Learn how to test a high impedance differential scheme and understand what the hirez differential scheme is supposed to do during faults. Pdf implementation of microcontroller based distance relay. Determining the coil inductance of a relay when the relay. Difference bw low and high impedance ref electricaltms.
Low impedance restricted earth fault protection is protection function to one of the protect the transformer winding with earthed neutral point. A survey of the major characteristics of these developments is. The operating characteristic of a reactance relay is shown in the figure below. Consider that the 51 relay is a lowimpedance, microprocessorbased overcurrent relay. Impendence relays observe impedance among the relays position and the.
Under impedance relay distance relay synchronising and or synchrocheck relay over or under temperature protection and control relay ac under voltage relay power directional relay under current or underpower relay bearings over temperature relay field control loss of field relay dc over voltage relay reverse phase or phase balance current relay. Impedance relay and protection rxzk 21h, 22h, assemblies. It is clear from the characteristics that if the impedance seen by the relay lies within the circle then the relay shall operate else it wont operate. The voltage drop across this impedance during fault conditions affects the voltages seen by the relay and may affect the polarizing voltage used by the distance relay. Zocholl and david costello schweitzer engineering laboratories, inc. Relays that work on the principle of impedance are know as distance relays and are used to protect transmission lines in an interconnected looped transmission grid. High impedance busbar differential protection minimum allowable ct saturation voltage calculation.
Evaluation of relaying impedance algorithms for seriescompensated line. Although directional relays have been applied successfully for. High impedance busbar differential protection will not work properly if the cts are not sized correctly for the connected circuit. Keywords digital computer applications, microprocessors. Distance relay or impedance relay working principle types. This paper presents analytical and simulation results for investigating the operation of impedance based protection relays in a power system containing a flexible alternating current transmission. Operation of impedance protection relays with the statcom. X is the reactance of the protected line between the relay location and the fault point, and r is the resistance component of the impedance. Similarly, the output of a logic function is activated, that is, high or deactivated, that is, low. These relays are implemented on a dsp tms320f2812 and their performance is evaluated which is based on operation time, dsps execution time and grading margin. We will explain the problem and offer solutions that will allow the application of distance elements.
The metrosil chosen depends on the relay setting voltage and the. The ratio of voltage v to current i gives the impedance of he line section between the relay location and the fault point. Since this type of relay operates based on the impedance of the circuit which in turn depends upon the distance of the fault from the relay location, it is called distance relay. Apr 14, 2016 the operating characteristic of impedance relay is shown below. The differential relay is one that operates when there is a difference between two or more similar electrical quantities exceeds a predetermined value.
Power quality requirements resulting from such great complex electrical network have motivated the improvement of fault location methods and development of. In some applications of high impedance relays for protection and control duties, the maximum internal fault current can develop high voltages that can damage the relay insulation. By varying commands to the analogue multiplexer the required input signals for different relaying characteristics such as impedance, reactance. Blocking of distance relays zone3 under load encroachment. Impedance based fault location experience karl zimmerman and david costello schweitzer engineering laboratories, inc. During a fault, the impedance seen by the relay does not necessarily equal the actual impedance where the fault is located.
More specifically, the relay operates depending upon the impedance between the point of fault and the point where relay is installed. Operation of based impedance protection numerical relay with statcom facts devices omar noureldeen faculty of engineering, south valley university, qena, egypt email. The relay can be on or off, that is, it has two stable states. In this paper we use the term virtual faults to refer to phenomena i.
More specifically, the relay operates depending upon the impedance between the point of fault. This paper presents a study of the impacts of the flexible ac. Microprocessor distance relays use equations to restrain or operate. Sep 01, 2018 there is one type of relay which functions depending upon the distance of fault in the line.
There is one type of relay which functions depending upon the distance of fault in the line. The relay identifiers the fault locations as expected, as the fault location is changed, the measured impedance change consequently. As an alternative, please refer to the p145 and p14nb with hid relays the mib, a member of the m ii family of economical and highly functional digital protection relays, is a microprocessor based relay that provides three phase high impedance differential protection for substation busbars of any. The research is based on quadrilateral relay from perspective impedance calculations the relay model has the ability of indicating the correct zone of operation in all cases. Twoct equivalent circuit with an external fault note that the side a and side b impedances must be equal for the overcurrent relay to measure zero current for an external fault. Data communication, micro controller, digital logiccomputer design, relay, microprocessorbased impedance relay, high voltage power lines. A communications based protection scheme where high speed. In the differential relay scheme circuit, there are two currents come from two parts of an electrical power circuit. Evaluation of relaying impedance algorithms for series. The mib has all the advantages of an electrom echanical numerical relay, with the added.
Impedance relays are use when over current relays does not offer sufficient safety. Under impedance relay distance relay synchronising and or synchrocheck relay over or under temperature protection and control relay ac under voltage relay. Three zone protection by using distance relays in simulink. The relay whose working depends on the distance between the impedance of the faulty section and the position on which relay installed is known as the impedance relay or distance relay. Three zone protection by using distance relays in simulinkmatlab. It is available in eight versions, five of these versions each with reconnecting operate values u s1 and u s2, and three versions with continuously settable operate value between 100 and 400 v. Im trying to measure the coil inductance of a relay when the relay is on and the normally open pairs of contacts are closed. A lowvoltage relay requires the use of a transformer with an open circuit secondary of between 24 and 27 volts ac. The impedance relay, type rxzk 2h, is a microprocessor based relay.
Impedance relay is protection relay which functions depending upon the distance of fault in the line. Mho relay admittance or angle admittance relay my tech info. Numerical high impedance relay with ct supervision dad n numerical high impedance relay with ct supervision description the overall differential protection uses the high impedance circulating current principle. The design incorporates two digital relaying techniques which operate in. Fundamentals and improvements for directional relays. Application guidelines for microprocessor based, high impedance bus differential relays stanley e. How does an under impedance relay work and how is it. Impedancebased fault location experience karl zimmerman and david costello schweitzer engineering laboratories, inc. Rated values rxzk 21h rated voltage ur 100 v rated current ir 1 a or 5 a scale constant is 0,1 0,2 0,4 and 1,0 x i r setting ranges. Distance relay basics free download as powerpoint presentation. We calculated that the voltage across the nonsaturated ct, when another ct saturates, is 83. The value of input and output impedance can be arranged to an appropriate value by the choice of amplifier design. Impedance calculation algorithm for microprocessor based digital protective relay neel pawar 1, saniya vichare2, shikha singh 3, vedant bhatkar4, rajeev valunjkar 5 1electrical engineering, atharva college of engineeringmumbai university, india 2electrical engineering.
We covered the basic operating principles of high impedance busbar differential protection in our previous post, i want to know how a high impedance differential scheme works. Relay logic is very important to understand the microprocessorbased relay. When a seriescompensated line suffers a fault behind its scs, as seen from the relaying point fig. Istance relays perationdepend on the agnitude of the current or ltage of the circuit. I want to know how a high impedance differential scheme works. Knowledge based approach for transmission line distance relay. Impact of high resistance faults on impedance protection perfomance. An impedance relay see figure 637 is used to provide lockout and remote reset in refrigeration, airconditioning, and other. Apr 22, 2017 impedance relay is protection relay which functions depending upon the distance of fault in the line. Published in the sel journal of reliable power, volume 1, number 1, july 2010 previously presented at the. You should read that post first before we dig deep into the calculations and considerations that explain how high impedance busbar differential schemes function.
Correct metrosil selection ensures that the best protection is obtained while maintaining a metrosil leakage current low enough to have negligible effect on the accuracy of the relay at its maximum setting voltage. The operating characteristic of impedance relay is shown below. The relay consists mainly of two input transformers, one for current and one for voltage measuring, filter circuits, microprocessor, hmi, leds for indications of relay in service, trip of directional function, trip of stage one and trip of. A very important advantage of lowimpedance ref protection is the fact that the ct ratios for the phase cts and neutral cts. It is noteworthy here that in electrical engineering, the term impedance can be applied to resistance alone or reactance alone, or a combination of the two. To enable fast operation of the impedance relay in case of lack or. I want to know how a high impedance differential scheme works we received this question from the ask chris form at. Published in the sel journal of reliable power, volume 1, number 1, july 2010 previously presented at the 2006 ieee rural electric power conference, april 2006. Manufacturing for this product has been discontinued.
The algorithms gathered in two basic families have been tested. The reach point of the relay is the point along the line impedance locus that is intersected by the boundary characteristics of the relay. Khincha department of electrical engineering indian institute of science bangalore, india 560012. Fundamentals and improvements for directional relays karl zimmerman and david costello, schweitzer engineering laboratories, inc. Study of impedance relay engineering research publication.
Microprocessor based impedance relay analog to digital. The protection consists of instantaneousdefinite time overcurrent elements 8750 and. These relays are known as distance relay or impedance relay. Mho relay admittance or angle admittance relay my tech. Khincha department of electrical engineering indian institute of science bangalore, india 560012 email. A group of the algorithms of faultloop impedance determination for digital distance relay applied for protecting a seriescompensated line has been considered. Changing the tripping decision of zone 3 from being based on the value of the measured impedance to fault to be based. Distance relay quadrilateral relay characteristics for seriescompensated transmission line p. Distance relay fundamentals 63 fault, operation does not occur because izv and v are 180 out of phase. Distance relay is the broader name of the different types of impedance relay. Abstractphase and ground directional elements are relied on for fast and secure protection throughout the power system. Protective relays, associated communication systems, voltage and current sensing devices.
Microprocessorbased distance relay request pdf researchgate. Reactance relay the current research is focused on impedance relays. Microprocessor based relays perform very well and their cost is relatively low. Microprocessorbased distance relay solutions smart grid center. The presented solution is implemented as a centralized type microprocessorbased relay with a subcycle tripping time and exceptional immunity to ct saturation. If the existing equipment is of such a nature that the same ratios are not available for both phase and neutral cts, you should use lowimpedance ref protection, because this type of protection can handle different ct ratios for phase and neutral cts. Application guidelines for microprocessorbased, high. Protection system design for substation free download as powerpoint presentation. In protective relaying terminology, however, an impedance relay has a characteristic that is different from that of a relay responding to any component of impedance and therefore, the. Impedance relay and protection rxzk 21h, 22h, assemblies 23h. Observe that for the balance point fault, the v is exactly equal to iz. Impedance calculation algorithm for microprocessor based. High impedance principle means that protective relay has a.
Follow this link to ask your own question and it might appear in a future blog post. This paper presents analytical and simulation results for investigating the operation of impedancebased protection relays in a power system containing a flexible alternating current transmission. In operating characteristics of an impedance of the circuit is compared with voltage at relay location. The authors describe the design and implementation of a novel microprocessor based relay for transmission line protection.
Abstractthe protection of transmission lines is traditionally. Locus of the power swing, occurring on the long transmission lines during wrong synchronization etc. Microprocessor based impedance relay free download as word doc. The metrosil chosen depends on the relay setting voltage and the maximum secondary internal fault current. To overcome the problem of spill current due to ct221 22 is. A suggested method to calculate the source impedance for the purpose of classifying line length is to place a short circuit at the remote bus boundary of the line zone and calculate the source impedance as the voltage drop from the source to the relay location divided by the fault current. Microprocessor base protection of 2kv line using impedance. Impedance relay and protection assemblies rxzk 21h, 22h, 23h and razk 1mrk 509 006ben page 3 technical data table 1. Application guidelines for microprocessorbased, highimpedance bus differential relays stanley e. Impedance relay and protection assemblies rxzk 21h, 22h, 23h and razk 1mrk 509 006ben page 5 rxzk 22h rated voltage ur 100 v rated current ir 1 a or 5 a scale constant is 0,1 0,2 0,4 and 1,0 x i r. A typical wiring diagram for a lowvoltage impedance relay is shown in figure 638. It is an electromagnetic induction cup type mho relay. High impedance differential relay radha 1mrk 509 015ben page 2 design the radha relay is part of the combiflex family.
Knowledge based approach for transmission line distance. This paper present a microprocessorbased distancerelaying scheme suitable for the protection of ehv lines. The relay compares secondary values of v and i, as to measure their ratio which is an impedance z m. A simple form of mho relay admittance or angle admittance relay shown in the figure below. The relay will attempt to look at the ratio of voltage to current to. High impedance busbar differential protection valence.
A second significant difference is that the operating current of the lowimpedance ref protection is not realized by ct connection. For the impedance z as shown in figure, the current is lagging behind the voltage by angle o. A range of metrosil varistors, primarily based on 150mm diameter discs, has been developed to limit this voltage to a safe level. The purpose of this study is to investigate low impedance restricted earth fault algorithm in numerical relays. Determining the coil inductance of a relay when the relay is. Introduction microprocessorbased relays have made the installation.
The relay has a rated ac voltage of 110v and a rated current of 21ma. High impedance differential protection in the mib relay foreword ge multilins mib differential protection relay is a digital, microprocessor based relay equivalent in function to ge multilins pvd high speed, electromechanical differential relay. More complex methods of controlling impedance in multistage amplifiers, using negative feedback, is dicussed in amplifiers module 3. Knowledge based approach for transmission line distance relay coordination ravikumar b. This is because the relay measures the apparent impedance based on the voltage drop experienced at the relay location and the fault and the measured current at the. Published in sel journal of reliable power, volume 2, number 3, september 2011 previously presented at the 36th annual western protective relay conference, october 2009. This is true for the threephase fault shown also for a phasetophase fault and for a phase distance function only. A new algorithm for digital lowimpedance protection of. Operating characteristic of impedance relay the operating characteristic of impedance relay in terms of voltage and current is shown in fig. Introduction microprocessor based relays have made the installation. Performance analysis of power swing in distance relay. With lowimpedance ref, the relay measures all four cts necessary to realize the element.
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