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Protective Relay Engineers, 2012 65th Annual Conference for

Date 2-5 April 2012

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Displaying Results 1 - 25 of 49
  • [Front cover]

    Publication Year: 2012 , Page(s): c1
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  • [Title page]

    Publication Year: 2012 , Page(s): i
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  • [Copyright notice]

    Publication Year: 2012 , Page(s): ii
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  • Foreword

    Publication Year: 2012 , Page(s): iii
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  • [Blank page]

    Publication Year: 2012 , Page(s): 1
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  • Table of contents

    Publication Year: 2012 , Page(s): v - viii
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  • CCVT transient fundamentals

    Publication Year: 2012 , Page(s): 1 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (781 KB) |  | HTML iconHTML  

    Potential transformers and coupling capacitor voltage transformers (CCVT's) have been used successfully for providing voltage to the inputs of meters and relays since the 1960's. At voltage levels above 138kV economics dictate that CCVT's be used to provide secondary voltages to relays. As we'll see later CCVT's consist of a capacitive voltage divider along with a step down transformer and other associated equipment. Placing capacitance in series and shunt to the natural inductance of the power system leads to resonant circuits and RC time constants that affect the faithful reproduction of the primary voltage on the output terminals of the CCVT. These transients weren't a problem for electromechanical relays, but with the advent of faster solid state relays and modern microprocessor relays CCVT transients became a problem that needed attention. This paper will discuss coupling capacitor voltage transformer design. What factors in the design influence the transient behavior of the CCVT. What factors in the power system contribute to the transient behavior of the CCVT. How CCVT transient behavior affects relay performance. Finally, how relay manufacturers take this transient behavior into account in relay design. A Capacitive Voltage Transformer (CVT) is a CCVT without carrier accessories. The paper will use these terms interchangeably. Even though there is a slight difference between the two, the portion of the device in that pertains to the transient response is the same. View full abstract»

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  • Using synchrophasor for fault location identification

    Publication Year: 2012 , Page(s): 14 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (395 KB) |  | HTML iconHTML  

    Recent years have witnessed great improvements in the synchronized phasor measurement unit (PMU) technology. Synchronized measurements of the power system provide insightful data that was not visible prior to having PMU technology. As this technology continues to improve and as its infrastructure continues to grow, more PMU measurement locations are added every year. However, there are still many utility companies with very few synchrophasor points on their systems. Digital relays provide an economical source of these measurements since many relay manufacturers include PMU capabilities in their relays. This paper examines a method to locate faults on transmission lines without having PMU measurements on every bus and branch in the system. Test cases and real fault data is used to examine this method. View full abstract»

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  • Everyday modern protective relay engineering applications: Review of interesting electric power utility events, challenges, & concerns

    Publication Year: 2012 , Page(s): 22 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2121 KB) |  | HTML iconHTML  

    Over ten years have passed since CenterPoint Energy (CNP) began deploying modern micro-processor based protective relays across the utility's Houston, Texas electrical power service area. During the transition and service tenure of the modern relay devices, a variety of protective relay events and protective relay system design issues have been identified, analyzed, and resolved by CNP engineers. The most notable and interesting of these events and design issues will be detailed with a description of the situational information and the deliberation process behind CNP's methodology choices. Addressing these situations in this type of forum is advantageous for multiple reasons. For one, to build awareness of the existence of little recognized, however critical details. Another benefit is sharing protective relaying scenarios with a group of peer protection experts and employing their capability to improve future protective relay practices. Lastly, it is an interesting glimpse into the detailed, day-to-day work being performed within the electric power utility system protection industry. View full abstract»

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  • Distribution feeder caused wildfires: Mechanisms and prevention

    Publication Year: 2012 , Page(s): 43 - 51
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (479 KB) |  | HTML iconHTML  

    Drought conditions in the United States in recent years bring increased attention to the age-old issue of power line-caused fires. It has long been known that power line faults and failures can cause wildfires through multiple mechanisms. Failure mechanisms of various apparatus and operational conditions that result in wildfire ignition are reviewed. Case studies of faults and failures from operating utility systems are presented, along with a discussion of how these faults and failures represent competent sources of ignition for wildfires. Methods of preventing power line-caused wildfires are discussed. View full abstract»

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  • Wide-area Ethernet network configuration for system protection messaging

    Publication Year: 2012 , Page(s): 52 - 72
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB) |  | HTML iconHTML  

    Faced with demands on its transmission grid from new generation providers, SCE is now deploying its Centralized Remedial Action Scheme (C-RAS) - among the largest wide-area control systems applied to an electric transmission grid anywhere. The C-RAS architecture is the prototype for future wide area monitoring, protection, automation, and control (WAMPAC) systems that collect data from across the grid to carry out the full range of utility transmission control functions, including those with high speed and mission-critical reliability. C-RAS uses Ethernet networking and IEC 61850 GOOSE messaging for flexibility, scalability, speed of operation, and inherent performance monitoring. Wide area application is beyond the original intended application of GOOSE, and requires special attention to the arrangement of the Ethernet network paths to assure fast, reliable, secure transmission. The paper has described how the communications infrastructure has been designed and configured to meet C-RAS requirements. Experience from C-RAS development may be helpful for other industry applications of IEC 61850 GOOSE messaging between sites connected by a WAN link. The first phase of C-RAS will be fully deployed in 2014. Over the years of C-RAS growth, ongoing relay development will bring implementations of new services using the protocol of IEC 61850-90-5, which is specifically designed for applications like C-RAS and can be incrementally phased into individual substations and communications links. View full abstract»

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  • CVT transients revisited — Distance, directional overcurrent, and communications-assisted tripping concerns

    Publication Year: 2012 , Page(s): 73 - 84
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1223 KB) |  | HTML iconHTML  

    Several classic papers explain the fundamentals of capacitive voltage transformer (CVT) design, operation, and transient response. Distance elements can overreach, particularly in high source-to-line impedance ratio (SIR) applications, which can result in undesired Zone 1 operations. Because this continues to be a problem in real applications, this paper revisits documented field cases using event data in hopes of shedding new light on this known problem. Solutions to distance element overreach are shared, from modified reach and time delays to modern solutions such as CVT transient detection logic. How does the protection engineer know what type of CVT is used? How can the protection engineer calculate the SIR from real-world event data? This paper gives practical guidance for the user to answer these fundamental questions. New data and research included in this paper update the topic. We investigate the CVT transient effect on directional element stability, directional overcurrent applications, and various communications-assisted protection schemes. We also share field cases of directional element and directional comparison blocking scheme misoperations and solutions and practical recommendations for mitigating the problems in all cases. View full abstract»

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  • An adaptive HV transmission lines reclosing based on voltage pattern in the complex plane

    Publication Year: 2012 , Page(s): 85 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2179 KB) |  | HTML iconHTML  

    Transient single-phase short circuits are the most common transmission line faults. The short circuit arc of a transient fault is usually self-extinguishing after opening the line circuit breakers. High-speed single-phase reclosing of transmission line can help to improve system stability. Employing a pre-set reclosing interval may pose problem if the time interval is not sufficient to fully deionize the fault arc. It is desirable to have adaptive reclosing interval and fast detection of arc extinction, which could facilitate successful high-speed reclosing of transmission line and bring benefit to the system stability. A new adaptive reclosing algorithm is proposed in this paper. It uses the pattern of the faulted phase voltage in the complex plane to distinguish between transient and permanent faults and is also able to detect the time when the arc is extinguished. Theoretical analysis is provided to support the technique. In addition, the performance of the proposed technique is verified using a recorded field data from 765 kV transmission line and several cases simulated in EMTP including detailed arc and CVT modeling. View full abstract»

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  • Backup considerations for line current differential protection

    Publication Year: 2012 , Page(s): 96 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    Line current differential (87L) protection relies on communications for the exchange of current values and, if applied over asymmetrical channels, on external time sources for current alignment. Proper engineering of 87L schemes calls for a backup strategy that considers the loss of communications and/or the loss of external time sources. This paper reviews various channel and time backup strategies for 87L protection schemes and considers utility practices and regulatory constraints related to line protection redundancy, forced line outages, preferred balance between protection dependability and security, ability to provide adequate protection coverage with distance or overcurrent elements, and availability of an independent pilot channel for directional comparison backup schemes. View full abstract»

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  • Do system impedances really affect power swings — Applying power swing protection elements without complex system studies

    Publication Year: 2012 , Page(s): 108 - 119
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1887 KB) |  | HTML iconHTML  

    One of the traditional techniques for detecting power swings uses a dual-quadrilateral characteristic. It is based on the measurement of the time interval it takes the positive-sequence impedance to cross two blinders. Another technique monitors the variation of the swing center voltage approximation. This paper presents a performance comparison between applications of these two techniques in cases derived from a sample network transient simulation and in cases recorded during real operations in the field. View full abstract»

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  • 500kV IPT breaker failure protection: An application of dual timer scheme for short critical clearing time

    Publication Year: 2012 , Page(s): 120 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (405 KB) |  | HTML iconHTML  

    Circuit breaker failure protection scheme is typically used in electric transmission system to provide backup protection against any fault occurring at any given time in case a circuit breaker fails to open following receiving a trip signal from system protection relays. An ideal breaker failure protection system should clear the fault by operating the least amount of contributing breakers, both locally and remotely, within a desired time frame that does not cause the system to become unstable. In general such scheme can be applied with proper timing coordination including safety margin before approaching the system critical clearing time. A system critical clearing time is defined as the time duration that a fault can remain on the system before system instability occurs. In Progress Energy Florida, a system planning study for a future scenario recommends its 500kV transmission system critical clearing times to meet 8 cycles for single-line-to-ground fault and 5.5 cycles for multi-phase faults. Challenged by such tight requirements, the Company's Transmission Protection and Controls (T-P&C) engineers have developed a 500kV breaker failure (BF) protection scheme that implements dual BF timer logics: 1) A single phase fault detector with a typical timer 2) A multi-phase (three-phase or phase-to-phase) fault detector with a shorter timer This paper presents how Progress Energy T-P&C engineers develop the dual-timer BF scheme by utilizing the associated state of the art protection system, equipment, and communication facility to meet short duration system critical clearing time while achieving operational speed, selectivity, and sensitivity. View full abstract»

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  • High-speed communication-assisted tripping and sectionalizing for distribution systems

    Publication Year: 2012 , Page(s): 129 - 136
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (363 KB) |  | HTML iconHTML  

    This paper demonstrates how to perform high speed communication-assisted tripping and sectionalizing on distribution systems. All faults are quickly cleared and the distribution system is rapidly sectionalized to restore service to the most customers possible. Inherent time delays embedded in the traditional approach are eliminated. This paper is intended for portions of rural electric distribution systems that can operate in a network. This application is limited since the majority of rural electric distribution systems consist of long tapped radial feeders; however, there are instances when a portion of a system can be operated as a looped network. The main advantage of a network is less chance of customer outages when a primary source is lost - a very important for customers with critical needs such as hospitals. View full abstract»

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  • Simplifying protection system design for distribution substations

    Publication Year: 2012 , Page(s): 137 - 151
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1832 KB) |  | HTML iconHTML  

    Orion New Zealand Limited (Orion) is a distribution utility that serves the city of Christchurch, the second largest city in New Zealand. Orion is adopting the technical capabilities found in the IEC 61850 standard and other technologies for a simple-to-implement, fit-for-purpose design for distribution protection. Orion is successfully using protective relays that provide multiple zones of protection in one device, and process bus communications, to simplify the design of their distribution protection. Careful system design allows the use of fewer protective devices, while maintaining the same level of protection system availability and reliability. Wiring and installation concerns are addressed by using process bus communications to provide remote I/O inputs for both analog measurements and digital control and status inputs, permitting the connection of only one cable to each relay. Benefits of this solution include a standard wiring design for all applications, fewer relay panels, faster installation, and simple expansion by simply connecting relays to process bus I/O units, while meeting performance requirements relating to device lifecycle, design and installation, safety, and commercial business requirements. View full abstract»

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  • Distributed generation and its impact on power grids and microgrids protection

    Publication Year: 2012 , Page(s): 152 - 161
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (363 KB) |  | HTML iconHTML  

    The National Institute of Standards and Technology, NIST, is assigned by the US Department of Energy, DoE, to drive Smart Grid developments and harmonization efforts in the power industry. Distributed Generation has been identified as one of the important areas for the Smart Grid developments. Multiple generation sources, bi-directional power flow, power flow time co-ordination and management bring significant benefits and challenges for the existing and emerging power grids and microgrids. In particular, the effect of distributed generation on protection concepts and approaches needs to be understood, and accounted for. This paper describes distributed generation concepts, applications and scenarios. Benefits and challenges are discussed and analyzed on a number of real life examples. Special considerations are provided on ensuring security and dependability, as well as on protection parameterization and coordination. View full abstract»

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  • Adaptive protection of distribution feeders

    Publication Year: 2012 , Page(s): 162 - 165
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    Adaptive protection of distribution feeders is a powerful tool for reducing the fault clearing time and improving the quality of service. The paper describes adaptive features in multifunctional Intelligent Electronic Devices (IEDs), as well as distribution protection schemes that adapt to changing substation and system conditions. View full abstract»

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  • Distance protection in distribution systems: How it assists with integrating distributed resources

    Publication Year: 2012 , Page(s): 166 - 177
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1180 KB) |  | HTML iconHTML  

    The integration of distributed generation (DG) or distributed resources in the distribution system poses technical constraints for the electrical power system owner or manager. The addition of relatively large amounts of generation to the distribution system can potentially challenge the historical settings principles and design assumptions made in developing protection and control strategies based on overcurrent protection. The necessity and complexity of additional protection and control measures increase as the aggregate DG capacity within a potential island approaches or offsets the load within that island. In addition, the varying nature of DG availability and fault current capability must also be considered. The key issues discussed and associated with DG on the distribution feeder include anti-islanding, temporary overvoltages during fault conditions, and loss of sensitivity of feeder overcurrent protection for long feeders. As the distribution system evolves to accommodate more DG, the design and implementation of the feeder protection must also evolve. This paper presents the use of distance relays for distribution protection to solve some of the DG integration problems. This paper provides real-world event report data to further demonstrate the performance of distance protection on the distribution system. A relative cost comparison between various feeder protection solutions is presented along with a discussion on options for education of distribution companies challenged with implementing distance protection for the first time. View full abstract»

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  • Optical arc flash protection: Real world experience

    Publication Year: 2012 , Page(s): 178 - 190
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (814 KB) |  | HTML iconHTML  

    Bus differential systems have long been the main method of protection systems used on 5 kV and 15 kV electrical switchgear distribution applications. However these relays have some problem areas that must be addressed for each and every application. There are several types of bus protection relays such as the multi-restraint variable, high-impedance voltage-operated and LC linear coupler types. More recently, optical arc flash protection has been used for both bus differential as well as arc flash hazard reduction. While this system also uses current transformers, many of the problems that are inherent with the bus differential system are not issues with the optical arc flash protection. This paper will outline the recent installation that utilizes an optical Arc Flash protection system (AFD) at the Yale University Medical Campus for both Bus protection as well as arc flash hazard reduction. The design and application of the optical arc flash protection as well as the logic and hardware used in the design layout are discussed. An actual arc flash bus fault resulted in a real-life arc flash event which was successfully detected by the optical arc flash system. The fault was cleared before the bus differential protection could detect a fault. This paper details the events leading up to and culminating in the arc flash event as well as the responses of the various protective relays on the system. View full abstract»

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  • Analysis of selected motor event and starting reports

    Publication Year: 2012 , Page(s): 191 - 202
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2068 KB) |  | HTML iconHTML  

    Motors are estimated to be one of the most numerous components of the electric power system. As the device that takes electrical energy and converts it to the mechanical energy needed to power processes, a motor that is unnecessarily out of service can bring an entire process to a halt, resulting in a significant loss of revenue. Conversely, the expense and time to replace a large motor damaged beyond repair mean that failing to quickly and dependably protect a motor is also a concern. Because there are many common failure modes (mechanical, electrical, thermal, and so on), root-cause analysis of a motor failure can be involved. This paper investigates several real-world events with data from both motor starting reports and event records. The data demonstrate the value of having devices capable of recording motor data during starts and fault events and of capturing and reviewing such data for the purpose of determining root cause. Lessons learned are shared to help in troubleshooting motor problems and to avoid potential misoperations in motor protection. View full abstract»

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  • Fundamentals and advancements in generator synchronizing systems

    Publication Year: 2012 , Page(s): 203 - 214
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    Synchronizing a generator to the power system must be done carefully to prevent damage to the machine and disturbances to the power system. Traditionally, power plants include a synchronizing panel to indicate what adjustments the operator should make to the governor and exciter and when it is acceptable for the operator to close the breaker. In many cases, the process is automated using an automatic synchronizer with manual control available as a backup. In power plants with more than a single generator or installations with multiple synchronizing breakers, complicated synchronizing circuits with many contacts are required to switch the voltage transformer (VT) and control signals between the operator controls and the high-voltage equipment. Maintaining proper isolation and safety grounding of sensing and control circuits often requires the use of problem-prone auxiliary relays and VTs. Today, protective-relay-grade microprocessor devices can significantly improve manual and automatic synchronizing systems. This paper discusses how this technology can simplify synchronizing circuits to reduce cost, improve reliability, and easily accomplish complete integration, automation, and remote control of the system. View full abstract»

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  • One plant, one system: Benefits of integrating process and power automation

    Publication Year: 2012 , Page(s): 215 - 250
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1453 KB) |  | HTML iconHTML  

    This paper discusses how a single integrated system architecture benefits plant operators, engineers, and managers. By taking a one plant, one system approach, end users of process and power automation systems can realize the benefits of an integrated system including increased energy efficiency, improved operator effectiveness, increased plant availability, reduced maintenance costs, and lower lifecycle costs. The architecture is based on Industrial Ethernet standards such as IEC 61850 and Profinet as well as fieldbus technologies. Emphasis is placed on connecting the substation automation system with the process control system via IEC 61850. The energy efficiency gains from integration are discussed in a power generation use case. In this use case energy efficiency is realized with integrated variable frequency drives, improved visibility into power consumption, and energy efficiency through faster plant start-up times. Substation visibility is becoming more critical in modern plants and facilities. IEC 61850 can be leveraged to provide substation visibility in a cost effective way. The substation standard as well as other open fieldbus standards can be used to create a plantwide asset management strategy. End user benefits are discussed for integrated electrical asset management. Condition based monitoring examples include Low Voltage (LV) motor starters via Profibus and Profinet while protective relays are integrated with IEC 61850. Benefits of integration help not just the process engineer but the power engineer as well. A discussion of Disturbance Recording (DR) integration is made. An integrated system allows for remote access to the DRs and automated analysis of the recordings. Faster analysis of plant disturbances means faster problem resolution and root cause analysis which equates to increased plant up-time. Several actual implementations of the one plant - one system architecture are discussed. The first case is capital expenditure (CAPEX) savings where- cost avoidance is achieved in a substation wiring project. Next, a power management success story from a major oil and gas company, Petrobras, is discussed. In this case, Petrobras utilized integrated process and power automation to lower CAPEX, operational expenditure (OPEX), and explore future energy saving opportunities. In a third case, the one plant - one system approach allows E.ON, a Swedish power company, the ability to perform remote control of hydropower plants from its dispatch center in a cost-effective way. Lastly, a success story from Boliden's Aitek open pit Copper and Zinc mine is discussed. With integrated electrical, process, and maintenance systems, Boliden is able to operate and maintain the mining site from a single control room. Parts of this paper were originally published for the Power Gen International 2010 event as “Power up your plant: An intro to integrated process and power automation”. Updates and additions have been made throughout the document. View full abstract»

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