继电保护发展现状外文翻译

继电保护发展现状外文翻译
继电保护发展现状外文翻译

Relay protection development present situation

[ Abstract ] reviewed our country electrical power system relay protection technological development process, has outlined the microcomputer relay protection technology achievement, proposed the future relay protection technological development tendency will be: Computerizes, networked, protects, the control, the survey, the data communication integration and the artificial intellectualization.

[ Key word ] relay protection present situation development,relay protections future development

1 relay protection development present situation

The electrical power system rapid development to the relay protection proposed unceasingly the new request, the electronic technology, computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology development, therefore, the relay protection technology is advantageous, has completed the development 4 historical stage in more than 40 years time.

After the founding of the nation, our country relay protection discipline, the relay protection design, the relay manufacture industry and the relay protection technical team grows out of nothing, has passed through the path in about 10 years which advanced countries half century passes through. The 50's, our country engineers and technicians creatively absorption, the digestion, have grasped the overseas advanced relay protection equipment performance and the movement technology , completed to have the deep relay protection theory attainments and the rich movement experience relay protection technical team, and grew the instruction function to the national relay protection technical team's establishment. The acheng relay factory introduction has digested at that time the overseas advanced relay manufacture technology, has established our country relay manufacturing industry. Thus our country has completed the relay protection research, the design, the manufacture, the movement and the teaching complete system in the 60's. This is a time which the mechanical and electrical relay protection prospers, was our country relay protection technology development has laid the solid foundation.

From the end of the 50's, the transistor relay protection was starting to study. In the

60's to the 80's in are the times which the transistor relay protection vigorous development and widely uses. Tianjin University and the Nanjing electric power automation plant cooperation research 500kv transistor direction high frequency protection the transistor high frequency block system which develops with the Nanjing electric power automation research institute is away from the protection, moves on the Gezhou Dam 500 kv line , finished the 500kv line protection to depend upon completely from the overseas import time.

From the 70's, started based on the integration operational amplifier integrated circuit protection to study. Has formed the complete series to at the end of 80's integrated circuit protection,substitutes for the transistor protection gradually. The development, the production, the application the integrated circuit protects which to the beginning of the 90's still were in the dominant position, this was the integrated circuit protection time. The integrated electricity road work frequency conversion quantity direction develops which in this aspect Nanjing electric power automation research institute high frequency protected the vital role , the Tianjin University and the Nanjing electric power automation plant cooperation development integrated circuit phase voltage compensated the type direction high frequency protection also moves in multi- strip 220kv and on the 500kv line.

Our country namely started the computer relay protection research from the end of the 70's , the institutions of higher learning and the scientific research courtyard institute forerunner's function. Huazhong University of Science and Technology, southeast the university, the North China electric power institute, the Xian Jiaotong University, the Tianjin University, Shanghai Jiaotong University, the Chongqing University and the Nanjing electric power automation research institute one after another has all developed the different principle, the different pattern microcomputer protective device. In 1984 the original North China electric power institute developed the transmission line microcomputer protective device first through the appraisal, and in the system the find application, had opened in our country relay protection history the new page, protected the promotion for the microcomputer to pave the way. In the host equipment protection aspect, the generator which southeast the university and Huazhong University of Science and Technology develops loses magnetism protection, the generator protection and the generator?Bank of transformers protection also one after another in 1989, in 1994 through appraisal, investment movement. The Nanjing electric power automation research institute develops microcomputer line

protective device also in 1991 through appraisal. The Tianjin University and the Nanjing electric power automation plant cooperation development microcomputer phase voltage compensated the type direction high frequency protection, the Xian Jiaotong University and the Xu Chang relay factory cooperation development positive sequence breakdown component direction high frequency protection also one after another in 1993, in 1996 through the appraisal. Heres, the different principle, the different type microcomputer line and the host equipment protect unique, provided one batch of new generation of performance for the electrical power system fine, the function has been complete, the work reliable relay protection installment. Along with the microcomputer protective device research, in microcomputer aspect and so on protection software, algorithm has also yielded the very many theories result. May say started our country relay protection technology from the 90's to enter the time which the microcomputer protected.

2 relay protections future development

The relay protection technology future the tendency will be to computerizes, networked, the intellectualization, will protect, the control, the survey and the data communication integration development.

2.1 computerizes

Along with the computer hardware swift and violent development, the microcomputer protection hardware also unceasingly is developing. The original North China electric power institute develops the microcomputer line protection hardware has experienced 3 development phases: Is published from 8 lists cpu structure microcomputer protection, does not develop to 5 years time to the multi- cpu structure, latter developed to the main line does not leave the module the big modular structure, the performance enhances greatly, obtained the widespread application. Huazhong University of Science and Technology develops the microcomputer protection also is from 8 cpu, develops to take the labor controlling machine core partially as the foundation 32 microcomputers protection.

The Nanjing electric power automation research institute from the very beginning has developed 16 cpu is the foundation microcomputer line protection, obtained the big area promotion, at present also is studying 32 protections hardware system. Southeast

the university develops the microcomputer host equipment protects the hardware also passed through improved and the enhancement many times. The Tianjin University from the very beginning is the development take more than 16 cpu as the foundation microcomputer line protection, in 1988 namely started to study take 32 digital signals processor (dsp) as the foundation protection, the control, the survey integration microcomputer installment, at present cooperated with the Zhuhai Jin automatic equipment company develops one kind of function complete 32 big modules, a module was a minicomputer. Uses 32 microcomputers chips only to focus by no means on the precision, because of the precision the a/d switch resolution limit, is surpassed time 16 all is accepts with difficulty in the conversion rate and the cost aspect; 32 microcomputers chips have the very high integration rate more importantly, very high operating frequency and computation speed, very big addressing space, rich command system and many inputs outlet. The cpu register, the data bus, the address bus all are 32, has the memory management function, the memory protection function and the duty transformation function, and (cache) and the floating number part all integrates the high speed buffer in cpu.

The electrical power system the request which protects to the microcomputer enhances unceasingly, besides protection basic function, but also should have the large capacity breakdown information and the data long-term storage space, the fast data processing function, the formidable traffic capacity, with other protections, the control device and dispatches the networking by to share the entire system data, the information and the network resources ability, the higher order language programming and so on. This requests the microcomputer protective device to have is equal to a pc machine function. In the computer protection development initial period, once conceived has made the relay protection installment with a minicomputer. At that time because the small machine volume big, the cost high, the reliability was bad, this tentative plan was not realistic. Now, with the microcomputer protective device size similar labor controlling machine function, the speed, the storage capacity greatly has surpassed the same year small machine, therefore, made the relay protection with complete set labor controlling machine the opportunity already to be mature, this will be one of development directions which the microcomputer protected. The Tianjin University has developed the relay protection installment which Cheng Yongtong microcomputer protective device structure quite same not less than one kind of labor controlling machine performs to change artificially becomes. This kind of equipment

merit includes: has the 486pc machine complete function, can satisfy each kind of function request which will protect to current and the future microcomputer. size and structure and present microcomputer protective device similar, the craft excellent, quakeproof, guards against has been hot, guards against electronmagetic interference ability, may move in the very severe working conditions, the cost may accept. uses the std main line or the pc main line, the hardware modulation, may select the different module wilfully regarding the different protection, the disposition nimble, is easy to expand.

Relay protection installment , computerizes is the irreversible development tendency. How but to satisfies the electrical power system request well, how further enhances the relay protection the reliability, how obtains the bigger economic efficiency and the social efficiency, still must conduct specifically the thorough research.

2.2 networked

The computer network has become the information age as the information and the data communication tool the technical prop, caused the human production and the social life appearance has had the radical change. It profoundly is affecting each industry domain, also has provided the powerful means of communication for each industry domain. So far, besides the differential motion protection and the vertical association protection, all relay protections installment all only can respond the protection installment place electricity spirit. The relay protection function also only is restricted in the excision breakdown part, reduces the accident to affect the scope. This mainly is because lacks the powerful data communication method. Overseas already had proposed the system protection concept, this in mainly referred to the safe automatic device at that time. Because the relay protection function not only is restricted in the excision breakdown part and the limit accident affects the scope (this is most important task), but also must guarantee the entire system the security stable movement. This requests each protection unit all to be able to share the entire system the movement and the breakdown information data, each protection unit and the superposition brake gear in analyze these information and in the data foundation the synchronized action, guarantees the system the security stable movement. Obviously, realizes this kind of system protection basic condition is joins the entire system each main equipment protective device with the computer network, that is realization

microcomputer protective device networked. This under the current engineering factor is completely possible.

Regarding the general non- system protection, the realization protective device computer networking also has the very big advantage. The relay protection equipment can obtain system failure information more, then to the breakdown nature, the breakdown position judgment and the breakdown distance examination is more accurate. Passed through the very long time to the auto-adapted protection principle research, also has yielded the certain result, but must realize truly protects to the system movement way and the malfunction auto-adapted, must obtain the more systems movement and the breakdown information, only then realization protection computer networked, can achieve this point.

Regarding certain protective device realization computer networkings, also can enhance the protection the reliability. The Tianjin University in 1993 proposed in view of the future Three Gorges hydroelectric power station 500kv ultrahigh voltage multi- return routes generatrix one kind of distributional generatrix protection principle, developed successfully this kind of equipment initially. Its principle is disperses the traditional central generatrix protection certain (with to protect generatrix to return way to be same) the generatrix protection unit, the dispersible attire is located in on various return routes protection screen, each protection unit joins with the computer network, each protection unit only inputs this return route the amperage, after transforms it the digital quantity, transmits through the computer network for other all return routes protection unit, each protection unit acts according to this return route the amperage and other all return routes amperage which obtains from the computer network, carries on the generatrix differential motion protection the computation, if the computed result proof is the generatrix interior breakdown then only jumps the book size return route circuit breaker, Breakdown generatrix isolation. When generatrix area breakdown, each protection unit all calculates for exterior breakdown does not act. This kind the distributional generatrix protection principle which realizes with the computer network, has the high reliability compared to the traditional central generatrix protection principle. Because if a protection unit receives the disturbance or the miscalculation when moves by mistake, only can wrongly jump the book size return route, cannot create causes the generatrix entire the malignant accident which excises, this regarding looks like the Three Gorges power plant to have the ultrahigh voltage generatrix the system key position to be extremely

important.

By above may know, microcomputer protective device may enhance the protection performance and the reliability greatly, this is the microcomputer protection development inevitable trend.

2.3 protections, control, survey, data communication integrations

In realization relay protection computerizing with under the condition, the protective device is in fact a high performance, the multi-purpose computer, is in an entire electrical power system computer network intelligent terminal. It may gain the electrical power system movement and breakdown any information and the data from the net, also may protect the part which obtains it any information and the data transfer for the network control center or no matter what a terminal. Therefore, each microcomputer protective device not only may complete the relay protection function, moreover in does not have in the breakdown normal operation situation also to be possible to complete the survey, the control, the data communication function, that is realization protection, control, survey, data communication integration.

At present, in order to survey, the protection and the control need, outdoor transformer substation all equipment, like the transformer, the line and so on the secondary voltage, the electric current all must use the control cable to direct to . Lays the massive control cable not only must massively invest, moreover makes the secondary circuit to be extremely complex. But if the above protection, the control, the survey, the data communication integration computer installation, will install in outdoor transformer substation by the protection device nearby, by the protection device voltage, the amperage is changed into after this installment internal circulation the digital quantity, will deliver through the computer network, then might avoid the massive control cable. If takes the network with the optical fiber the transmission medium, but also may avoid the electronmagetic interference. Now the photoelectric current mutual inductor (ota) and the photovoltage mutual inductor (otv) in the research trial stage, future inevitably obtained the application in the electrical power system. In uses ota and in the otv situation, the protective device should place is apart from ota and the otv recent place, that is should place by the protection device nearby. Ota and the otv light signal inputs after this integration installment in and transforms the electrical signal, on the one hand serves as the protection the computation

judgment; On the other hand took the survey quantity, delivers through the network. May to deliver from through the network by the protection device operation control command this integrated installment, carries out the circuit breaker operation from this the integrated installment. In 1992 the Tianjin University proposed the protection, the control, the survey, the correspondence integration question, and has developed take the tms320c25 digital signal processor (dsp) as a foundation protection, the control, the survey, the data communication integration installment.

2.4 intellectualizations

In recent years, the artificial intelligence technology like nerve network, the genetic algorithms, the evolution plan, the fuzzy logic and so on all obtained the application in electrical power system each domain, also started in the relay protection domain application research. The nerve network is one non-linear mapping method, very many lists the complex non-linear problem with difficulty which the equation or solves with difficulty, the application nerve network side principle may be easily solved. For example exhibits in the situation in the transmission line two sides systems electric potential angle to occur after the transition resistance short-circuits is a non-linear problem, very difficult correctly to make the breakdown position from the protection the distinction, thus creates moves by mistake or resists to move; If thinks after the network method, passes through the massive breakdowns sample training, so long as the sample centralism has fully considered each kind of situation, then in breaks down time any all may correctly distinguish. Other like genetic algorithms, the evolution plan and so on also all have its unique solution complex question the ability. May cause the solution speed these artificial intelligence method suitable unions to be quicker. The Tianjin University carries on the nerve network type relay protection from 1996 the research, has yielded the preliminary result ]. May foresee, the artificial intelligence technology must be able to obtain the application in the relay protection domain, by solves the problem which solves with difficulty with the conventional method.

3 Conclution

Since the founding of China's electric power system protection technology has undergone four times. With the rapid development of power systems and computer

technology, communications technology, relay technology faces the further development of the trend. Domestic and international trends in the development of protection technologies: computerization, networking, protection, control, measurement, data communications integration and artificial intelligence, which made protection workers difficult task, but also opened up the activities of vast.

继电保护发展现状

【摘要】回顾我国电力系统继保护技术发展的过程中,概述了微机继电保护技术的成就,提出了未来继电保护技术发展趋势将是:计算机化,电网络化,保护,控制,调查结果显示,数据通信一体化和人工智能化。

【关键词】继电保护现状发展,继电保护的未来发展

1 继电保护发展现状

电力系统的迅速发展对继电保护不断提出新的要求,电子技术,计算机技术的快速发展不断为继电保护技术的发展注入新的活力,因此,继电保护技术是有利的,在40多年的时间里已完成发展了4个历史阶段。

建国后,我国继电保护学科、继电保护设计、继电器制造工业和继电保护技术队伍从无到有,在大约10年的时间里走过了先进国家半个世纪走过的道路。50年代,我国工程技术人员创造性地吸收、消化、掌握了国外先进的继电保护设备性能和运行技术,建成了一支具有深厚继电保护理论造诣和丰富运行经验的继电保护技术队伍,对全国继电保护技术队伍的建立和成长起了指导作用。阿城继电器厂引进消化了当时国外先进的继电器制造技术,建立了我国自己的继电器制造业。因而在60年代中我国已建成了继电保护研究、设计、制造、运行和教学的完整体系。这是机电式继电保护繁荣的时代,为我国继电保护技术的发展奠定了坚实基础。

自50年代末,晶体管继电保护已在开始研究。60年代中到80年代中是晶体管继电保护蓬勃发展和广泛采用的时代。其中天津大学与南京电力自动化设备厂合作研究的500kv晶体管方向高频保护和南京电力自动化研究院研制的晶体管高频闭锁距离保护,运行于葛洲坝500 kv线路上,结束了500kv线路保护完全依靠从国外进口的时代。

在此期间,从70年代中,基于集成运算放大器的集成电路保护已开始研究。到80年代末集成电路保护已形成完整系列,逐渐取代晶体管保护。到90年代初集成电路保护的研制、生产、应用仍处于主导地位,这是集成电路保护时代。在这方面南京电力自动化研究院研制的集成电路工频变化量方向高频保护起了重要

作用,天津大学与南京电力自动化设备厂合作研制的集成电路相电压补偿式方向高频保护也在多条220kv和500kv线路上运行。

我国从70年代末即已开始了计算机继电保护的研究,高等院校和科研院所起着先导的作用。华中理工大学、东南大学、华北电力学院、西安交通大学、天津大学、上海交通大学、重庆大学和南京电力自动化研究院都相继研制了不同原理、不同型式的微机保护装置。1984年原华北电力学院研制的输电线路微机保护装置首先通过鉴定,并在系统中获得应用,揭开了我国继电保护发展史上新的一页,为微机保护的推广开辟了道路。在主设备保护方面,东南大学和华中理工大学研制的发电机失磁保护、发电机保护和发电机?变压器组保护也相继于1989、1994年通过鉴定,投入运行。南京电力自动化研究院研制的微机线路保护装置也于1991年通过鉴定。天津大学与南京电力自动化设备厂合作研制的微机相电压补偿式方向高频保护,西安交通大学与许昌继电器厂合作研制的正序故障分量方向高频保护也相继于1993、1996年通过鉴定。至此,不同原理、不同机型的微机线路和主设备保护各具特色,为电力系统提供了一批新一代性能优良、功能齐全、工作可靠的继电保护装置。随着微机保护装置的研究,在微机保护软件、算法等方面也取得了很多理论成果。可以说从90年代开始我国继电保护技术已进入了微机保护的时代。

2 继电保护的未来发展

继电保护技术未来趋势是向计算机化,网络化,智能化,保护、控制、测量和数据通信一体化发展。

2.1计算机化

随着计算机硬件的迅猛发展,微机保护硬件也在不断发展。原华北电力学院研制的微机线路保护硬件已经历了3个发展阶段:从8位单cpu结构的微机保护问世,不到5年时间就发展到多cpu结构,后又发展到总线不出模块的大模块结构,性能大大提高,得到了广泛应用。华中理工大学研制的微机保护也是从8位cpu,发展到以工控机核心部分为基础的32位微机保护。

南京电力自动化研究院一开始就研制了16位cpu为基础的微机线路保护,已得到大面积推广,目前也在研究32位保护硬件系统。东南大学研制的微机主

设备保护的硬件也经过了多次改进和提高。天津大学一开始即研制以16位多cpu 为基础的微机线路保护,1988年即开始研究以32位数字信号处理器(dsp)为基础的保护、控制、测量一体化微机装置,目前已与珠海晋电自动化设备公司合作研制成一种功能齐全的32位大模块,一个模块就是一个小型计算机。采用32位微机芯片并非只着眼于精度,因为精度受a/d转换器分辨率的限制,超过16位时在转换速度和成本方面都是难以接受的;更重要的是32位微机芯片具有很高的集成度,很高的工作频率和计算速度,很大的寻址空间,丰富的指令系统和较多的输入输出口。cpu的寄存器、数据总线、地址总线都是32位的,具有存储器管理功能、存储器保护功能和任务转换功能,并将高速缓存(cache)和浮点数部件都集成在cpu内。

电力系统对微机保护的要求不断提高,除了保护的基本功能外,还应具有大容量故障信息和数据的长期存放空间,快速的数据处理功能,强大的通信能力,与其它保护、控制装置和调度联网以共享全系统数据、信息和网络资源的能力,高级语言编程等。这就要求微机保护装置具有相当于一台pc机的功能。在计算机保护发展初期,曾设想过用一台小型计算机作成继电保护装置。由于当时小型机体积大、成本高、可靠性差,这个设想是不现实的。现在,同微机保护装置大小相似的工控机的功能、速度、存储容量大大超过了当年的小型机,因此,用成套工控机作成继电保护的时机已经成熟,这将是微机保护的发展方向之一。天津大学已研制成用同微机保护装置结构完全相同的一种工控机加以改造作成的继电保护装置。这种装置的优点有:(1)具有486pc机的全部功能,能满足对当前和未来微机保护的各种功能要求。(2)尺寸和结构与目前的微机保护装置相似,工艺精良、防震、防过热、防电磁干扰能力强,可运行于非常恶劣的工作环境,成本可接受。(3)采用std总线或pc总线,硬件模块化,对于不同的保护可任意选用不同模块,配置灵活、容易扩展。

继电保护装置的微机化、计算机化是不可逆转的发展趋势。但对如何更好地满足电力系统要求,如何进一步提高继电保护的可靠性,如何取得更大的经济效益和社会效益,尚须进行具体深入的研究。

2.2网络化

计算机网络作为信息和数据通信工具已成为信息时代的技术支柱,使人类

生产和社会生活的面貌发生了根本变化。它深刻影响着各个工业领域,也为各个工业领域提供了强有力的通信手段。到目前为止,除了差动保护和纵联保护外,所有继电保护装置都只能反应保护安装处的电气量。继电保护的作用也只限于切除故障元件,缩小事故影响范围。这主要是由于缺乏强有力的数据通信手段。国外早已提出过系统保护的概念,这在当时主要指安全自动装置。因继电保护的作用不只限于切除故障元件和限制事故影响范围(这是首要任务),还要保证全系统的安全稳定运行。这就要求每个保护单元都能共享全系统的运行和故障信息的数据,各个保护单元与重合闸装置在分析这些信息和数据的基础上协调动作,确保系统的安全稳定运行。显然,实现这种系统保护的基本条件是将全系统各主要设备的保护装置用计算机网络联接起来,亦即实现微机保护装置的网络化。这在当前的技术条件下是完全可能的。

对于一般的非系统保护,实现保护装置的计算机联网也有很大的好处。继电保护装置能够得到的系统故障信息愈多,则对故障性质、故障位置的判断和故障距离的检测愈准确。对自适应保护原理的研究已经过很长的时间,也取得了一定的成果,但要真正实现保护对系统运行方式和故障状态的自适应,必须获得更多的系统运行和故障信息,只有实现保护的计算机网络化,才能做到这一点。

对于某些保护装置实现计算机联网,也能提高保护的可靠性。天津大学1993年针对未来三峡水电站500kv超高压多回路母线提出了一种分布式母线保护的原理,初步研制成功了这种装置。其原理是将传统的集中式母线保护分散成若干个(与被保护母线的回路数相同)母线保护单元,分散装设在各回路保护屏上,各保护单元用计算机网络联接起来,每个保护单元只输入本回路的电流量,将其转换成数字量后,通过计算机网络传送给其它所有回路的保护单元,各保护单元根据本回路的电流量和从计算机网络上获得的其它所有回路的电流量,进行母线差动保护的计算,如果计算结果证明是母线内部故障则只跳开本回路断路器,将故障的母线隔离。在母线区外故障时,各保护单元都计算为外部故障均不动作。这种用计算机网络实现的分布式母线保护原理,比传统的集中式母线保护原理有较高的可靠性。因为如果一个保护单元受到干扰或计算错误而误动时,只能错误地跳开本回路,不会造成使母线整个被切除的恶性事故,这对于象三峡电站具有超高压母线的系统枢纽非常重要。

由上述可知,微机保护装置网络化可大大提高保护性能和可靠性,这是微机保护发展的必然趋势。

2.3保护、控制、测量、数据通信一体化

在实现继电保护的计算机化和网络化的条件下,保护装置实际上就是一台高性能、多功能的计算机,是整个电力系统计算机网络上的一个智能终端。它可从网上获取电力系统运行和故障的任何信息和数据,也可将它所获得的被保护元件的任何信息和数据传送给网络控制中心或任一终端。因此,每个微机保护装置不但可完成继电保护功能,而且在无故障正常运行情况下还可完成测量、控制、数据通信功能,亦即实现保护、控制、测量、数据通信一体化。

目前,为了测量、保护和控制的需要,室外变电站的所有设备,如变压器、线路等的二次电压、电流都必须用控制电缆引到主控室。所敷设的大量控制电缆不但要大量投资,而且使二次回路非常复杂。但是如果将上述的保护、控制、测量、数据通信一体化的计算机装置,就地安装在室外变电站的被保护设备旁,将被保护设备的电压、电流量在此装置内转换成数字量后,通过计算机网络送到主控室,则可免除大量的控制电缆。如果用光纤作为网络的传输介质,还可免除电磁干扰。现在光电流互感器(ota)和光电压互感器(otv)已在研究试验阶段,将来必然在电力系统中得到应用。在采用ota和otv的情况下,保护装置应放在距ota 和otv最近的地方,亦即应放在被保护设备附近。ota和otv的光信号输入到此一体化装置中并转换成电信号后,一方面用作保护的计算判断;另一方面作为测量量,通过网络送到主控室。从主控室通过网络可将对被保护设备的操作控制命令送到此一体化装置,由此一体化装置执行断路器的操作。1992年天津大学提出了保护、控制、测量、通信一体化问题,并研制了以tms320c25数字信号处理器(dsp)为基础的一个保护、控制、测量、数据通信一体化装置。

2.4智能化

近年来,人工智能技术如神经网络、遗传算法、进化规划、模糊逻辑等在电力系统各个领域都得到了应用,在继电保护领域应用的研究也已开始[7]。神经网络是一种非线性映射的方法,很多难以列出方程式或难以求解的复杂的非线性问题,应用神经网络方法则可迎刃而解。例如在输电线两侧系统电势角度摆开情况下发生经过渡电阻的短路就是一非线性问题,距离保护很难正确作出故障位

置的判别,从而造成误动或拒动;如果用神经网络方法,经过大量故障样本的训练,只要样本集中充分考虑了各种情况,则在发生任何故障时都可正确判别。其它如遗传算法、进化规划等也都有其独特的求解复杂问题的能力。将这些人工智能方法适当结合可使求解速度更快。天津大学从1996年起进行神经网络式继电保护的研究,已取得初步成果。可以预见,人工智能技术在继电保护领域必会得到应用,以解决用常规方法难以解决的问题。

3结束语

建国以来,我国电力系统继电保护技术经历了4个时代。随着电力系统的高速发展和计算机技术、通信技术的进步,继电保护技术面临着进一步发展的趋势。国内外继电保护技术发展的趋势为:计算机化,网络化,保护、控制、测量、数据通信一体化和人工智能化,这对继电保护工作者提出了艰巨的任务,也开辟了活动的广阔天地。

继电保护的发展现状

Relay protection development present situation [ Key word ] relay protection present situation development,relay protections future development. [ Abstract ] reviewed our country electrical power system relay protection technological development process, has outlined the microcomputer relay protection technology achievement, proposed the future relay protection technological development tendency will be: Computerizes, networked, protects, the control, the survey, the data communication integration and the artificial intellectualization. 1 relay protection development present situation. The electrical power system rapid development to the relay protection proposed unceasingly the new request, the electronic technology, computer technology and the communication rapid development unceasingly has poured into the new vigor for the relay protection technology development, therefore, the relay protection technology is advantageous, has completed the development 4 historical stage in more than 40 years time. After the founding of the nation, our country relay protection discipline, the relay protection design, the relay manufacture industry and the relay protection technical team grows out of nothing, has passed through the path in about 10 years which advanced countries half century passes through. The 50's, our country engineers and technicians creatively absorption, the digestion, have grasped the overseas advanced relay protection equipment performance and the movement technology , completed to have the deep relay protection theory attainments and the rich movement experience relay protection technical team, and grew the instruction function to the national relay protection technical team's establishment. The acheng relay factory introduction has digested at that time the overseas advanced relay manufacture technology, has established our country relay manufacturing industry. Thus our country has completed the relay protection research, the design, the manufacture, the movement and the teaching complete system in the 60's. This is a time which the mechanical and electrical relay protection prospers, was our country relay protection technology development has laid the solid foundation.

旅游服务贸易外文翻译文献

旅游服务贸易外文翻译文献(文档含英文原文和中文翻译)

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的理论基础已经不太在学术文献进行分析。因此,一个国家国际竞争力的性质,效益和局限性仍然含糊不清(科尔德威尔,2000,克鲁格曼,1994, 1996)。 国际竞争力,是指一个国家在货物和服务贸易方面巩固和保持贸易优势相对于世界其他地区的贸易优势。 每当一个国家的经济福利通过贸易流量的增加,或通过从初始平衡状态的贸易条件的改变而增加,他的国际竞争力都会得到提高(科尔德威尔,2000)。 贸易理论表示,经济福利依赖于一个国家有比较优势的货物和服务的生产。这实际上意味着当生产符合一国的比较优势的情况时国际竞争力能得到保障。如果一国能在国际上表现良好并在出口市场竞争成功,这可能就是他们健全的国际竞争力的标志。 因此,在国际上,竞争力定义为一个经济体能够吸引其出口需求和投资供给需求的能力和在所有社会规范内提升公民生活水平的能力。这反过来又取决于宏观和微观经济政策,影响生产的经济生产率要素和经营成本的法规和制度。 一个可用的文献回顾和实证证据支持国际竞争力可以解释为在一定程度上,一个国家的出口能力这一观点(道乐和沃尔夫,1993, 格博格等. 2004)。还有就是,事实上,是出口表现和国际竞争力之间的循环关系。出口是国际竞争力的第一衡量指标。出口情况的改善会导致了一个国家的竞争力提升。这种效果是一个企业的技能,知识,创新和运用新技术并能够在一个成功的商业方式中利用技术机会等的结果。 另一方面,为了在竞争激烈的全球市场努力成功实现出口,一个国家被迫提高竞争力。更具竞争力的国家,它的经济更强大。因此,它更有能力在全球市场竞争,以吸引具有较高的知识,技能,水平人们去购买新技术等,

电力系统继电保护外文翻译

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