Protective Relay Testing Research Articles

Real-time RMS-EMT co-simulation and its application in HIL testing of protective relays

This work proposes an interfacing technique that uses the built-in three-phase transmission line models available in simulation platforms to perform Root Mean Square (RMS)- Electromagnetic Transient (EMT) real-time, multi-domain and multi-rate co-simulation. The main objective of this paper is to show the application of this kind of simulation in hardware-in-the-loop (HIL) testing of protective relays. Two well-known platforms are considered in this work: OPAL-RT with its ePhasorSim tool is used for RMS simulation, and RTDS is used for EMT simulation. However, the proposed technique is sufficiently general to be applied to other real-time simulation platforms that have similar built-in transmission line models. To convert waveforms to phasors, a non-buffered rapid curve fitting method was implemented to attend to real-time constraints. During the testing phase of this research, tests for the HIL were completed using an actual transmission line protection relay. The presented results of tests highlight the benefits of the proposed interfacing technique.

Development of Railway Protective Relay Simulator for Real-Time Applications

Electric railways use a single-phase system, with the line comprising a trolley wire (TF) that supplies power to the load with a neutral wire and an autotransformer (AF) feeder to absorb the return current of the rail. Testing the performance of the protective relay that detects the fault of the traction power-supply system (TPSS) and operates the circuit breaker is very important. Until now, the performance test of protective relays for the TPSS has been conducted via a simple-steady test or using an expensive real-time simulator. However, under a fast-moving environment in which the load consumes a large amount of power, the protective relay must always detect faults and operate properly. This paper proposes a digital simulator that enables the dynamic testing of protective relays without using any steady test and expensive real-time simulators. This simulator includes both external waveform import and internal waveform generation functions. Users can test the operation of the protective relay by entering the waveform generated externally or internally into the protective relay. Additionally, it has the ability to monitor the operating protection elements and pickup time when the protective relay detects a fault and orders the circuit breaker trip.

Design and Analysis of Amplifiers for Protective Relay Testing

Design and Analysis of Amplifiers for Protective Relay Testing

Protective Relay Tests of Hybrid SFCLs in a Korean Distribution Power System Using RTDS

A study on protective relay systems is one of the important technical issues concerning power systems that use Superconducting Fault Current Limiters (SFCL). We used a Real Time Digital Simulator (RTDS) in order to study the true interaction of the protection system with the power systems. RTDS modeling of SFCL is necessary to obtain detailed protective relay tests. In this paper, we developed an analysis model using RTDS in order to study the transient behavior of a 22.9 kV hybrid SFCL and performed closed-loop testing on a protective relay in a distribution power system using the developed SFCL model. The model uses an operation mechanism of the real SFCL. The 22.9 kV hybrid SFCL is under development by LSIS (LS Industrial Systems Co., Ltd.) and KEPRI (Korea Electric Power Research Institute) in Korea. The parameters of the model are based on the test data from the real SFCL. Power system planners and operators will be able to solve the problems that are expected in the application of SFCLs to power systems by using these protective relay testing results.

High current low ratio

This article is one of the few references describing high current testing of protective relays using low ratio current transformers (CTs). Maximum fault currents on power plant auxiliary buses are routinely 40 kA and can be as high as 80 kA. Accurate measurement of high-current magnitudes requires high-ratio CTs. The rests show the limitations of Fourier and cosine filters used in microprocessor relays that extract the fundamental phasors and eliminate harmonics. The tests validate the operation of a cosine-peak adaptive filter designed to cope with the highly distorted saturated waveforms produced by the low-ratio CTs subjected to high current. The details of relay operation are shown in unfiltered event records of the test cases. This article reports on the results of primary high-current tests of overcurrent, motor, and distance relays using low-ratio CTs. The test currents ranging from 6-50 kA were used with CTs with ratios of 50:5, 300:5, and 600:5. This article compares the internal unfiltered event records with MATLAB simulations.

Protective relay testing and characteristic analysis for high impedance faults in transmission lines

Abstract This paper describes the relay testing method and the results for detecting availability of protective relays under high impedance faults (HIFs) in transmission lines. Mho type distance relays, quadrilateral type distance relays and PCM type current differential relays are selected for relay testing. Four kinds of model power systems including actual power systems to be used for relay testing are established in PSCAD/EMTDC. Each protective relay is tested using RTDS and RTPS. The boundaries of each operating zone are surveyed by testing. Availability of HIFs detection on each relay are compared to each other. Impedance variation characteristics at the relay point are investigated using EMTDC in the case that source zero sequence impedance and load impedance are varied. The results shown in this paper can be used as an effective reference to install protective relays in real power systems.

Automatic test system advances transformer protection

In the last 10 years, computers have become part of every aspect of power system protection engineering. Multifunctional microprocessor-based relays with increasing complexity require the development and application of sophisticated computer software for the analysis, setting coordination, data acquisition and testing of such intelligent electronic devices (IEDs). Their functionality is modular and, at the same time, very specialized, as required by the protected substation or power system equipment. Conventional methods and test devices used for the testing of electromechanical protective relays are no longer adequate for the testing of advanced microprocessor relays.

The new science of protective relaying in the petrochemical industry

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.

Design and evaluation of a circulating current differential relay test system

This paper describes how an EMTP-based simulator can be used in conjunction with a relay test set to type-test a protection relay operating within a circulating current differential protection scheme. The combination of a simulator and a test-set is designed to replace a high power synthetic test plant that has been used for more than 30 years for type and approval testing of differential protection relays. The paper includes results that describe the operating performance of the new test system, on both internal and external faults, and these are compared with experimental results obtained from an identical set of tests on the synthetic test plant.

Optimized relay testing systems

With the appearance on the market of electronic test equipment that is controlled by software from personal computers, automation of classical test methods has been achieved and new methods have been developed. For engineers and technicians in charge of performing integrity and application tests, steady-state and dynamic tests can provide helpful information used in design, commissioning and preventive and corrective maintenance. These test methods result in savings of time and the cost involved in these tasks. Since 1990, the Spanish electric utility, Iberdrola, and the Electrical Department of the University of the Basque Country have been developing tools to: automate protective relay testing; analyze the location and characteristics of faults in the power network on the basis of oscillographic records; and simulate real or hypothetical fault conditions on a protective relay in order to monitor its behavior. Two automatic relay testing systems and experience of their use are introduced in this article. Particular testing protocols of different relays are incorporated and all useful features available to increase the automation grade are considered. Both systems minimize power system protection relay maintenance times and costs and improve the quality and reliability of relay management.

Modular simulators match cost and performance criteria [power systems

Digital power system simulators for protective relay testing were introduced as a concept in the late 1970s with the first designs made available in the early 1980s. Since that time, a variety of digital simulator solutions have been implemented and used by utilities, universities, and relay vendors. It is interesting to note that all of the designs had quite different implementation approaches and performance characteristics. This article features a new concept for a modular digital simulator design in which a variety of hardware and software modules have been developed and used to configure different simulator solutions. The author describes how modular digital simulator configurations range from low-cost single-user, to multiuser environments for open-loop testing and real-time application.

Digital simulators expedite relay performance evaluation

This article looks at the various applications of digital simulator technology that have been used to meet the testing requirements of today's more advanced power system protection relays. The authors describe how digital simulators present a new development tool for real-time simulation techniques and for the automation of protective relay testing.

Use of modern waveform reconstruction techniques in digital power system simulators

This paper presents a short tutorial covering the use of modern waveform reconstruction techniques in digital power system simulator applications. Special emphasis is given to the requirements related to open- and closed-loop testing of protective relays and the possibility of using existing standards regulating digital audio applications.

Closed-loop testing with the real-time digital power system simulator

Most protection and control equipment is usually tested in the open-loop mode. However, closed-loop testing is often the only cost-effective approach. This paper highlights the areas where closed-loop testing of protective relays and control equipment is preferable. Test setups with a real-time digital simulator for closed-loop testing of protective relays, power system stabilizers, and controllers for controlled closing of individual poles of a shunt capacitor breaker are described.

Design, implementation and validation of a real-time digital simulator for protection relay testing

This paper presents implementation details describing a new design of a real-time digital simulator for relay testing. The simulator is developed under requirements to utilize, as much as possible, low cost commercial computer hardware and system software support. The other requirements ask for a three-terminal support with extensive graphical user interface (GUI) and a simulation time step as low as 50 /spl mu/s. Such a design has been built for Western Area Power Administration (WAPA), USA, and fully validated using a model of an actual WAPA power system section. The simulator was delivered to WAPA in March 1994.

Real-time digital simulator for protective relay testing

The Western Area Power Administration (WAPA) recognized that real-time testing of protection relays is needed for a full evaluation of different relaying products considered for future use on the WAPA system. In terms of protective relaying, some important sections of the WAPA system have introduced several real challenges in deciding which relaying product will best suit the given application. The relaying applications are quite complex, consisting of parallel lines with series capacitor compensation, MOV protection on the capacitors, and a single-pole reclosing scheme. The authors describe how WAPA implemented a new low-cost, high-performance digital simulator design aimed at providing real-time operation while preserving accuracy and flexibility. >

Transients computation for relay testing in real-time

This paper discusses characteristics of a new digital simulator for protection relay testing. The most demanding design requirement is computation of fault transients under the condition of real-time change of power system configuration due to relay operation. This problem is solved using EMTP computational techniques enhanced with novel numerical solutions for dynamic power system configuration change and nonlinear element modeling. An advanced computer architecture is utilized to achieve further optimization of the execution time for the transients computation code. The main advantage of this design is the use of conventional single processor computer architecture in combination with advanced digital signal processors (DSPs). This makes this simulator an off-the-shelf product with all the benefits of commercially available computers priced at a relatively low cost. >

RETEX (RElay Testing EXpert): an expert system for analysis of relay testing data

An expert system which is applied to power system protective relay evaluation testing is described. An expert system called RETEX (relay testing expert) has been developed as a computer aid for analysis of relay testing data. A knowledge base for relay testing data analysis has been developed. A relay logic model is used to determine the expected relay operation for simulated faults. Hierarchical test reports and comparison reports can be automatically generated by RETEX, which is designed with basic language processing capabilities. The generality necessary for handling various relay models is provided by a description file approach. The expert system is implemented in a rule-based and object-oriented architecture with the expert system development tool NEXPERT Object.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Automated testing of power system protection relays

Regular testing of protection relays is vital to maintain the integrity of electrical power transmission and distribution systems. Until recently, such testing was time consuming and required a high level of engineering skill. New developments in automatic relay test sets allow more efficient deployment of skilled personnel and permit more frequent testing which will lead to an overall improvement in power-system operational reliability. The authors describe the requirements for automatic test facilities and then go on to discuss hardware, software, and test routines. Test results and field experience are described.< >

Current injection test. New technology for old?

The testing of protection relays on the electricity supply network has changed little over recent years. The test itself is unlikely to change, as it is both reliable and well proven, but the way that test equipment to perform the tests is changing is the subject of this article