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Development of Relays for Generator Protection

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  {\rtf1{\fonttbl{\f2 Arial Bold;}{\f3 Arial Bold;}{\f4 Arial Italic;}{\f5 Times New Roman;}{\f6 Arial;}{\f7 Arial;}{\f8 Arial;}{\f9 Arial;}{\f10 Arial Bold;}{\f11 Arial;}{\f12 Courier New;}{\f13 Arial;}{\f14 Arial Bold;}{\f15 Arial;}{\f1000000 Times New Roman;}}{\colortbl;\red0\green0\blue255;\red0\green0\blue255;\red255\green0\blue0;\red0\green0\blue255;\red0\green0\blue255;\red0\green0\blue0;\red0\green0\blue0;\red0\green0\blue0;\red0\green0\blue255;\red255\green0\blue0;\red0\green0\blue0;\red0\green0\blue0;\red0\green0\blue0;\red0\green0\blue0;}\viewkind1\viewscale100\margl0\margr0\margt0\margb0\deftab80\dntblnsbdb\expshrtn\paperw11900\paperh16840\pard\sb0\sl-240{\bkmkstart Pg1}{\bkmkend Pg1}\par\pard\ql \li3207\sb0\sl-276\slmult0 \par\pard\ql\li3207\sb0\sl-276\slmult0 \par\pard\ql\li3207\sb0\sl-276\slmult0 \par\pard\ql\li3207\sb0\sl-276\slmult0 \par\pard\ql\li3207\sb108\sl-276\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf1\f2\fs24 Development of Relays for Generator Protection \par\pard\qj \li1440\sb0\sl-230\slmult0 \par\pard\qj\li1440\sb0\sl-230\slmult0 \par\pard\qj\li1440\ri1265\sb2\sl-230\slmult0 \up0 \expndtw0\charscalex107 \ul0\nosupersub\cf3\f4\fs20 Relays are an important integral part of any power system. As generating stations are the first \up0 \expndtw0\charscalex104 element in the power system chain, the requirement of protection starts right from the generator. \up0 \expndtw-1\charscalex100 Generator is one of the costliest equipment in the powerhouse. The power stations where renovation \up0 \expndtw-1\charscalex100 and modernization (R&M) work is carried out, all the old electromechanical and static relays are being \up0 \expndtw-2\charscalex100 replaced with the smart relays. \par\pard\li8529\sb2\sl-230\slmult0\fi0\tx8889 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf4\f5\fs20 -\tab \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 mayadhar Swain\par\pard\qj \li1440\ri1254\sb180\sl-228\slmult0 \up0 \expndtw0\charscalex107 \ul0\nosupersub\cf6\f7\fs20 Relays are an important integral part of any power system. As generating stations are the first \line \up0 \expndtw0\charscalex104 element in the power system chain, the requirement of protection starts right from the generator. \line \up0 \expndtw0\charscalex104 Generator is one of the costliest equipment in the power house. Its damage causes innumerable \line \up0 \expndtw-2\charscalex100 financial loss as well as deficit of power in the system. Hence, from the very beginning of the history of \line \up0 \expndtw0\charscalex100 power generation, relays have been developed for protection of generator. The first protective relay \line \up0 \expndtw-3\charscalex100 was used in 1887. \par\pard\ql \li1440\sb191\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Development of Relays \par\pard\ql \li1440\sb110\sl-230\s  lmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf6\f7\fs20 The development of relays can be classified into four categories. These are: \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-2\charscalex100 1. First generation-Electro-mechanical relays. \par\pard\ql \li1440\sb10\sl-230\slmult0 \up0 \expndtw-1\charscalex100 2. Second generation - Static relays \par\pard\ql \li1440\sb1\sl-217\slmult0 \up0 \expndtw-1\charscalex100 3. Third generation - Programmable relays \par\pard\ql \li1440\sb13\sl-230\slmult0 \up0 \expndtw-1\charscalex100 4. Fourth generation - Smart relays. \par\pard\ql \li1440\sb190\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Electromechanical Relay \par\pard\qj \li1440\ri1261\sb112\sl-228\slmult0 \up0 \expndtw0\charscalex104 \ul0\nosupersub\cf6\f7\fs20 First generation relays are electromechanical in hardware and have been designed to perform a \up0 \expndtw0\charscalex103 single task. These relays have movable parts and hence their upkeep is a bit difficult task. These \up0 \expndtw0\charscalex100 relays also consume sufficient amount of power. Yet another limitation with these relays is that these \up0 \expndtw0\charscalex106 are not able to provide operating region of the choice of engineers. Only a best compromise is \up0 \expndtw0\charscalex104 achieved. These types of relays have become obsolete now and are no more manufactured. But \up0 \expndtw-3\charscalex100 these are found still in use in some old power stations. \par\pard\ql \li1440\sb191\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Static Relays \par\pard\qj \li1440\ri1259\sb110\sl-231\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf6\f7\fs20 These type of relays use semiconductor devices like diodes, transistors, thyristors, integrated circuits \up0 \expndtw0\charscalex100 and normal electrical components like resistor, capacitors etc. These are called static because there \up0 \expndtw-1\charscalex100 is no moving part. Due to this, its life period is more than the electromechanical relays and also these \up0 \expndtw-1\charscalex100 require less maintenance. Power consumption is less and these relays also provide fewer burdens on \up0 \expndtw0\charscalex105 CTs and PTs. But functions wise, these are similar to electromechanical relays. These are only \up0 \expndtw-1\charscalex100 functional replacement of the earlier generation relays. These relays also suffer with limitation that not \up0 \expndtw0\charscalex102 all relay characteristics can be realized. The relays are sensitive to voltage spikes or transients. At \up0 \expndtw-3\charscalex100 present these are found in use in many power stations. \par\pard\ql \li1440\sb190\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Programmable Relays \par\pard\qj \li1440\ri1251\sb110\sl-230\slmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf6\f7\fs20 Development of programmable devices provided a big leap in relay design. As a result, programmable \line \up0 \expndtw-1\charscalex100 microprocessor based relays were developed. With the presence of programmable devices, any relay \line \up0 \expndtw0\charscalex100 characteristic that can be expressed mathematically is possible to realize in the field. These are fast \line \up0 \expndtw0\charscalex104 relays require very less maintenance and consume less power. As the processor speed is more, \line \up0 \expndtw-1\charscalex100 implementation of a single protection function leaves the processor idle for significant time. This led to \line \up0 \expndtw0\charscalex100 the development of multifunction relay. As result, many generator protection functions are integrated \line \up0 \expndtw-2\charscalex100 in a single relay. So this takes less space and relay panel size is drastically reduced. \par\pard\ql \li1440\sb190\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Smart Relays \par\pard\qj \li1440\ri1255\sb110\sl-230\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf6\f7\fs20 These are the latest relays. It is known in different names like management relay, numeric relay etc. \line \up0 \expndtw0\charscalex100 The relays provide multifunctional role in power system. Apart from protection, these can be used as \line \up0 \expndtw0\charscalex100 primary of back up protection on synchronous or induction generators of 25, 50 or 60 Hz. In addition \line \up0 \expndtw0\charscalex100 to electrical protection, it also takes care of some mechanical protection like stator temperature rise, \line \up0 \expndtw-2\charscalex100 bearing temperature rise, bearing vibration etc. The various functions and features are given below. \par\pard\sect\sectd\fs24\paperw11900\paperh16840\pard\sb0\sl-240{\bkmkstart Pg2}{\bkmk  end Pg2}\par\pard\qj \li1440\sb0\sl-460\slmult0 \par\pard\qj\li1440\sb0\sl-460\slmult0 \par\pard\qj\li1440\ri5670\sb100\sl-460\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Protection: different protections in a single relay are: \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Over voltage \par\pard\ql \li1440\sb51\sl-253\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Over current \par\pard\ql \li1440\ri4027\sb16\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 100% Stator earth fault \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Reserve power \par\pard\ql \li1440\ri3632\sb0\sl-340\slmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Negative sequence over current \line \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Over flux (V/Hz) \par\pard\ql \li1440\ri4427\sb0\sl-340\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Under voltage \line \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Differential \par\pard\ql \li1440\sb82\sl-241\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Impedance protection \par\pard\ql \li1440\ri3977\sb38\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Inadvertent energization \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Over frequency \par\pard\ql \li1440\ri4310\sb0\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Under frequency \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Loss of field \par\pard\ql \li1440\ri4082\sb0\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Out-of-step protection \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Stator temperature \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Over speed \par\pard\ql \li1440\ri4217\sb0\sl-360\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Bearing vibration \line \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Control and Monitoring \par\pard\ql \li1440\ri3821\sb21\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Breaker trip coil supervision \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Breaker failure detection \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 VT fuse failure detection \par\pard\ql \li1440\ri3365\sb0\sl-340\slmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Voltage balance among three phases. \line \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Metering \par\pard\ql \li1440\ri4548\sb112\sl-350\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Current (A) \line \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Voltage (V) \line \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Power (W) \par\pard\ql \li1440\ri4099\sb0\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Reactive Power (Var) \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Energy (Wh) \par\pard\ql \li1440\ri4021\sb0\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -  \ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Reactive energy (Varh) \line \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Power factor \par\pard\ql \li1440\sb71\sl-253\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Frequency (Hz) \par\pard\ql \li1440\ri4226\sb16\sl-340\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf11\f12\fs36 -\ul0\nosupersub\cf12\f13\fs36 \ul0\nosupersub\cf6\f7\fs20 Maximum demand \line \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Event record \par\pard\qj \li1440\ri1259\sb120\sl-220\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf6\f7\fs20 These relays provide history features so that in the event of fault, the variation of different parameters \up0 \expndtw-2\charscalex100 can be studied to analyse the probable cause of the fault. \par\pard\ql \li1440\sb112\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 SCADA Compatibility \par\pard\qj \li1440\ri1255\sb139\sl-220\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf6\f7\fs20 The modern power stations are generally having SCADA system and these relays fit very well for this. \up0 \expndtw-1\charscalex100 Data can be transferred to a central master or main control system through a serial interface. \par\pard\sect\sectd\fs24\paperw11900\paperh16840\pard\sb0\sl-240{\bkmkstart Pg3}{\bkmkend Pg3}\par\pard\ql \li1440\sb0\sl-230\slmult0 \par\pard\ql\li1440\sb0\sl-230\slmult0 \par\pard\ql\li1440\sb0\sl-230\slmult0 \par\pard\ql\li1440\sb0\sl-230\slmult0 \par\pard\ql\li1440\sb0\sl-230\slmult0 \par\pard\ql\li1440\sb60\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Numeric Setting \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf6\f7\fs20 It has numeric settings with keyboard and settings are protected with password. \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Man-Machine Interface (MMI) \par\pard\qj \li1440\ri1256\sb108\sl-233\slmult0 \up0 \expndtw-2\charscalex100 \ul0\nosupersub\cf6\f7\fs20 It is best in class in man-machine interface. The settings and other parameters can be accessed using \up0 \expndtw-2\charscalex100 the integrated control and numerical keypad. Through a serial interface, the relay can be connected to \up0 \expndtw-1\charscalex100 local computer. Light-emitting diodes (LEDs) and display Screen (LCD) provide information related to \up0 \expndtw-3\charscalex100 events and functional status of the relay. \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Self Checking \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf6\f7\fs20 When any fault occurs in the relay, it gives an alarm. \par\pard\ql \li1440\sb130\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Remote Communication \par\pard\qj \li1440\ri1266\sb109\sl-232\slmult0 \up0 \expndtw-1\charscalex100 \ul0\nosupersub\cf6\f7\fs20 Some manufacturers like GE and SIEMENS have provided embedded ethernet communication \up0 \expndtw0\charscalex102 system. The relay is directly connected to Local / Wide Area Network (LAN / WAN) using TCP / IP \up0 \expndtw-1\charscalex100 protocol via a port located on the back panel of the relay. Through this, the manufacturer gets access \up0 \expndtw0\charscalex100 to relay information such as setting, oscillography, trending data and sequence of event records etc. \up0 \expndtw-1\charscalex100 the manufacturer can notice any malfunction or abnormality in the relay through Internet and also can \up0 \expndtw-2\charscalex100 rectify the same through Internet. \par\pard\ql \li1440\sb110\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf10\f11\fs20 Time Synchronisation \par\pard\qj \li1440\ri1259\sb119\sl-220\slmult0 \up0 \expndtw0\charscalex100 \ul0\nosupersub\cf6\f7\fs20 The relay has its own clock. An interface is provided for the time synchronisation of the internal clock \up0 \expndtw-2\charscalex100 via external synchronisation sources or master clock of the power station. \par\pard\ql \li1440\sb132\sl-230\slmult0 \up0 \expndtw-3\charscalex100 \ul0\nosupersub\cf2\f3\fs20 Conclusion \par\pard\qj \li1440\ri1262\sb110\sl-230\slmult0 \up0 \expndtw0\charscalex106 \ul0\nosupersub\cf6\f7\fs20 In all the new power stations, smart relays are installed due to their inherent merits. The power \up0 \expndtw0\charscalex100 stations where renovation and modernization (R&M) work is carried out, all the old elctromechanical \up0 \expndtw-3\charscalex100 and static relays are bein
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