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Protective Relay Engineers, 2004 57th Annual Conference for

Date 1-1 April 2004

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Displaying Results 1 - 25 of 27
  • Table of contents

    Publication Year: 2004 , Page(s): i - ii
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  • A review of ferroresonance

    Publication Year: 2004 , Page(s): 1 - 29
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    This article covers the basics of a ferroresonant condition: the network circuits involved; two simple analysis processes - linear circuit analysis concept and dual X/sub M/ analysis concept. A review of how ferroresonance is prevented and a variety of other issues were discussed. View full abstract»

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  • Some observations on bus relaying

    Publication Year: 2004 , Page(s): 30 - 45
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    The literature is replete with guidance on the subject of bus relaying. Because of the extremely detrimental results of incorrect operation of bus differential relaying, those giving such guidance have generally leaned in the direction of security. This paper is intended to point out the possibility of easing some of the useful, but not immutable restrictions that have been handed down from generation to generation. In general, the bus configuration does not dictate any particular bus differential relaying concept. Voltage level and importance of the circuits connected to the bus are far more significant criteria. Speed and cost are key factors. Current transformer location and quality are important ingredients in the choice of a bus relaying scheme. View full abstract»

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  • Applying distance protection to cable circuits

    Publication Year: 2004 , Page(s): 46 - 69
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    Protection of AC cable circuits creates few unique problems that are normally not encountered when protecting overhead transmission lines. This paper reviews types and main electrical characteristics of cables as well as protection techniques for AC cables, to finally focus on applications of distance protection. Simulation examples are included to illustrate the need for fault studies in order to fine tune settings and verify distance protection applications for cables. View full abstract»

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  • Working with high-tech customers on power quality issues

    Publication Year: 2004 , Page(s): 70 - 79
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    Austin energy has the opportunity to better serve its key primary customers by focusing on its customers' needs, improving power quality at its transmission and distribution levels, providing technical support and information, and establishing an open and honest daily interaction and communication with the customers. This paper discusses the power quality and reliability programs implemented by Austin Energy in both its transmission and distribution systems and the use of these programs by one of its industrial customers, Motorola. View full abstract»

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  • Understanding and reducing arc flash hazards

    Publication Year: 2004 , Page(s): 80 - 85
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    Recent changes in workplace safety regulations have heightened the awareness of hazards associated with electrical arcs. The hazard level must be quantified and workers properly protected before entering proximity of exposed energized conductors. The evolution of safe work practice standards has spawned significant research into the characteristics of and energy within an electrical arc. This article presents some ways of protection and safety for the workers due to electric arc flashes. The 2000 edition of NFPA 70E presents and opportunity to re-examine the electrical system and procedures and gain a better understanding of potential weaknesses. Employee safety can be improved, thereby reducing the financial risk to the company. View full abstract»

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  • Distribution incipient faults and abnormal events: case studies from recorded field data

    Publication Year: 2004 , Page(s): 86 - 90
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    A typical distribution circuit consists of thousands of individual components, from transformers to switches to insulators. Failure of a single component can cause service quality and reliability problems for the entire circuit and even adjacent circuits. Under the sponsorship of the Electric Power Research Institute (EPRI), and with the cooperation of EPRI utility members, researchers at Texas A&M University have put in place an advanced, multi-site monitoring system. This system instruments dozens of circuits at multiple utility company substations across the United States and Canada. Extensive data from this multi-site monitoring system have documented numerous examples of incipient fault behavior preceding component failures. View full abstract»

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  • Distribution automation to improve circuit reliability

    Publication Year: 2004 , Page(s): 91 - 96
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    In an effort to improve system reliability, CenterPoint Energy has implemented an extensive distribution circuit automation program. By strategically placing automated devices on circuits with poor reliability performance or high customer counts, CenterPoint has achieved impressive results. This paper will describe the devices and some of the configurations used in our automation program and discuss some of the results we have seen. View full abstract»

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  • A novel approach for ground fault detection

    Publication Year: 2004 , Page(s): 97 - 109
    Cited by:  Papers (3)  |  Patents (2)
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    Faulted lines must be repaired and returned to service in the shortest possible time to provide reliable service to the customers. Fault detection is an important aspect of system protection, as it involves personnel as well as equipment safety. The research on fault detection techniques is mainly based on conventional methods, not suitable for detecting high impedance ground faults. This paper discusses a novel approach for detecting high impedance ground faults using state-of-the-art signal processing technology. Some laboratory test results are reported. The reported work offers promise in realizing dependable and secure high impedance ground fault detection using latest technology. View full abstract»

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  • Green power - wind generated protection and control considerations

    Publication Year: 2004 , Page(s): 110 - 131
    Cited by:  Papers (2)
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    Wind-generated energy systems have some unique challenges for protection and control engineers. The typical wind farm is not a new form of generation being interconnected to the bulk power system. The success of the evolving Green Power Interconnected Projects is very dependent on the following of a logical method used by electrical systems, leading to a long life for the assets and investments for the project. The protection and control aspects of the multifunction numerical devices enhance the ability to operate reliably and to maintain the project electrical systems for the life of the asset. Power system faults will happen, and analysis tools imbedded in the numerical systems assist the engineer to ensure that the protection operates as designed. This allows adjustments to be made, if necessary. This paper will address the following topics for a typical wind farm: wind turbine-generator protection and control; 34.5 kV distribution wind farm substation and feeders protection; wind farm transmission interconnection; monitoring, command and control of the wind turbines and the interconnection system; start up and commissioning of the wind farm and associated substations; unusual operating and maintenance experience. View full abstract»

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  • Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial power systems. Part 1 - the problem defined

    Publication Year: 2004 , Page(s): 132 - 138
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    The paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. View full abstract»

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  • Utility interconnection and plant distribution protection modernization

    Publication Year: 2004 , Page(s): 158 - 166
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    This case study documents power system reliability improvement achieved at an industrial gas processing plant using digital multi-function relays. It will review the power system protection schemes in-service at the utility interconnect, plant generation units and distribution feeder breakers. Utility separation techniques and negative sequence directional overcurrent elements are used to improve energy source selection and distribution system selectivity. The study describes protection programming that provides additional safety features and additional layers of equipment control. Methods to monitor electrical system disturbances and protection quality are presented. Derived conclusions show that multi-function microprocessor systems are capable of providing enhanced protection, control and monitoring. View full abstract»

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  • Implementation of automatic bus transfer scheme on multi-function microprocessor based relays

    Publication Year: 2004 , Page(s): 167 - 181
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    This paper presents the basic principle and a comparative analysis of the various automatic bus transfer schemes in practice and their applications in the industries and power plants. The prime objectives of this paper are as follows: the illustration of a flexible residual voltage automatic bus transfer scheme implementation using a multi-function microprocessor based relay, a study of its onsite-testing criteria, and finally the inferring of its common troubleshooting stages encountered in the real-world application. Use of the numerical IEDs are recommended for simplification of the automatic bus transfer system, component cost reduction and increased system reliability, and the availability of events for transfer analysis. View full abstract»

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  • Primary high-current testing of relays with low ratio current transformers

    Publication Year: 2004 , Page(s): 182 - 189
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    This paper serves as one of few references describing primary high-current testing of protective relays using low ratio current transformers. Accurate measurement of high-current magnitudes requires high ratio current transformers. However, it is the practice to apply low ratio CTs based on small motor loads. The protection engineer then relies on the motor relay to trip for the enormous current of a phase-to-phase fault in the motor cable. The assumption is that fault current exceeding 300 times the CT rating can produce a secondary current large enough for a fast instantaneous trip. This leap of faith is based on the lack of knowledge of the highly distorted secondary waveform and how it is processed in the relay. The tests 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. This paper also reports on the results of primary high-current tests of overcurrent, motor, and distance relays using low ratio CTs. Lastly, this paper compares the internal unfiltered event records with MATLAB/spl reg/ simulations of the same cases. View full abstract»

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  • Rebirth of negative-sequence quantities in protective relaying with microprocessor-based relays

    Publication Year: 2004 , Page(s): 190 - 219
    Cited by:  Papers (1)  |  Patents (1)
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    This paper focuses on the uses of negative-sequence quantities in protective relaying. The emphasis is on numerical relays since they have facilitated the calculation of symmetrical components. Negative-sequence quantities (the voltage and current denoted by V2 and 12) are very useful quantities in protective relaying. The simplicity in the calculation of these quantities in modern numerical relays has reinforced their use in the theory and methods used by current protective relaying devices. The paper begins with discussion of some implementations of negative-sequence filters in older relays. Next is a brief review of symmetrical components and an analysis of unbalanced faults in power systems. This review leads to a discussion of the characteristics of negative-sequence quantities and illustrations of how these quantities are used in protective relaying. Because the discussion generally involves symmetrical component theory, the paper makes references throughout to the other two symmetrical components (positive-sequence and zero-sequence). View full abstract»

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  • Tools and techniques for area relay coordination studies

    Publication Year: 2004 , Page(s): 220 - 246
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    The paper covers several of the tools and techniques used by a protection engineer in a methodology to test and document the qualities of an area's transmission line protection. The documents can be a useful "legacy" for use by others in the future. The tools described are generally available to the present-day engineer. These tools include word processors, electronic spreadsheets and specialized relay coordination software. The techniques used by this protection engineer are part of a skill set developed through association with other practicing engineers, through study of literature on the subject and through individual experience in practicing the profession. The bottom line of this paper is that the area relay coordination studies should not be taken lightly. It requires detailed and methodical approach. These studies can be beneficial to various organizations in the electric utility. View full abstract»

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  • Special considerations in applying power line carrier for protective relaying - IEEE power systems relaying committee special paper - relaying communications subcommittee, working group H9, 1-5-04

    Publication Year: 2004 , Page(s): 247 - 281
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    This paper discusses the considerations in applying power line carrier for protective relaying. The goal in using communications for protective relaying is to provide simultaneous high-speed clearing for all faults within a line section, including end-zone faults. A PLC channel can also be used to provide remote tripping functions for transformer protection, shunt reactor protection and remote breaker failure relaying. There are many references available that discuss PLC applications. IEEE 643 (IEEE guide for power-line carrier applications) is a particularly good reference. In the bibliography section of this paper, many other references are listed. The intent of this paper is not to cover the actual channel application but circumstances that can affect the performance of the protective relay system. Subjects such as a non-homogeneous line, the use of capacitors and reactors in the line, transformer-tapped lines, special protection applications, and the issue of non-licensure of PLC by the electric utility are covered. The intent of this paper is to document important issues that should be considered when applying a PLC channel to a protective relay system. View full abstract»

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  • Out-of-step protection fundamentals and advancements

    Publication Year: 2004 , Page(s): 282 - 307
    Cited by:  Papers (7)
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    Power systems are subjected to a wide range of small or larger disturbances during operating conditions. Small changes in loading conditions occur continually. The power system must adjust to these changing conditions and continue to operate satisfactorily and within the desired bounds of voltage and frequency. The power system should be designed to survive larger types of disturbances, such as faults, loss of a large generator, or line switching. Certain system disturbances may cause loss of synchronism between a generator and the rest of the utility system, or between interconnected power systems of neighboring utilities. If such a loss of synchronism occurs, it is imperative that the generator or system areas operating asynchronously are separated immediately to avoid widespread outages and equipment damage. In this paper we describe the philosophy and application fundamentals of out-of-step protection in transmission systems. We also discuss recent enhancements in the design of out-of-step tripping and blocking protection functions that improve the security and reliability of the power system. In addition, we demonstrate the out-of-step phenomena and distance relay element behavior using EMTP and Matlab simulations. View full abstract»

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  • New phase-segregated digital busbar protection solutions

    Publication Year: 2004 , Page(s): 308 - 338
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    This paper focuses on the new phase-segregated solution. A general overview of busbar protection principles is given starting from simple interlocking schemes for single-incomer distribution busbars, to high-end microprocessor based protection schemes. Also, a novel phase segregated approach based on existing hardware platforms capable of processing plurality of single-phase AC input signals is presented. The new solution is discussed in details including architecture, reliability, dependability, speed of operation, security on external faults, case of configuration and cost. Lastly, the basic application principles for protection of complex busbars are presented. They include a tie-breaker with a single CT, treatment of blind zones and overtripping zones, dynamic bus replica, end fault protection and breaker failure protection. Both principles and examples are presented. View full abstract»

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  • Verification of models in protection related analysis programs

    Publication Year: 2004 , Page(s): 339 - 349
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    The integration of multifunctional IEDs with protection, control, monitoring and recording functions in UCA 2.0 or IEC 61850 based substation automation systems results in the implementation of distributed systems for monitoring and recording in substations or power plants. Different types of abnormal system conditions at the distribution, sub-transmission and transmission levels of the power system have specific characteristic that are reflected in the requirements for their recording for model verification. The relays perform on-line analysis that immediately provides a fault summary report including the magnitude and angle of the fault currents and voltages, type of fault, fault location and other useful information for the operations and maintenance personnel. High- and low-speed disturbance records can be used for the verification of the models used for dynamic stability studies. Waveform records from advanced monitoring and recording devices are identified as the primary source in the process of verifying the models in electromagnetic transient analysis software. View full abstract»

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  • Pilot protection communication channel requirements

    Publication Year: 2004 , Page(s): 350 - 391
    Cited by:  Papers (2)
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    Pilot relaying has been applied for transmission line protection since the 30's. The well known communication channels (pilot wire or power line carrier) are increasingly being replaced by digital channels. Dark fiber (dedicated fiber optic cable), multiplexed fiber optic systems (T1 and SONET) and 56 kbps phone lines (DDS - digital data service) are now made available for pilot protection purposes. The new channels provide much higher data transfer rate but reliability and security performance criteria developed for the telecommunications industry are not easily translated to teleprotection applications. A number of new terms are introduced to the protection engineer and it might not be all that obvious what precautions need to be taken from a protective relaying point of view. This paper discusses the requirements for the communication channel for common pilot schemes, direct transfer trip and current differential relaying. It addresses issues such as channel asymmetry and channel switching in T1 and SONET networks and the affect on pilot relaying performance. It also provides basic description of digital communication techniques and terminology that the relay engineer may encounter in his work. View full abstract»

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  • Design and implementation of wide area special protection schemes

    Publication Year: 2004 , Page(s): 392 - 402
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    This paper discusses the drivers for implementing SPSs, the functional requirements of such systems including the interface and coordination with existing protection and control equipment, and the resulting design considerations such as system architecture, human machine interface (HMI), communication system robustness, performance monitoring, and system test (including commissioning, manual, and automatic test modes). View full abstract»

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  • Maximizing power system stability through wide area protection

    Publication Year: 2004 , Page(s): 403 - 418
    Cited by:  Papers (2)
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    This paper describes basic principles and purpose for applying wide area protection schemes, also known as remedial action schemes (RAS) or system protection schemes (SPS). In the areas of power system automation and substation automation, there are two different trends: centralization and decentralization. More and more dynamic functions are moving from local and regional control centers towards central or national control centers. At the same time we also observe more "intelligence" and "decision-power" moving closer towards the actual power system substations. Greater functional integration is being enclosed in substation hardware. This raises discussions concerning reliability (security and dependability). The main targets for this paper are to: (1) sort out the terminology used in this area; (2) describe different application areas and related requirements; (3) illustrate different design principles - "top-down", "bottom-up", hierarchy, flat, etc., for different applications; (4) identify similarities and differences between classic equipment protection and system protection -concerning philosophy as well as concerning product and system design; and (5) show the value of wide area protection; (6) illustrate the great breakthrough for wide area protection, since the introduction of synchronized phasor measurements, based on PMUs (phasor measurement units). View full abstract»

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  • Synchronized phasor measurement in protective relays for protection, control, and analysis of electric power systems

    Publication Year: 2004 , Page(s): 419 - 450
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    The advent of satellite-based time-keeping systems and advances in computer technology have made possible protective relay sampling synchronization within 1 μs. These relays can now provide synchronized phasor measurements that eliminate the need to have different devices for protection, control, and electric power system analysis for system-wide applications and traditional protection applications. System-wide applications have different sampling and signal processing requirements than do traditional protection applications. These different requirements normally are addressed with different devices, one device for each specific function. This paper proposes combining the aforementioned applications in a single device with a flexible signal processing system. The addition of synchrophasor measurement in a protective relay results in increased power system reliability and provides easier disturbance analysis, protection, and control capabilities than do approaches with different information sources. View full abstract»

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  • Comanche peak switchyard event

    Publication Year: 2004 , Page(s): 451 - 468
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    This article discusses the electrical fault event that occurred on the 345 KV line between Comanche peak and Parker switching station. This event was caused by the failure of the primary and backup relay systems to operate on Breaker 8040 at Comanche Peak due to high contact resistance that had developed in the CHC fault detector relay in each relay system. Both relays have been replaced. Also, the protective relaying integrity of all lines out of Comanche Peak has since been validated. The ERCOT underfrequency load shedding relay scheme operated as designed to minimize the loss of load and generation. Also, the 138 kV source from Stephenville remained secure to Comanche Peak to maintain the nuclear safety systems. The immediate response to the event by all parties was good. Service was quickly and safely restored to the switchyard. The portion of the relay system that failed was identified, corrective action was taken, and the units were returned to service. Oncor has determined what happened, determined why the failure occurred, and developed a plan of action to prevent a reoccurrence. View full abstract»

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