unavailability. This is an important consideration for industrial and commercial facilities that are being required to repair or replace old electromechanical or solid-state (analog and digital) protective relaying equipment because of equipment malfunctions, misoperations, accidental tripping, or obsolescent parts. Although lP relays have been commercially available for more than 20 years and researched for the past 40 years, industrial and commercial plant engineers tend to be more reluctant to embrace the μP technology. Electric power utilities in North America have aggressively selected to replace older protection equipment by upgrading and replacing the equipment with new μP relays whenever and wherever possible.     

Experience of numerical protective relays operating in an environment with high-frequency switching surge in Japan

This paper intends to provide general information about the experiences of numerical relay operation under many different kinds of surges from switchyards in Japan. The main focus of this paper is to investigate the immunity of numerical relays against a switching surge with relatively high frequency in a gas-insulated substation that is considered to be severe for the relay's correct operation. It is concluded that the reliability of today's numerical relays in Japan against the switching surge is almost sufficient due to the effectiveness of the immunity test standard adopted and countermeasures against the switching surge in Japan.     

General approaches to efficient d-q simulation and model translation for synchronous machines: a recap

This paper summarizes some recent findings in the area of synchronous machine modeling by means of equivalent circuits of arbitrary order. This allows us to propose a concise analytical expression to be derived for the admittance matrix and yields a structure of the state matrices which facilitates their numerical evaluation. By organizing the parameters into two structured vectors, we show how to calculate the state matrices and admittance matrix of generalized models of machine by means of MATLAB programs. The techniques are proposed for passing from the equivalent circuits to the operational impedances and vice-versa. Lastly, we transpose the conventional electromechanical state equations into our generalized modeling framework and derive new formulas for the matrices used in the eigenvalue analysis of synchronous motors and generators. Besides conventional stability studies, the present approaches along with the MATLAB toolbox could be useful for machine-converter system optimization, motor starting problems, digital TNA implementation and machine models identification. The latter application is investigated in particular with a view to enhancing current methods used to analyse short-circuit oscillograms recorded during the commissioning of large utility grade generators and synchronous condensers.     

比例制动和增量比例制动差动继电器的性能比较

比例制动差动继电器和增量比例制动差动继电器在电力系统母线保护中都得到了应用 ,这两种继电器既有共同点 ,又存在一些差别。本文就这两种差动继电器原理和特点加以分析和比较 ,以便电力系统选用时有一个比较明确的概念     

Benefits of upgrading: paper mill generator protection

There are a number of functional protection areas on paper mill generators 20 years or older that have significant shortcomings when compared to current IEEE recommended generator-protection practices. This article identifies these protection areas and the risks of not addressing the shortcomings. It also points out the advantages of using multifunction digital relaying to upgrade generator protection as a technology that offers many advantages over older electromechanical relays. The completed upgrade project at MeadWestvaco's Luke Mill in Maryland provided a number of examples of these benefits in uncovering mill problems that, if they had gone undetected, could have resulted in costly mill shutdowns or damage to mill generators.     

The new science of protective relaying in the petrochemicalindustry

The multifunction digital relay has greatly expanded the science of protective relaying. The new science of protective relaying has resulted in the following improvements and benefits to the petrochemical industry. The multifunction relays typically have a large array of functions that can be used for electrical equipment protection. The multifunction relays are typically less costly than the equivalent package of discrete electromechanical and solid state relays. The programming logic provided by most multifunction relays allows for sophisticated protection schemes that were either not possible or economical with the discrete protection components of the past. The burden requirements of the multifunction relays are typically very low. With increases in technology, the testing and calibration of protective relays is changing. Advances in technology in the future may result in a decreased life expectancy of protective relay packages of the future     

Comprehensive transmission distance protection settings using an intelligent-based analysis of events and consequences

This paper introduces a new methodology for settings of transmission system distance protection based on an intelligent analysis of events and their consequences. The output of the proposed methodology is comprehensive distance relay settings which include not only the zone reaches and zone time delays, as in the existing approaches, but also the optimal impedance operating characteristics, the fault detection settings, and the required relay sensitivities in terms of voltage and current. The need for this methodology is the result of the increased complexity of interconnected power systems protected with a large number of relays with different relay technologies, such as electromechanical, static, and numerical as well as diversity in their operating algorithms. The relay settings are automatically updated after every major change in the state of the network topology. Since it is not possible to include all design details of the proposed system, sample design events and rules are given to illustrate the proposed methodology.     

The safety matrix-a method for guidelining industrialmicrocomputers

A matrix guideline, used to compare the safety values of existing control circuit options to those of new options, is outlined. Programmable controllers, instrument distributed control systems, front-end controllers, and microcomputers are compared to electromechanical relays to clarify the microcomputer type controllers' levels of safety responsibility. The matrix can assist those knowledgeable in safety and electromechanical relay application, but not familiar with today's microcomputer technology, in choosing the appropriate system configuration for risk-related applications     

Applying the directional neutral, 67N, function in microprocessor multifunction relays

This paper is a case study of the application of the 67N function in a digital multifunction relay. The directional neutral current relay, function number 67N, is often found to be critical to the proper operation of a protective scheme. Furthermore, a false trip of a 67N will usually be devastating. The 67N is a complex function that always required more wiring than almost any other relay. The 67N is now available as one of many functions in digital multifunction relays. However, the digital 67N may be even more difficult to set and test than it was as a single function in an old electromechanical relay.     

IEC 61850数字化保护动模测试系统设计与实现

IEC 61850标准的应用给变电站自动化系统带来了重大变革。在此类变电站中,保护装置可以直接从电子式互感器处获取所需的电流、电压数字量信息,并向智能开关控制器发送数字化跳闸命令。这种数字化保护与传统的微机型保护在硬件结构和信号处理方面都存在差异,传统的保护测试方法将不再适用。文章分析了基于IEC 61850的数字化保护装置的测试要求,提出通过对传统的物理模拟系统进行升级改造,建立符合要求的测试系统。根据这一思路,该新型测试系统在山东大学电力系统动态模拟实验室的基础上开发而成。初步试验结果表明,测试平台能够提供所需要的二次接口特征和测试环境,可以对不同种类的IEC 61850保护装置进行动模测试。     

SEL 微机保护在变电站综合自动化系统中的应用

介绍SEL微机保护应用于梅州扶大110KV变电站综合自动化系统中的情况,阐述了主要特点、设计调试过程中遇到的问题和解决方法,指出该种微机保护功能完备,符合变电站自动化要求。