Aug 31, 2018 protection of lines or feeder august 31, 2018 february 24, 2012 by electrical4u as the length of electrical power transmission line is generally long enough and it runs through open atmosphere, the probability of occurring fault in electrical power transmission line is much higher than that of electrical power transformers and alternators. But it is desired that fault in any feeder or transformer connected to the busbar should not disturb busbar system. Introduction transmission lines are a vital part of the electrical distribution system, as they provide the path to transfer power between generation and load. Transmission line protection based on travelling waves. One set of electromechanical relays or another pilot relaying scheme with microwave as communication channel are used as backup protection system. It is a radial transmission line and its length is about 180km with a load of about 30mva, including the gazaoua load in niger republic. Outline transmission line introduction what is distance protection.
Zone 3 is the backup protection for all the lines connected to the remote end bus. Best practices for protection and control applications for. Outline of discussion protection and control basics protection fundamentals transmission line protection robust protective relaying scheme design substation configuration power system nerc requirements realworld examples. The protection scheme used on the 2kv transmission line is the nonpilot threezone distance. Current differential line protection current differential relaying is a method of extending the benefits of differential protection as applied to transformers, buses or generators to the protection of transmission lines. Single line toground, line to line and double line toground faults are unbalanced in nature. The time of operation of such protection is a function of the ratio of voltage and current, i. As applied to line protection, the differential principle faced the limitations of line length. Series compensated transmission line protection using. Ge multilin application advantages before considering using a ge multilin relay for a specific transmission line protection application, it is important to understand how the relay meets some more general application requirements for simplicity, security, and dependability.
Zone 2 is used to cover the rest of the protected line and provide some backup for the remote end bus. Adaptive current differential protection schemes for. Pullman, wa, usa abstractthis paper describes a protective relay for fast and reliable transmission line protection that combines elements. These techniques use voltage and current signals at both ends and thus require a complicated communication channel, which affects the reliability and cost of the protection schemes. The overreaching transfer trip scheme provides highly secure transmission line protection since a trip signal is required from both ends of the line for tripping to occur. Introduction it is necessary for the for electrical engineering graduates who takes switchgear and protection subject understanding the protection schemes are very important. Dec 26, 2015 protection of transmission lines distance protection by, rohini haridas assistant professor, dept of electrical engineering, ssgm college of engineering,shegaon 2. Three zone protection by using distance relays in simulinkmatlab. Power transmission line protection systems is one of the most important system under electrical power system.
The objective of a protection scheme is to keep the power system stable by isolating only the components that are under. Three zone protection by using distance relays in simulink. Transmission lines operate at voltage levels from 69kv to 765kv, and are ideally tightly interconnected for reliable operation. Source1 is simulated with different source to line impedance ratios sir while keeping the source1 impedances constant at sir1. The dependability of the scheme may be less than the blocking schemes since the trip signal has to be received before the tripping is initiated. According to the north american electric reliability corporation nerc misoperations report, approximately. The implementation of distance relays requires understanding of its operating principles. Powersystem protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults through the disconnection of faulted parts from the rest of the electrical network. Pilot schemes for transmission line protection eep. Transmission line protection system for increasing power system requirements armando guzman, joe mooney, gabriel benmouyal, normann fischer, and bogdan kasztenny schweitzer engineering laboratories, inc. Comparing current flowing into a line to the current flowing out of the same line allows for a simple protection scheme. Instant isolation of fault is necessary to maintain the system stability.
Abb switzerland ltd numerical line protection power technology systems rel3164 1mrk5060ben page 4 application the fully numerical protection terminal rel3164 is a compact line terminal. Overcurrent protection is the simplest and most economical of tl protection schemes. Unlike traditional protection schemes, this technique offers a new concept in network protection. An improved fault detection classification and location.
The protection scheme used on the 2kv transmission line is. The physical construction of the transmission line is also a factor in protection system application. Protection of transmission line using gps authorstream. New differential protection scheme for tapped transmission line. Security is harder to obtain, but can be improved through the use of high quality equipment, selfchecking relays, and avoiding overly complicated protection schemes. Describe current and voltage transformers and their impact on transmission line protection scheme performance. The working principle of merz price balance system is quite simple. Carrier current protection of transmission lines methods. Outline of discussion protection and control basics protection fundamentals transmission line protection robust protective relaying scheme design substation configuration. Proposed work has made an attempt to find solution to the problem of fault detection and location by relay using post fault high frequency signals. The balanced faults in a transmission line are three phase shunt and three phases to ground circuits. Transmission lines a vital part of the power system.
This is because power systems generally tolerate the loss of additional elements better than uncleared faults. Distance protection relay is widely spread employed for the protection of highvoltage ac transmission line and distribution lines. Abstractline current differential protection creates challenges for relay design and application. The objective of a protection scheme is to keep the power system stable by isolating only the components that are under fault, whilst leaving as much of the network as. Several differential schemes are applied for protection of line but mess price voltage balance system and translay scheme are most popularly used. This problem is caused by the interaction between the phase lines of the two circuits, due to their mutual coupling. Like lnost conventional distance protective schemes known to date, the following approach will be based o11 tire exist. This webinar brought to you by the relion product family. Protection of complex transmission lines parallel feeders. New differential protection scheme for tapped transmission. Modern line current differential protection solutions.
In this scheme of line protection, identical ct is connected to each of the both ends of the line. Security is challenged every time faults occur in adjacent zones of protection, but dependability is only challenged when the fault is inzone. Transmission system is a system which between the generation and the distribution centers. In these protection schemes some electrical quantities such as the phase angle of current, direction of power flow etc.
Transmission line protection principles ge grid solutions. Recent techniques used in transmission line protection. Transmission line models for line protection m vitins brown boveri research centre, ch5405 baden, switzerland methods for the protection of power transmission lines can be based on various line models ranging from a 50 hz impedance, an lr series circuit, and. Nonpilot overcurrent protection of transmission lines. Key words switch gear protection, distance relay, line protection, matlabsimulink, impedance. Transmission and distribution lines protection transmission lines are exposed to short circuits between phases or from phase to ground. Electrical power transmission line protection systems. Transmission lines can vary in length from several hundred feet to several hundred miles, and in voltage linetoline from 46kv.
Realworld examples because power systems are really only tested when fault occurs, some systems. It provides faster protection as compared to overcurrent relay. Current differential line protection setting consideration. This impedance between the relay and the fault depends on the electrical distance between them. It is designed to provide highspeed selective protection in distribution, mv and hv transmission systems. To overcome various problems that associated with parallel line protection, a variety of modern day improvements are available such as improved distance protection schemes, unit type protection, distance protection accuracy and backup protection. A directional comparison scheme using the average of superimposed components s. They have replaced the overcurrent protection because of the following reasons. There are two main power transmission system which use in electrical industry. Pdf this paper describes an advanced protective relay system for highspeed transmission line protection.
Construction can be simple, such as a single wood pole with insulators atop a crossarm, with little spacing between the conductors and from the conductors to ground. Select the appropriate transmission line protection schemes for various applications. Time domain complete protection scheme for parallel. Distance protection relay is the name given to the protection, whose action depends on the distance of the feeding point to the fault. Single linetoground, linetoline and double linetoground faults are unbalanced in nature. The application of such line models for deriving distance protection schemes is discussed. Standard transmission line protection methods may include phase overcurrent, ground. A trip signal will be sent by the relay to a circuit breaker with the purpose of disconnecting. Pilot relaying protection is a form of unit protection used for the protection of transmission line sections. Transmission line protection system for increasing power. There are several methods available for the protection of transmission and distribution lines 69.
Identify, apply, and calculate settings for transmission line protection schemes, including directional overcurrent, distance, and pilot protection. Nov 08, 2014 pilot relaying protection is a form of unit protection used for the protection of transmission line sections. They must be prepared with sufficient knowledge and understands before. Transmission line setting calculations beyond the cookbook. Gandhi institute of industrial technology presented by sumit kumar padhy, regdno1006027 logo btech seminar presentation references zhiqian q bo weller, tom lomas and miles a, redfern positional protection of transmission system. The transmission line is simulated using a frequency dependent transmission line model. Communicationbased protection rationale zdistance protection can clear faults instantaneously for 60% to 80% of the line length zprotection speed may be critical to maintain system stability zhighspeed autoreclosing application. What is difference between busbar protection and line. Zone 3 also provides backup protection for adjacent lines sections.
In 8,9 ann based schemes have been developed, but these ann based relays are not directional and also they do not estimate the fault location. This chapter presents two examples of the mmbased method used for protection of transmission lines. Line faults due to lightning, storms, vegetation fall, fog and salt spray on dirty insulators are beyond the control of man. Request pdf adaptive current differential protection schemes for transmissionline protection throughout the history of power system protection, researchers have strived to increase. This paper describes different cases of parallel transmission lines and analyzes some well known application problems associated with their protection. Best practices for protection and control applications for transmission substations. Carrier current protection of transmission lines carrier current protection scheme is mainly used for the protection of the long transmission line. Mix of communication system like power line carrier plc or microwave are used for communication redundancy. In the carrier, current protection schemes, the phase angle of the current at the two phases of the line are compared instead of the actual current. Contemporary power systems are associated with serious issues of faults on high voltage transmission lines. As the length of electrical transmission line is generally long enough and it runs through open atmosphere, the probability of occurring fault in electrical power transmission line. The range of the possible fault current, the effect of load, the question of directionality and the impact of system configuration are all part of the transmission line protection problem.
Line distance measurement methods and characteristics apparent impedance of fault loops and differences in phase and ground measurements the importance of faulted phase selection step distance line protection zone acceleration schemes nonpilot basics of communications assisted schemes optional time permitting. As the length of electrical power transmission line is generally long enough and it runs through open atmosphere, the probability of occurring fault in electrical power transmission line is much higher than that of electrical power transformers and alternators. Transmission line protection using travelling waves generated at the time of fault are. Transmission line models for line protection sciencedirect. An overview of transmission line protection by artificial. That is why a transmission line requires much more protective schemes than a transformer and an alternator. Protection of transmission lines distance protection by, rohini haridas assistant professor, dept of electrical engineering, ssgm college of engineering,shegaon 2. In adra, a morphological fault detector mfd designed based on mm is used to determine the occurrence of a fault. Home download center electrical engineering books and technical guides relay control and protection guides transmission line protection principles factors influencing line protection the protection system selected should provide redundancy to limit the impact of device failure, and backup protection to ensure dependability. Busbar protection in early days only conventional over current relays were used for busbar protection. Pdf advanced transmission line protection system researchgate. Wavelet transform based schemes have been proposed in 1012 for fault classi. Nonpilot and pilot schemes redundancy considerations security for dualbreaker terminals outofstep relaying singlepole tripping seriescompensated lines 2 ge october 3, 2015. A substation can employ many relaying systems to protect the equipment associated with the station.
Methods for the protection of power transmission lines can be based on various line models ranging from a 50 hz impedance, an lr series circuit, and a. Protective relay utilizes current and voltage signals to detect, classify, and locate the fault in transmission line. Protection schemes are designed around the differing. Transmission line protection transmission lines can vary in length from several hundred feet to several hundred miles, and in voltage line to line from 46kv to 750kv. Transmission line protection free download as powerpoint presentation.