电气系统的保护(外文文献翻译)

Circuit breaker断路器Compressed air circuit breaker is a mechanical switch equipment, can be i 空气压缩断路器是一种机械开关设备，能够在n normal and special conditions breaking current (such as short circuit cur 正常和特殊情况下开断电流（比如说短路电流）。

rent). For example, air circuit breaker, oil circuit breaker, interference circ 例如空气断路器、油断路器，干扰电路的导体uit conductor for the application of the safety and reliability of the circuit 干扰电路的导体因该安全可靠的应用于其中，breaker, current in arc from is usually divided into the following grades: a 电流断路器按灭弧远离通常被分为如下等级：ir switch circuit breaker, oil circuit breaker, less oil circuit breaker, compr 空气开关断路器、油断路器、少油断路器、压缩空essed air circuit breaker, a degaussing of isolating switch, six sulfur hexaf 气断路器、具有消磁性质的隔离开关、六氟luoride circuit breaker and vacuum breaker. Their parameters of voltage, 化硫断路器和真空断路器。

他们的参数有电压等级、current, insulation level of breaking capacity, instantaneous voltage off ti 开断容量的电流、绝缘等级开断时间的瞬时电压恢复和me of recovery and a bombing. Breaker plate usually include: 1 the maxi 轰炸时间。

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p m ic ro co mp ut er i s t he c ul mi na ti on of both t h e de ve lo pm en t of the dig it al com pu te r an d th e in te gr at ed c i rc ui t arg ua bl y t h e tow m os t s ig ni f ic an t i nv en ti on s o f t he 20th c e nt ur y [1].Th es e tow type s of arch it ec tu re are foun d in sin g le -ch i p m i cr oc om pu te r. Som e empl oy the spli t prog ra m/da ta me mo ry of the H a rv ar d ar ch it ect u re , sh ow n in Fig.3-5A -1, oth ers fo ll ow the p h il os op hy , wi del y ada pt ed for gen er al -p ur po se com pu te rs and m i cr op ro ce ss o r s, o f ma ki ng no log i ca l di st in ct ion be tw ee n p r og ra m and dat a me mo ry as in the Pr in ce to n arch ite c tu re , show n i n Fig.3-5A-2.In gen er al ter ms a sin gl e -chi p mic ro co mp ut er i sc h ar ac te ri zed b y t he i nc or po ra ti on of a ll t he un it s of a co mp uter i n to a sin gl e d ev i ce , as sho wn inFi g3-5A -3.Fig.3-5A-1 A Harvard typeFig.3-5A-2. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM.R OM is usua ll y for the pe rm an ent,n o n-vo la ti le stor a ge of an app lic a ti on s pr og ra m .M an ym i cr oc om pu te rs and m are inte nd e d for high -v ol um e ap pl ic at ions a n d he nc e t h e eco n om ic al man uf act u re of th e de vic e s re qu ir es t h at t he cont en t s o f t he prog ra m me m or y be co mm it t ed perm a ne ntly d u ri ng the man ufa c tu re of ch ip s .Cl ea rl y, thi s im pl ie s a r i go ro us app ro ach to ROM cod e deve l op me nt sin ce cha ng es can not b e mad e afte r manu f a c tu re .Th is dev e lo pm en t proc ess may invo lv e e m ul at io n us in g aso ph is ti ca te d de ve lo pm en t sy ste m wit h a h a rd wa re emu la tio n cap ab il it y as w el l as the use o f po we rf ul s o ft wa re too ls.So me man uf act u re rs pro vi de add it io na l RO M opt i on s by i n cl ud in g in their ra n ge dev ic es wit h (or int en de d fo r use wit h u s er pro gr am ma ble me mo ry. Th e sim p le st of th es e is usu al ly d e vi ce whi ch can op er at e in a micro p ro ce ssor mod e by usi ng som e o f the inp ut /outp u t li ne s as an ad dr es s an d da ta b us fora c ce ss in g ex te rna l mem or y. Thi s t y pe of de vi ce can beh av ef u nc ti on al ly as th e sing le chip mi cr oc om pu te r from whi ch it is d e ri ve d al be it wit h re st ri ct ed I/O and a mod if ied ex te rn al c i rc ui t. The use of thes e d ev ic es is com mo n eve n in prod uc ti on c i rc ui ts wher e t he vo lu me does no tj us ti f y t h e d ev el o pm en t c osts o f c us to m o n -ch i p R OM [2];t he re c a n s ti ll bea s ignif i ca nt saving i n I /O and o th er c h ip s com pa re d to a conv en ti on al mi c ro pr oc es sor b a se d ci rc ui t. Mor e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be o b ta in ed in th e fo rm of va ri an ts w it h 'p ig gy -b ack 'E P RO M(Er as ab le pro gr am ma bl e ROM s oc ke ts or dev ic e s with EPROM i n st ea d o f RO M 。

外文出处：Farhadi, A. (2008). Modeling, simulation, and reduction of conducted electromagnetic interference due to a pwm buck type switching power supply. Harmonics and Quality of Power, 2008. ICHQP 2008. 13th International Conference on, 1 - 6.Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply IA. FarhadiAbstract:Undesired generation of radiated or conducted energy in electrical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters especially in switching power supplies improves efficiency but leads to EMI. Different kind of conducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power electronic systems producers must regard EMC. Modeling and simulation is the first step of EMC evaluation. EMI simulation results due to a PWM Buck type switching power supply are presented in this paper. To improve EMC, some techniques are introduced and their effectiveness proved by simulation.Index Terms:Conducted, EMC, EMI, LISN, Switching SupplyI. INTRODUCTIONFAST semiconductors make it possible to have high speed and high frequency switching in power electronics []1. High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency interference appeared []2. Compliance with electromagnetic compatibility (EMC) regulations is necessary for producers to present their products to the markets. It is important to take EMC aspects already in design phase []3. Modeling and simulation is the most effective tool to analyze EMC consideration before developing the products. A lot of the previous studies concerned the low frequency analysis of power electronics components []4[]5. Different types of power electronics converters are capable to be considered as source of EMI. They could propagate the EMI in both radiated and conducted forms. Line Impedance Stabilization Network (LISN) is required for measurement and calculation of conducted interference level []6. Interference spectrum at the output of LISN is introduced as the EMC evaluation criterion []7[]8. National or international regulations are the references forthe evaluation of equipment in point of view of EMC []7[]8.II. SOURCE, PATH AND VICTIM OF EMIUndesired voltage or current is called interference and their cause is called interference source. In this paper a high-speed switching power supply is the source of interference.Interference propagated by radiation in area around of an interference source or by conduction through common cabling or wiring connections. In this study conducted emission is considered only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of elements, source lines and cabling provide paths for conducted noise or interference. Electromagnetic conducted interference has two components as differential mode and common mode []9.A. Differential mode conducted interferenceThis mode is related to the noise that is imposed between different lines of a test circuit by a noise source. Related current path is shown in Fig. 1 []9. The interference source, path impedances, differential mode current and load impedance are also shown in Fig. 1.B. Common mode conducted interferenceCommon mode noise or interference could appear and impose between the lines, cables or connections and common ground. Any leakage current between load and common ground couldbe modeled by interference voltage source.Fig. 2 demonstrates the common mode interference source, common mode currents Iandcm1 and the related current paths[]9.The power electronics converters perform as noise source Icm2between lines of the supply network. In this study differential mode of conducted interference is particularly important and discussion will be continued considering this mode only.III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS Application of electrical equipment especially static power electronic converters in different equipment is increasing more and more. As mentioned before, power electronics converters are considered as an important source of electromagnetic interference and have corrupting effects on the electric networks []2. High level of pollution resulting from various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers are so sensitive to power system disturbances including voltage and frequency variations. The best solution to reduce corruption and improve power quality is complying national or international EMC regulations. CISPR, IEC, FCC and VDE are among the most famous organizations from Europe, USA and Germany who are responsible for determining and publishing the most important EMC regulations. IEC and VDE requirement and limitations on conducted emission are shown in Fig. 3 and Fig. 4 []7[]9.For different groups of consumers different classes of regulations could be complied. Class Afor common consumers and class B with more hard limitations for special consumers are separated in Fig. 3 and Fig. 4. Frequency range of limitation is different for IEC and VDE that are 150 kHz up to 30 MHz and 10 kHz up to 30 MHz respectively. Compliance of regulations is evaluated by comparison of measured or calculated conducted interference level in the mentioned frequency range with the stated requirements in regulations. In united European community compliance of regulation is mandatory and products must have certified label to show covering of requirements []8.IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENTA. Line Impedance Stabilization Network (LISN)1-Providing a low impedance path to transfer power from source to power electronics converter and load.2-Providing a low impedance path from interference source, here power electronics converter, to measurement port.Variation of LISN impedance versus frequency with the mentioned topology is presented inFig. 7. LISN has stabilized impedance in the range of conducted EMI measurement []7.Variation of level of signal at the output of LISN versus frequency is the spectrum of interference. The electromagnetic compatibility of a system can be evaluated by comparison of its interference spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 kHz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations. In practical situations, the LISN output is connected to a spectrum analyzer and interference measurement is carried out. But for modeling and simulation purposes, the LISN output spectrum is calculated using appropriate software.基于压降型PWM开关电源的建模、仿真和减少传导性电磁干扰摘要：电子设备之中杂乱的辐射或者能量叫做电磁干扰(EMI)。

Power System ProtectionsThe steady-state operation of a power system is frequently disturbed by various faults on electrical equipment. To maintain the proper operation of the power system, an effective, efficient and reliable protection scheme is required. Power system components are designed to operate under normal operating conditions. However, if due to any reason, say a fault, there is an abnormality, it is necessary that there should be a device which senses these abnormal conditions and if so, the element or component where such an abnormality has taken place is removed, i.e. deleted from the rest of the system as soon as possible. This is necessary because the power system component can never be designed to withstand the worst possible conditions due to the fact that this will make the whole system highly uneconomical. And therefore, if such an abnormality takes place in any element or component of the power system network, it is desirable that the affected element / component is removed from the rest of the system reliably and quickly in order to restore power in the remaining system under the normal condition as soon as possible.A power system represents a very large capital investment. To maximize the return on this outlay. the system must be loaded as much as possible. For this reason it is necessary not only to provide a supply of energy which is attractive to prospective users by operating the system ,but also to keep the system in full operation as far as possible continuously, so that it may give the best service to the consumer, and earn the most revenue for the supply authority. Absolute freedom from failure of the plant and system network cannot be Guarani- teed. The risk of a fault occurring, however slight for each item, is multiplied by the number of such items which are closely associated in an extensive system, as any fault produces repercussions throughout the network. When the system is large, the chance of a fault occurring and the disturbance that a fault would bring are bothso great that with ou equipment to remove faults the system will become, in practical terms, inoperable. The object of the system will be defeated if adequate provision for fault clearance is not made. Nor is the installation of switch gear alone sufficient; discriminant protective gear, designed according to the characteristics and requirements of the power system. must be provided to control the switch gear. A system is not properly designed and managed if it is not adequately protected.The protection scheme includes both the protective relays and switching circuits, i.e. circuit breakers. The protective relay which functions as a brain is a very important component. The protective relay is a sensing device, which senses the fault, determines its location and then send command to the proper circuit breaker by closing its trip coil. The circuit breaker after getting command from the protective relay, disconnects only the faulted element. This is why the protective relay must be reliable, maintainable and fast in operation.In early days, there used to be electromagnet relay of induction disk-type. However, very soon the disk was replaced by inverted cup, i.e. hollow cylinder and the new relay obtained was known as an induction cup or induction cylinder relay. This relay, which is still in use, possesses several important features such as higher speed, higher torque for a given power input and more uniform torque.However, with the advent of electronic tubes, electronic relays having distinct features were developed during 1940s. With the discovery of solid state components during 1950s, static relays with numerous advantages were developed. The use of digital computers for protective relaying purposes has been engaging the attention of research and practicing engaging the attention of research and practicing engineers since late 1960s and 1980s. Now, the microprocessor/mini computer-basedrelaying scheme, because of its numerous advantages such as self-checking feature and flexibility, has been widely used in power systems all over the world.The overall system protection is divided into following sections:(i) Generator protection,(ii) Transformer protection,(iii) Bus protection,(iv) Feeder protection,(v) Transmission line protection.Basic Requirements to Protective RelaysAny protection scheme, which is required to safeguard the power system components against abnormal conditions such as faults, consists basically of two elements: (i) Protective relay and (ii) Circuit breaker. The protective relay which is primarily the brain behind the whole scheme plays a very important role. Therefore proper care should be taken in selecting an appropriate protective relay which is reliable, efficient and fast in operation. The protective relay must satisfy the following requirements:(1) Since faults on a well designed and healthy system are normally rare, the relays are called upon to operate only occasionally. This means that the relaying scheme is normally idle and must operate whenever fault occurs. In other words, it must be reliable.(2) Since the reliability partly depends upon the maintenance, the relay must be easily maintainable.(3) The alliteration of the relay can be in two ways. One is the failure to operate in case a fault occurs and second is the relay operation when there is no fault. As a matter of fact, relay must operate if there isa fault and must not operate if there is no fault.(4) Relaying scheme must be sensitive enough to distinguish betweennormal and the faulty system.Protective RelaysThe function of the protective relays is to sense the fault and energize the trip coil of the circuit breaker. The following types of protective relays are used for the apparatus such as synchronous machines, bus bar, transformer and the other apparatus and transmission line protection.(1)Crosscurrent relays.(2)Under voltage relays.(3)Infrequence relays.(4)Directional relays.(5)Thermal relays.(6)Phase sequence relays such as (i) negative sequence relays and, (ii) zero sequence relays.(7)Differential relays and percentage differential relays.(8)Distance relays such as (i) plane impedance relays, (ii) angle impedance relays, i.e. Ohm or reactance relays, (iii) angle admittance relays, i.e. Ho relays and, (iv) offset and restricted relays.(9)Pilot relays such as (i) wire pilot relays, (ii) carrier channel pilot relays, (iii) microwave pilot relays.There are different types of the relaying scheme based on construction. They are: (i) electromagnet type, (ii) thermal relays, (iii) transactor relays, (iv) rectifier bridge relay, (v) electronic relays, (vi) static relays, (vii) digital relaying schemes.Faults and Their Damages on Power SystemsFaults on Transmission LinesBecause transmission lines are exposed to lightning and otheratmospheric hazards, faults on them occur more frequently than those in apparatus. The types of faults taking place on a transmission line are listed, in the order of severity, as following:(1)3-φ fault (LLL fault) or 3-φ to ground fault (LLLG fault) with or without fault impedance. This fault which is most severe but least common is only one in number.(2)Double line to ground (LLG) fault with or without fault impedance. This fault is less severe but more common than 3-φ fault. However, this type of faults are three in number.(3)Line to line (LL) fault. This fault is more common but less severe than the above faults. These faults are also three in number.(4)Single line to ground (LG) fault. This fault is the least severe but the most common one. These faults are also three in number.From the above, we conclude that are four types of faults which are ten in number. The first three faults such as LLL or LLLG, LLG and LL faults involving two or more phases are known as phase fault while the fourth fault, namely, LG fault, is called ground fault. All of the line faults will bring the system into abnormal operating conditions, and may damage electrical equipment. Therefore, the faulty lines must be isolated from the system by protection relays.Faults in Synchronous MachinesGenerators are subjected to varieties of possible hazards when they are in operation. The possible hazards or faults which may occur in a synchronous generator can broadly be classified into two categories: (i) internal faults within the generator, (ii) abnormal operating and/or abnormal system conditions caused by external faults. Internal faults of a generator mainly include gustatory faults and rotor faults.Gustatory Faults----Within the gustatory winding, faults can occurdue to failure of insulation (i.e. dielectric) and open circuit of conductor. Failure of insulation can lead to the short circuit between: (i) two or more phases, (ii) phase and core, (iii) two or more turns of the same phase (i.e. inter turn fault).Failure of insulation can occur due to over voltage, overheating caused by unbalanced loading, by overloading, by ventilation troubles, and by improper cooling of lubrication oil. It may also be caused by conductor movement due to forces exerted by short circuit currents or out of step operation. The most common fault in the gustatory winding is ground fault; about 85% of the faults are phase to ground faults in any generator winding. Phase to ground fault if persists may lead to phase to phase fault and even to phase-phase-phase fault (three-phase short circuit), which is the most severe fault though least common. The cause of over voltage which ultimately results into failure of insulation can be due to over speed of the prime mover, or due to defective voltage regulator; however, these days governors and voltage regulators act very fast and prevent any damage to the winding insulation.Rotor Faults----In the rotor winding also failure of insulation between field winding and core or two or more turns can occur. These faults may ultimately result in unbalanced currents and heating of the rotor. If the rotor is foregrounded, first earth fault does not show any effect but a second earth fault increases the current in the affected portion of winding which may cause distortion and permanent damage. It is advisable to open the field circuit breaker even with single earth fault to avoid second earth fault to avoid second earth fault so as to prevent local heating.Abnormal operating conditions / miscellaneous faults----There are a number of abnormal conditions which do not occur in the gustatory or rotor winding, but are undesirable since they can damage the generator. Eachof these conditions is discussed in the following.(1)Loss of synchronic. This condition can occur either due to loss of field excitation or governor becomes defective. During out of step condition, as the swing angle between the generated voltage of the machine and that of other units in the system changes, the current in any such unit varies in magnitude. The current surges that result are cyclical in nature, their frequency being a function of reactive rate of slip of the poles in the machine. The resulted high peak currents and off-frequency operation can cause winding stresses, and pulsating torques which can excite mechanical resonances that can be potentially damaging to the generator and to the shifts. Thus generator should be tripped without any delay within the first slip cycle to avoid any major damage.(2)Over speed. The cause of over speed is sudden loss of a very large load; sometimes this happens due to tripping of circuit breaker near the generator end. In the case of steam turbine, the steam can be shut off immediately but in case of hydro turbine, the water flow cannot be stopped quickly, due to the mechanical and hydraulic inertia. The governor controls the over speeding so as to avoid any high voltage, high frequency and manically damage to the generators. The setting of an over speed rating may be 115% for steam turbines and 140% for hydro-disturbing.(3)Motoring. In a mufti-generator system, when prime mover fails to provide required speed, the generator may act as a motor, drawing power from the system, instead of supplying power. Generally motoring is prevented by sensitive reverse power relay which operates on about 0.5% reverse power.(4)Under speed. Due to failure of steam or water supply to the prime mover, the speed of the generator will reduce and if the reverse power relay fails, then under speed and/or infrequence relay comes into picture and trips the circuit breaker.(5)Loss of excitation. Excitation failure may be caused by a faulty field circuit breaker or failure of the exciter. It can be detected by an undercurrent dc relay. Due to failure of excitation, the synchronous generator may act as an induction generator thereby absorbing reactive power (i.e. sink of reactive power). Turbine generator tends to overheat the rotor and the slot wedges under these conditions because of heavy currents in these parts and sometimes arcing occurs at metal wedges in the slots.(6)Over voltage. This may be caused due to over speed or elicitation when speed governor or voltage regulator fails to act as desired.(7)Gustatory overheating. Overheating may occur due to bearing failure, overloading, inadequate lubrication, or improper cooling of lubricating oil, etc. Overheating affects the dielectric strength of insulation.(8)External faults. Whenever abnormal conditions occur beyond the generator protection zone, the generator is also affected since the very source of power to the external fault is the generator itself. These conditions can be detected by the magnitude of negative sequence current, second harmonic current in field current and line crosscurrent relay.Power System ProtectionsIntroductionThe steady-state operation of a power system is frequently disturbed by various faults on electrical equipment. To maintain the proper operation of the power system, an effective, efficient and reliable protection scheme is required. Power system components are designed to operate under normal operating conditions. However, if due to any reason, say a fault, there is an abnormality, it is necessary that there should be a device which senses these abnormal conditions and if so, the element or component where such an abnormality has taken place is removed, i.e.deleted from the rest of the system as soon as possible. This is necessary because the power system component can never be designed to withstand the worst possible conditions due to the fact that this will make the whole system highly uneconomical. And therefore, if such an abnormality takes place in any element or component of the power system network, it is desirable that the affected element / component is removed from the rest of the system reliably and quickly in order to restore power in the remaining system under the normal condition as soon as possible.The protection scheme includes both the protective relays and switching circuits, i.e. circuit breakers. The protective relay which functions as a brain is a very important component. The protective relay is a sensing device, which senses the fault, determines its location and then send command to the proper circuit breaker by closing its trip coil. The circuit breaker after getting command from the protective relay, disconnects only the faulted element. This is why the protective relay must be reliable, maintainable and fast in operation.In early days, there used to be electromagnet relay of induction disk-type. However, very soon the disk was replaced by inverted cup, i.e. hollow cylinder and the new relay obtained was known as an induction cup or induction cylinder relay. This relay, which is still in use, possesses several important features such as higher speed, higher torque for a given power input and more uniform torque.However, with the advent of electronic tubes, electronic relays having distinct features were developed during 1940s. With the discovery of solid state components during 1950s, static relays with numerous advantages were developed. The use of digital computers for protective relaying purposes has been engaging the attention of research and practicing engaging the attention of research and practicing engineerssince late 1960s and 1980s. Now, the microprocessor/mini computer-based relaying scheme, because of its numerous advantages such as self-checking feature and flexibility, has been widely used in power systems all over the world.The overall system protection is divided into following sections: (i) Generator protection, (ii) Transformer protection, (iii) Bus protection, (iv) Feeder protection, (v) Transmission line protection.Basic Requirements to Protective RelaysAny protection scheme, which is required to safeguard the power system components against abnormal conditions such as faults, consists basically of two elements: (i) Protective relay and (ii) Circuit breaker. The protective relay which is primarily the brain behind the whole scheme plays a very important role. Therefore proper care should be taken in selecting an appropriate protective relay which is reliable, efficient and fast in operation. The protective relay must satisfy the following requirements:(1) Since faults on a well designed and healthy system are normally rare, the relays are called upon to operate only occasionally. This means that the relaying scheme is normally idle and must operate whenever fault occurs. In other words, it must be reliable.(2) Since the reliability partly depends upon the maintenance, the relay must be easily maintainable.(3) The alliteration of the relay can be in two ways. One is the failure to operate in case a fault occurs and second is the relay operation when there is no fault. As a matter of fact, relay must operate if there isa fault and must not operate if there is no fault.(4) Relaying scheme must be sensitive enough to distinguish between normal and the faulty system.Protective RelaysThe function of the protective relays is to sense the fault and energize the trip coil of the circuit breaker. The following types of protective relays are used for the apparatus such as synchronous machines, bus bar, transformer and the other apparatus and transmission line protection.(1)Crosscurrent relays.(2)Under voltage relays.(3)Infrequence relays.(4)Directional relays.(5)Thermal relays.(6)Phase sequence relays such as (i) negative sequence relays and, (ii) zero sequence relays.(7)Differential relays and percentage differential relays.(8)Distance relays such as (i) plane impedance relays, (ii) angle impedance relays, i.e. Ohm or reactance relays, (iii) angle admittance relays, i.e. Ho relays and, (iv) offset and restricted relays.(9)Pilot relays such as (i) wire pilot relays, (ii) carrier channel pilot relays, (iii) microwave pilot relays.There are different types of the relaying scheme based on construction. They are: (i) electromagnet type, (ii) thermal relays, (iii) transactor relays, (iv) rectifier bridge relay, (v) electronic relays, (vi) static relays, (vii) digital relaying schemes.Faults and Their Damages on Power SystemsFaults on Transmission LinesBecause transmission lines are exposed to lightning and other atmospheric hazards, faults on them occur more frequently than those in apparatus. The types of faults taking place on a transmission line are listed, in the order of severity, as following:(1)3-φ fault (LLL fault) or 3-φ to ground fault (LLLG fault) with or without fault impedance. This fault which is most severe but least common is only one in number.(2)Double line to ground (LLG) fault with or without fault impedance. This fault is less severe but more common than 3-φ fault. However, this type of faults are three in number.(3)Line to line (LL) fault. This fault is more common but less severe than the above faults. These faults are also three in number.(4)Single line to ground (LG) fault. This fault is the least severe but the most common one. These faults are also three in number.From the above, we conclude that are four types of faults which are ten in number. The first three faults such as LLL or LLLG, LLG and LL faults involving two or more phases are known as phase fault while the fourth fault, namely, LG fault, is called ground fault. All of the line faults will bring the system into abnormal operating conditions, and may damage electrical equipment. Therefore, the faulty lines must be isolated from the system by protection relays.Faults in Synchronous MachinesGenerators are subjected to varieties of possible hazards when they are in operation. The possible hazards or faults which may occur in a synchronous generator can broadly be classified into two categories: (i) internal faults within the generator, (ii) abnormal operating and/or abnormal system conditions caused by external faults. Internal faults of a generator mainly include gustatory faults and rotor faults.Gustatory Faults----Within the gustatory winding, faults can occur due to failure of insulation (i.e. dielectric) and open circuit of conductor. Failure of insulation can lead to the short circuit between: (i) two or more phases, (ii) phase and core, (iii) two or more turns of the same phase (i.e. inter turn fault).Failure of insulation can occur due to over voltage, overheating caused by unbalanced loading, by overloading, by ventilation troubles, and by improper cooling of lubrication oil. It may also be caused by conductor movement due to forces exerted by short circuit currents or out of step operation. The most common fault in the gustatory winding is ground fault; about 85% of the faults are phase to ground faults in any generator winding. Phase to ground fault if persists may lead to phase to phase fault and even to phase-phase-phase fault (three-phase short circuit), which is the most severe fault though least common. The cause of over voltage which ultimately results into failure of insulation can be due to over speed of the prime mover, or due to defective voltage regulator; however, these days governors and voltage regulators act very fast and prevent any damage to the winding insulation.Rotor Faults----In the rotor winding also failure of insulation between field winding and core or two or more turns can occur. These faults may ultimately result in unbalanced currents and heating of the rotor. If the rotor is foregrounded, first earth fault does not show any effect but a second earth fault increases the current in the affected portion of winding which may cause distortion and permanent damage. It is advisable to open the field circuit breaker even with single earth fault to avoid second earth fault to avoid second earth fault so as to prevent local heating.Abnormal operating conditions / miscellaneous faults----There are a number of abnormal conditions which do not occur in the gustatory or rotor winding, but are undesirable since they can damage the generator. Each of these conditions is discussed in the following.(1)Loss of synchronic. This condition can occur either due to loss of field excitation or governor becomes defective. During out of step condition, as the swing angle between the generated voltage of the machineand that of other units in the system changes, the current in any such unit varies in magnitude. The current surges that result are cyclical in nature, their frequency being a function of reactive rate of slip of the poles in the machine. The resulted high peak currents and off-frequency operation can cause winding stresses, and pulsating torques which can excite mechanical resonances that can be potentially damaging to the generator and to the shifts. Thus generator should be tripped without any delay within the first slip cycle to avoid any major damage.(2)Over speed. The cause of over speed is sudden loss of a very large load; sometimes this happens due to tripping of circuit breaker near the generator end. In the case of steam turbine, the steam can be shut off immediately but in case of hydro turbine, the water flow cannot be stopped quickly, due to the mechanical and hydraulic inertia. The governor controls the over speeding so as to avoid any high voltage, high frequency and manically damage to the generators. The setting of an over speed rating may be 115% for steam turbines and 140% for hydro-disturbing.(3)Motoring. In a mufti-generator system, when prime mover fails to provide required speed, the generator may act as a motor, drawing power from the system, instead of supplying power. Generally motoring is prevented by sensitive reverse power relay which operates on about 0.5% reverse power.(4)Under speed. Due to failure of steam or water supply to the prime mover, the speed of the generator will reduce and if the reverse power relay fails, then under speed and/or infrequence relay comes into picture and trips the circuit breaker.(5)Loss of excitation. Excitation failure may be caused by a faulty field circuit breaker or failure of the exciter. It can be detected by an undercurrent dc relay. Due to failure of excitation, the synchronous generator may act as an induction generator thereby absorbing reactivepower (i.e. sink of reactive power). Turbine generator tends to overheat the rotor and the slot wedges under these conditions because of heavy currents in these parts and sometimes arcing occurs at metal wedges in the slots.(6)Over voltage. This may be caused due to over speed or elicitation when speed governor or voltage regulator fails to act as desired.(7)Gustatory overheating. Overheating may occur due to bearing failure, overloading, inadequate lubrication, or improper cooling of lubricating oil, etc. Overheating affects the dielectric strength of insulation.(8)External faults. Whenever abnormal conditions occur beyond the generator protection zone, the generator is also affected since the very source of power to the external fault is the generator itself. These conditions can be detected by the magnitude of negative sequence current, second harmonic current in field current and line crosscurrent relay.。

电力系统继电保护论文中英文资料Relay protection development present situation[Abstract ]reviewed our country electrical power system relay protection technological devil orpiment process，has outlined the microcomputer relay protection technology achievement, pro posed the future relay protection technological development tendency will be: Computerizes, n networked，protects, the control，the survey，the data communication integration and the artificial I intellectualization.[Key word ］relay protection present situation development，relay protections future development1 relay protection development present situationThe electrical power system rapid development to the relay protection proposed unceasingly t he new request，the electronic technology，computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology de velopment，therefore，the relay protection technology is advantageous, has completed the deve lopment 4 historical stage in more than 40 years time。

1、 外文原文（复印件）A: Fundamentals of Single-chip MicrocomputerT h e sin gle -ch ip mi c ro co m p u t e r is t h e cu lm in at io n of b ot h t h e d e ve lo p me nt of t h e d ig ita l co m p u t e r a n d t h e i nte g rated c ircu it a rgu ab l y t h e to w mo st s ign if i cant i nve nt i o n s of t h e 20t h c e nt u ry [1].T h ese to w t yp e s of arch ite ct u re are fo u n d in s in gle -ch ip m i cro co m p u te r. S o m e e mp l oy t h e sp l it p ro gra m /d at a m e m o r y of t h e H a r va rd arch ite ct u re , s h o wn in -5A , ot h e rs fo l lo w t h e p h i lo so p hy, wid e l y ad a p ted fo r ge n e ral -p u rp o se co m p u te rs an d m i cro p ro ce ss o rs , of m a kin g n o l o g i ca l d i st in ct i o n b et we e n p ro gra m an d d ata m e m o r y as in t h e P rin c eto n a rch ite ct u re , sh o wn in -5A.In ge n e ra l te r m s a s in g le -ch ip m ic ro co m p u t e r is ch a ra cte r ized b y t h e in co r p o rat io n of all t h e u n its of a co mp u te r into a s in gle d e vi ce , as s h o w n in F i g3-5A-3.-5A-1A Harvard type-5A. A conventional Princeton computerProgrammemory Datamemory CPU Input& Output unitmemoryCPU Input& Output unitResetInterruptsPowerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM).RO M is u su a l l y fo r t h e p e r m an e nt , n o n -vo lat i le sto rage of an ap p l i cat io n s p ro g ram .M a ny m i c ro co m p u te rs a n d m i cro co nt ro l le rs are inte n d ed fo r h i gh -vo lu m e ap p l i cat io n s a n d h e n ce t h e e co n o m i cal man u fa c t u re of t h e d e vi ces re q u ires t h at t h e co nt e nts of t h e p ro gra m me mo r y b e co mm i ed p e r m a n e nt l y d u r in g t h e m a n u fa ct u re of c h ip s . C lea rl y, t h i s imp l ies a r i go ro u s ap p ro a ch to ROM co d e d e ve lo p m e nt s in ce ch an ges can n o t b e mad e af te r m an u fa ct u re .T h i s d e ve l o p m e nt p ro ces s m ay i nvo l ve e mu l at i o n u sin g a so p h ist icated d e ve lo p m e nt syste m wit h a h ard wa re e mu l at i o n capab i l it y as we ll as t h e u s e of p o we rf u l sof t war e to o l s.So m e m an u fa ct u re rs p ro vi d e ad d it i o n a l ROM o p t io n s b y in clu d in g in t h e i r ran ge d e v ic es w it h (o r inte n d ed fo r u s e wit h ) u se r p ro g ram m a b le m e mo r y. T h e s im p lest of t h e se i s u su a l l y d e v i ce wh i ch can o p e rat e in a m i cro p ro ce s so r mo d e b y u s in g s o m e of t h e in p u t /o u t p u t l in es as an ad d res s a n d d ata b u s fo r a cc es sin g exte rn a l m e m o r y. T h is t yp e o f d e vi ce can b e h ave f u n ct i o n al l y as t h e s in gle ch ip m i cro co m p u t e r f ro m wh i ch it i s d e ri ved a lb e it wit h re st r icted I/O an d a m o d if ied exte rn a l c ircu it. T h e u s e of t h e se RO M le ss d e vi ces i s co mmo n e ve n in p ro d u ct io n circu i ts wh e re t h e vo lu m e d o e s n ot ju st if y t h e d e ve lo p m e nt co sts of cu sto m o n -ch ip ROM [2];t h e re ca n st i ll b e a si gn if i cant sav in g in I/O an d o t h e r ch ip s co m pared to a External Timing components System clock Timer/ Counter Serial I/O Prarallel I/O RAM ROMCPUco nve nt io n al m i c ro p ro ces so r b ased circ u it. M o re exa ct re p l a ce m e nt fo rRO M d e v ice s can b e o b tain ed in t h e fo rm of va ria nts w it h 'p i g g y-b a c k'E P ROM(E rasab le p ro gramm ab le ROM )s o cket s o r d e v ice s w it h E P ROMin stead of ROM 。

IEC 60364.4。

43-2008LOW—VOLTAGE ELECTRICAL INSTALLATIONS-3Part 4—43: Protection for safety Protection against overcurrent434。

2.2 A protective device may be placed on the supply side of the reduced cross—sectional area or another change made, provided that it possesses an operating characteristic such that it protects the wiring situated on the load side against short—circuit，in accordance with 434.5.2。

NOTE The requirements of 434.2。

2 may be met by the method given in Annex D。

434.3 Omission of devices for protection against short—circuitProvided that both of the following conditions are simultaneously fulfilled:• the wiring is installed in such a way as to reduce the risk of a short-circuit to a minimum （see item b) of 434.2。

1)，and• the wiring is not placed close to combustible material，devices for protection against short—circuit need not be provided for applications such as：a) conductors connecting generators, transformers, rectifiers，accumulator batteries to the associated control panels，the protective devices being placed in these panels；b）circuits where disconnection could cause danger for the operation of the installations concerned, such as those cited in 433.3.3;c) certain measuring circuits；d）at the origin of an installation where the distributor installs one or more devices providing protection against short-circuit and agrees that such a device affords protection to the part of the installation between the origin and the main distribution point of the installation where further short-circuit protection is provided。

电气工程的外文文献(及翻译)文献一：Electric power consumption prediction model based on grey theory optimized by genetic algorithms本文介绍了一种基于混合灰色理论与遗传算法优化的电力消耗预测模型。

该模型使用时间序列数据来建立模型，并使用灰色理论来解决数据的不确定性问题。

通过遗传算法的优化，模型能够更好地预测电力消耗，并取得了优异的预测结果。

此模型可以在大规模电力网络中使用，并具有较高的可行性和可靠性。

文献二：Intelligent control for energy-efficient operation of electric motors本文研究了一种智能控制方法，用于电动机的节能运行。

该方法提供了一种更高效的控制策略，使电动机能够在不同负载条件下以较低的功率运行。

该智能控制使用模糊逻辑方法来确定最佳的控制参数，并使用遗传算法来优化参数。

实验结果表明，该智能控制方法可以显著降低电动机的能耗，节省电能。

文献三：Fault diagnosis system for power transformers based on dissolved gas analysis本文介绍了一种基于溶解气体分析的电力变压器故障诊断系统。

通过对变压器油中的气体样品进行分析，可以检测和诊断变压器内部存在的故障类型。

该系统使用人工神经网络模型来对气体分析数据进行处理和分类。

实验结果表明，该系统可以准确地检测和诊断变压器的故障，并有助于实现有效的维护和管理。

文献四：Power quality improvement using series active filter based on iterative learning control technique本文研究了一种基于迭代研究控制技术的串联有源滤波器用于电能质量改善的方法。

Protection relayMicrocomuter-based RlayingA newer development in the of power system protection is the of computers (usually microcomputers) for relaying. Although computers provide the same protection as that supplied by conventional relays, there are some advantages to the use of computer-based relaying. The logic capability and application expansion possibilities for computer-based relaying is much greater than for electromechanical devices. Computer-based relaying samples the values of the current, voltage, and other items covered in the protection scheme several times a second, and by use of A/D converters, change these analog values to digital form and then send them to the computer. In the event of a fault, the computer can calculate the fault’s current values and characteristics, and settings can be changed merely by reprogramming. Computer-based relaying are also capable of locating faults, which has been one of the most popular features in their application. In addition, self-checking features can be built in and sequence of events information can be downloaded to remote computers for fast analysis of relaying operations. Computer-based relying system consists of subsystems with well defined functions. Although a specific subsystem may be different in some of its details, these subsystems are most likely to be incorporated in its design in some form. The block diagram in Figure 13-1 shows the principal subsystems of a computer-based relaying. The processor is the center of its organization. It is responsible for the execution of relaying programs, maintenance of various timing functions, and communicating with its peripheral equipment. Several types of memories are shown in Figure 13-1─each of them serves a specific need. The Random Access Memory (RAM) holds the input sample data as they are brought in and processed. The Read Only Memory (ROM) or Programmable Read Only Memory (PROM) is used to store the programs permanently. In some cases the programs may execute directly form the ROM if its read time is short enough. If this is not the case, the programs must be copied form the ROM into the RAM during an initialization stage, and then the real-time execution would take place form the RAM. The Erasable PROM (EPROM) is needed for storing certain parameters (such as the relaying settings) which may be changed form time to time, but once it is set it must remain fixed even if the power supply to the computer is interrupted. The relaying inputs are currents and voltages─or, to a lesser extent─digital signals indicating contact status. The analog signals must be converted to voltage signals suitable for conversion to digital form. The current and voltage signals obtained form current and voltage transformer secondary windings must be restricted to a full scale value of ±10 volts. The current inputs must be converted to voltages by resistive shunts. As the normal current transformer secondary currents may be as hundreds of amperes, shunts of resistance of a few milliohms are needed to produce the desired voltage for Analog to Digital Converter (ADC). An alternative arrangement would be to use an auxiliary current transformer to reduce the current to lower level. An auxiliary current transformer serves another function: that of providing electrical isolation between the min CT secondary and the computer input system. Since the digital computer can be programmed to perform several functions as long as it has the input and output signals needed for those functions. It is simple matter to the relaying computer to do many other substation tasks, for example, measuring and monitoring flows and voltages in transformers and transmission lines, controlling the opening and closing of circuit breakers and switches, providing backup for other devices that have failed, are functions that can be taken over by the relaying computer. With the programability and communication capability, the computer-based relaying offers yet another possible advantage that is not easily realizable in a conventional system. This is the ability to change the relay characteristics (settings) as the system conditions warrant it. With reasonable prospects of having affordable computer-based relaying which can be dedicated to single protection function, attention soon turned to the opportunities offered by computer-based relaying to integrate them into a substation, perhaps even a system-wide network. Integrated computer systems for substations which handle relaying, monitoring, and control tasks offer novel opportunities for improving overall system performance.Computer relaying The electric power industry has been one of the earliest users of the digital computer as a fundamental aid in the various design and analysis aspects of its activity. Computer-based systems have evolved to perform such complex tasks as generation control, economic dispatch (treated in chapter 11)and load-flow analysis for planning and operation , to name just a few application areas. research efforts directed at the prospect using digital computers to perform the tasks involved in power system protection date back to the mien-sixties and were motivated by the emergence of process-control computers a great deal of research is going on in this field, which is now referred to as computer relaying. Up to the early 1980s there had been no commercially availability protection systems offering digital computer-based relays. However, the availability of microprocessor technology has provided an impetus to computer relaying.*Microprocessors used as a replace*and solid state relays non provide a number of advantages while meeting the basic protection philosophy requirement of decentralization. There are many perceived benefits of a digital relaying system: 1. Economics: with the steady decrease in cost of digital hardware, coupled with the increase in cost of conventional relaying. It seems reasonable to assume that computer relaying is an attractive alternative. Software development cost can be expected to be evened out by utilizing economies of scale in producing microprocessors dedicated to basic relaying tasks. 2. Reliability: a digital system is continuously active providing a high level of a self-diagnosis to detect accidental failures within the digital relaying system. 3. Flexibility: revisions or modifications made necessary by changing operational conditions can be accommodated by utilizing the programmability features of a digital system. This would lead to reduced inventories of parts for repair and maintenance purposes 4. System interaction: the availability of digital hardware that monitors continuously the system performance at remote substations can enhance the level of information available to the control center. Post fault analysis of transient data can be performed on the basis of system variables monitored by the digital relay and recorded by the peripherals.The main elements of a digital computer-based relay are indicated in Figure 9-59. The input signals to the relay are analog (continuous) and digital power system variables. The digital inputs are of the order of five to ten and include status changes (on-off) of contacts and changes in voltage levels in a circuit. The analog signals are the 60-Hz currents and voltages. The number of analog signals needed depends on the relay function but is in the range of 3 to 30 in all cases. The analog signals are scaled down (attenuated) to acceptable computer input levels (10 volts maximum) and then converted to digital (discrete) form through analog/digital converters (ADC). These functions are performed in the block labeled “Analog Input Subsystem.” The digital output of the relay is available through the computer’s parallel output port, five-to-ten digital outputs are sufficient for most applications. The analog signals are sampled at a rate between 210 Hz to about 2000 Hz. The sampled signals are entered into the scratch pad (RAM) and are storedin a secondary data file for historical recording. A digital filter removes noise effects from the sampled signals. The relay logic program determines the functional operation of the relay and uses the filtered sampled signals to arrive at a trip or no trip decision which is then communicated to the system. The heart of the relay logic program is a relaying algorithm that is designed to perform the intended relay function such as over currents detection, differential protection, or distance protection, etc. It is not our intention in this introductory text to purse this involved in a relaying algorithm, we discuss next one idea for peak current detection that is the function of a digital over current relay.。

毕业论文（设计）英文翻译论文题目：电力系统的特殊保护方案系部名称：专业班级：学生姓名：学号：指导教师：教师职称：年月日电力系统的特殊保护方案Michal VARGONČÍK, Michal KOLCUN电气工程与信息学院，电力工程系科希策技术大学，Mäsiarska 74041 20科希策，电话.055/602 3650，电子邮件：Michal.Vargoncik @ tuke.sk 电气工程与信息学院，主管电力工程的科希策技术大学Mäsiarska 74041 20科希策，电话.055/602 3650，电子邮件：Michal.Kolcun @ tuke.sk摘要：这份报告初步研究,针对SPS(系统保护计划设计) 具有以下特点:1)广泛的途径;2)系统的广泛性对一个或多个危险的现象有缓解能力（如电压不稳，频率不稳定等）；3）紧急保护功能（由SCADA / EMS系统提供预防性保护）；4）执行控制，不仅监督电力系统行为变化的影响，并控制输入（减载负荷等）; 5 )综合公用事业。

这份报告简要总结可利用的信息在该地区的SPS控制器。

它是根据科学文献(会议论文集，期刊调查），部分作者的个人经验（公用事业和研发工作会议在这方面的代表）与重点上述列出的功能。

本报告的结构如下。

第一章简单介绍。

第二章定义问题和概述近期内的一些基本问题。

第三章分为几个电力系统的特殊保护方案部分。

每部分集中一个主要的不稳定现象，不稳定原则予以描述，采取相应的对策予以概述- 研究相应的事业和学术环境，强调最终结果。

第四章是结论。

关键词:不稳定、保护、故障、方案。

1．简介：在这篇文章中介绍了危险的电力系统不稳定地现象和定义，发展的历史背景；以及特别保护这种情况的简要分析，和现有安装的特点，SPS设计的主要准则。

2．广域系统：简称SPS是广域系统经常出现的术语。

广域系统有平台服务的各种用途。

它获取的数据（可同步）传达到一个中央位置并处理它们。