Protective Relay Settings Research Articles

Protective relay setting of the tie line tripping and load shedding for the industrial power system

Protective relay setting of the tie line tripping and load shedding for the industrial power system

Protection co-ordination: determination of the break point set

Modern power system networks are often multiloop structured. Co-ordinated setting of overcurrent and distance protective relays in such networks is tedious and time consuming. The complicated part of this problem is the determination of a proper minimum set of relays, the so-called minimum break-point set (BPS), to start the co-ordination procedure. The paper presents a new graph-theoretical method to determine a near-to-minimum or a minimum BPS. Using the lemmas of this method, the determination of a minimum BPS can be reduced and decomposed into subproblems. Owing to the efficiency of these lemmas, the presented method quickly achieves the result, even for large networks. Moreover, due to the simplicity of the method, it can be manually applied to the graph of each network. Since the presented lemmas are general, they can be applied to improve any method dealing with BPS determination.

Computer‐aided protective relay setting system for large power networks

AbstractThis paper introduces a protective relay setting system capable of handling a large network up to 10,000 buses. The remarkable features are such useful functions as network analysis (fault analysis, load flow calculation, zero‐sequence current calculation, etc.), relay operation simulation, and automated setting coordination tasks.Fault currents in the maximum and the minimum operation networks are calculated to examine the setting values. The protection zones are searched automatically along the network connection. Protection coordination tasks among the primary and the backup relays composed of different types of relays can be performed by the relay operation simulation.The system is built on an engineering workstation, which works in cooperation with other network operation support systems. Its graphical user interface helps every engineer to examine the relay setting using a variety of databases.

Development and implementation of a power system fault diagnosis expert system

This paper describes a fault diagnosis expert system installed at the Tohoku Electric Power Company. The main features of this system are careful selection of the inferencing input data, rapid inferencing, integration of the expert system with other systems in a practical structure, and the adoption of a domain shell. This system aims for improved practicability by using time-tagged data from circuit breakers, protective relays, and automatic reclosing relays in addition to the input data used in earlier systems. Furthermore, this system also uses data from fault detection systems that locate fault points within electric stations. This system uses an AI-specific back-end processor to perform inferencing rapidly. Additionally, this fault diagnosis expert system is interfaced and integrated with a restorative operations expert system, an intelligent alarm processing system, and a protective relay setting and management system. The authors developed and adopted a power system fault diagnosis domain shell to ease system development, and used the protective relay operation simulation function of a protective relay setting and management system for system verification. >

大規模系統の故障解析・動作検証機能を備えたリレー整定支援システム

This paper introduces a protective relay setting system capable of handling a large network up to 10,000 buses. The remarkable features are such useful functions as network analysis (fault analysis, load flow calculation, zero-sequence current calculation, etc.), relay operation simulation, and automated setting coordination tasks. Fault currents in the maximum and the minimum operation networks are calculated to examine the setting values. The protection zones are searched automatically along the network connection. Protection coordination tasks among the primary and the backup relays composed of different types of relays can be performed by the relay operation simulation. The system is built on an engineering workstation, which works in cooperation with other network operation support systems. Its graphical user interface helps every engineer to examine the relay setting using a variety of databases.

A knowledge based approach for setting protective relays in transmission networks

Abstract An expert system is developed to perform the setting of protective distance relays in high voltage transmission networks. The developed system accounts for the setting and coordination of the three normal distance stages as well as the overreach resetting stages. The system is implemented in Prolog and features backward chaining reasoning with a hybrid rules and frames knowledge base. An efficient and flexible method is demonstrated for implementing frame based knowledge, which allows for inheritance and procedure attachment. The developed expert system can be used to set protective distance relays in transmission networks having arbitrary complex interconnections.

Graphical coordination program aids system relaying at Consumers Power

Consumers Power Company, an investor-owned, combination (gas and electric) utility serving customers throughout most of Michigan's lower peninsula, is in the process of adding a 345/138 kV autotransformer bank, rated 300 MVA self-cooled, to one of its substations. Before a system modification of this scale can be completed, protective relay settings throughout the area must be reviewed. Consumers Power Company's experience using the coordination graphics module to review settings for the planned system change and determine new settings to provide the required coordination is reported. The coordination analysis of overcurrent and distance devices is described. >

An expert system for protective relay setting of transmission systems

An expert system for setting protective relays in a high-voltage transmission system is proposed. Multilevel frames are used to represent relay specifications and system information. Setting rules are stored in the hierarchical rule base. The frame-based inference mechanism is adopted for an efficient integration of framework and rule. An easy system modification environment is achieved through predefined predicates and a frame editor. The use of the system would expedite the relay setting process with increased accuracy and consistency regardless of the power system's complexity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Interactive Computation System for Relay Setting and Simulation or Relay Operation in a Large Scale EHV Power System

This paper explains the interactive computation system for setting for the main and back-up protective relays used on the 500 kV and 275 kV power systems of the Tokyo Electric Power Co.. The object of the interactive system and the major calculations involved in the main protective relay setting and relay operation simulation are described. For the main protective relay setting calculations, this paper explains the basic theory and methods of relay setting; and in the relay operation simulation, it explains the basic theory, function and methods of calculation as well as the man-machine interfaces.

Comprehensive consideration of transient frequency deviations in power-system transient-stability studies

Recent studies which have considered separately the influence of transient frequency deviations on the various components of power systems subjected to transient disturbances are integrated, with the resulting development of a comprehensive computer program which takes full account of frequency dependence of all systems components and allows a more complete assessment of system performance than has hitherto been possible, The program can readily incorporate existing refinements of representation. Two realistic power-system problems illustrate the nature and variety of the system behaviour when frequency dependence is included, indicating particularly that overall negative damping may be present in some systems. Even when damping is positive, as is more usual, it may still be unsafe to neglect its influence as, although stability assessment appears conservative, voltage and current distributions in the network are erroneously predicted, and problems may be caused by the protective-relay settings based on these predictions. Although the computing time required to treat a system with full frequency dependence included is substantially greater than that for conventional calculations, the extra calculating cost seems warranted by the increased accuracy of calculation.

Novel Test Circuits for Protective Relays

IN THE TEST, calibration, checking, and setting of protective relays, and in the determination of their characteristic operating curves, it is of course necessary to apply to the relays the quantity or quantities which are expected to operate it. Problems are sometimes encountered in obtaining suitable test facilities, particularly when two or more variable a-c quantities are involved, and the phase angle between the quantities must be known or controlled. The solution to such problems generally may be obtained in the laboratory by special circuits and equipment.

Sensitive Ground Relay Protection for Complex Distribution Circuits

Protection engineers always have desired to obtain a system of ground fault protection that will discriminate and actually trip out only the ground faulted circuit of a complex distribution network. This has been a difficult chore because the magnitude of the ground current often varies so greatly as to be out of the range of the normal protective relay settings. A system is proposed here that not only has proper discrimination, but also operates on very low amounts of ground current with the maximum ground current held to such a low value that practically no harm or damage is done by the ground fault. This development was encouraged by the necessity of joint use of poles by lines of communication circuits and distribution circuits. This method comprises the installation of a small bank of grounding transformers at each of the stations where the lines originate or terminate. With these small ground banks the maximum ground fault current is very small. Adequate relays and systems are used to isolate only the faulted sections of line. The installation of one 11-kv and one 16.5-kv loop will be described. These two systems have had several years of successful operation.