Power Supply and Distribution SystemABSTRACT: The basic function of the electric power system is to transport the electric power towardscustomers..The l0kV electric distribution net is a key point that connects the power supply with the electricityusing on the industry, business and daily-life. For the electric power, allcostumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable.To improve the reliability of the power supply network, we must increase the investment cost of the network construction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic,between the investment and the loss by calculating the investment on power net and the loss brought from power-off.KEYWORDS:power supply and distribution, power distribution reliability，reactive compensation, load distributionThe revolution of electric power system has brought a new big round construction,which is pushing the greater revolution of electric power technique along with the application of new technique and advanced equipment. Especially, the combination of the information technique and electric power technique, to great ex- tent, has improved reliability on electric quality and electric supply. The technical development decreases the cost on electric construction and drives innovation of electric network. On the basis of national and internatio- nal advanced electricknowledge, the dissertation introduces the research hotspot for present electric power sy- etem as following.Firstly, This dissertation introduces the building condition of distribution automation(DA), and brings forward two typical construction modes on DA construction, integrative mode and fission mode .It emphasize the DA structure under the condition of the fission mode and presents the system configuration, the main station scheme, the feeder scheme, the optimized communication scheme etc., which is for DA research reference.Secondly, as for the (DA) trouble measurement, position, isolation and resume, This dissertation analyzes the changes of pressure and current for line problem, gets math equation by educing phase short circuit and problem position under the condition of single-phase and works out equation and several parameter s U& , s I& and e I& table on problem . It brings out optimized isolation and resume plan, realizes auto isolation and network reconstruction, reduces the power off range and time and improves the reliability of electric power supply through problem self- diagnoses and self-analysis. It also introduces software flow and use for problem judgement and sets a model on network reconstruction and computer flow.Thirdly, electricity system state is estimated to be one of the key techniques in DA realization. The dissertation recommends the resolvent of bad measurement data and structure mistake on the ground of describing state estimate way. It also advances a practical test and judging way on topology mistake in state estimate about bad data test and abnormity in state estimate as well as the problem and effect on bad data from state measure to state estimate .As for real time monitor and control problem, the dissertation introduces a new way to solve them by electricity break and exceptional analysis, and the way has been tested in Weifang DA.Fourthly, about the difficulty for building the model of load forecasting, big parameter scatter limit and something concerned, the dissertation introduces some parameters, eg. weather factor, date type and social environment effect based on analysis of routine load forecasting and means. It presents the way for electricity load forecasting founded on neural network(ANN),which has been tested it’s validity by example and made to be good practical effect.Fifthly, concerning the lack of concordant wave on preve nting concordant wave and non-power compensation and non-continuity on compensation, there is a topology structure of PWM main circuit and nonpower theory on active filter the waves technique and builds flat proof on the ground of Saber Designer and proves to be practical. Meanwhile, it analyzes and designs the way of non-power need of electric network tre- nds and decreasing line loss combined with DA, which have been tested its objective economic benefit throu- gh counting example.Sixthly, not only do the dissertation design a way founded on the magrginal electric price fitted to our present national electric power market with regards to future trends of electric power market in China and fair trade under the government surveillance, that is group competitio n in short-term trade under the way of grouped price and quantity harmony, but also puts forward combination arithmetic, math model of trading plan and safty economical restriction. It can solve the original contradiction between medium and long term contract price and short term competitive price with improvement on competitive percentage and cut down the unfair income difference of electric factory, at the same time, it can optimize the electric limit for all electric factories and reduce the total purchase charge of electric power from burthen curve of whole electric market network.The distribution network is an important link among the power system. Its neutral grounding mode and operation connects security and stability of the power system directly. At the same time, the problem about neutral grounding is associated with national conditions, natural environment, device fabrication and operation. For example, the activity situation of the thunder and lightning, insulating structure and the peripheral interference will influence the choice of neutral grounding mode Conversely, neutral grounding mode affects design, operation, debugs and developing. Generally in the system higher in grade in the voltage, the insulating expenses account for more sizable proportion at the total price of the equipment. It is very remarkable to bring the economic benefits by reducing the insulating level. Usually such system adopt the neutral directly grounding and adopt the autoreclosing to guarantee power supply reliability. On the contrary, the system which is lower in the voltage adopts neutral none grounding to raise power supply reliability. So it is an important subject to make use of new- type earth device to apply to the distribution network under considering the situation in such factors of various fields as power supply reliability, safety factor, over-voltage factor, the choice of relay protection, investment cost, etc.The main work of this paper is to research and choice the neutral grounding mode of the l0kV distribution network. The neutral grounding mode of the l0kV network mainly adopts none grounding, grounding by arc suppressing coil, grounding by reactance grounding and directly grounding. The best grounding mode is confirmed through the technology comparison. It can help the network run in safety and limit the earth electric arc by using auto-tracking compensate device and using the line protection with the detection of the sensitive small ground current. The paper introduces and analyzes the characteristic of all kind of grounding modesabout l0kV network at first. With the comparison with technological and economy, the conclusion is drawn that the improved arc suppressing coil grounding mode shows a very big development potential.Then, this paper researches and introduces some operation characteristics of the arc suppressing coil grounding mode of the l0kV distribution network. And then the paper put emphasis on how to extinguish the earth electric arc effectively by utilizing the resonance principle. This paper combines the development of domestic and international technology and innovative achievement, and introduces the computer earth protection and autotracking compensate device. It proves that the improved arc suppressing coil grounding mode have better operation characteristics in power supply reliability, personal security, security of equipment and interference of communication. The application of the arc suppressing coil grounding mode is also researched in this paper.Finally, the paper summarizes this topic research. As a result of the domination of the arc suppressing coil grounding mode, it should be more popularized and applied in the distribution network in the future.The way of thinking, project and conclusions in this thesis have effect on the research to choose the neutral grounding mode not only in I0kV distribution network but also in other power system..The basic function of the electric power system is to transport the electric power towards customers. The l0kV electric distribution net is a key point that connects the power supply with the electricity using on the industry, business and daily-life. For the electric power, all costumers expect to pay the lowest price for the highest reliability, but don't consider that it's self-contradictory in the co-existence of economy and reliable. To improve the reliability of the power supply network, we must increase the investment cost of the network con-struction But, if the cost that improve the reliability of the network construction, but the investment on this kind of construction would be worthless if the reducing loss is on the power-off is less than the increasing investment on improving the reliability .Thus we find out a balance point to make the most economic, between the investment and the loss by calculating the investment on power net and the loss brought from power-off. The thesis analyses on the economic and the reliable of the various line modes, according to the characteristics various line modes existed in the electric distribution net in foshan..First, the thesis introduces as the different line modes in the l0kV electric distribution net and in some foreign countries. Making it clear tow to conduct analyzing on the line mode of the electric distribution net, and telling us how important and necessary that analyses are.Second, it turns to the necessity of calculating the number of optimization subsection, elaborating how it influences on the economy and reliability. Then by building up the calculation mode of the number of optimization subsection it introduces different power supply projects on the different line modes in brief. Third, it carries on the calculation and analyses towards the reliability and economy of the different line modes of electric distribution net, describing drafts according by the calculation. Then it makes analysis and discussion on the number of optimization subsection.At last, the article make conclusion on the economy and reliability of different line modes, as well as, its application situation. Accordion to the actual circumstance, the thesis puts forward the beneficial suggestion on the programming and construction of the l0kV electric distribution net in all areas in foshan. Providing the basic theories and beneficial guideline for the programming design of the lOkV electricdistribution net and building up a solid net, reasonable layout, qualified safe and efficiently-worked electric distribution net.References[1] Wencheng Su. Factories power supply [M]. Machinery Industry Publishing House. 1999.9[2] Jiecai Liu. Factories power supply design guidance [M]. Machinery Industry Publishing House.1999.12[3] Power supply and distribution system design specifications[S].China plans Press. 1996[4] Low-voltage distribution design specifications [S].China plans Press. 1996.6Relay protection development present situationInstitution:Tianjin Electric Power Association[Abstract]reviewed our country electrical power system relay protec tion technological development process,has outlined the microcomputer re lay protection technology achievement,proposed the future relay prote ction technological development tendency will be: Computerizes, networked, protects, the control, the survey, the data comm unication integration and the artificial intellectualization.[ Key word ] relay protection present situation developme nt，relay protections future development1 relay protection development present situationThe electrical power system rapid development to the relay protection proposed unceasingly the new request, the electr onic 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 prot ection discipline, the relay protection design, the relay man ufacture industry and the relay protection technical team gro ws 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 tech nology , completed to have the deep relay protection theory attainments and the rich movement experience relay protectio n 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 establ ished our country relay manufacturing industry. Thus our coun try has completed the relay protection research, the design, the manufacture, the movement and the teaching complete sys tem in the 60's. This is a time which the mechanical and electrical relay protection prospers, was our country relay p rotection technology development has laid the solid foundation .From the end of the 50's, the transistor relay protectio n was starting to study. In the 60's to the 80's in arethe times which the transistor relay protection vigorous deve lopment and widely uses. Tianjin University and the Nanjing electric power automation plant cooperation research 500kv tra nsistor direction high frequency protection the transistor hig h frequency block system which develops with the Nanjing ele ctric power automation research institute is away from the p rotection, 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 operation al amplifier integrated circuit protection to study. Has form ed the complete series to at the end of 80's integrated ci rcuit protection,substitutes for the transistor protection grad ually. The development, the production, the application the i ntegrated circuit protects which to the beginning of the 90' s still were in the dominant position, this was the integrated circuit protection ti me. The integrated electricity road work frequency conversion quantity direction develops which in this aspect Nanjing el ectric power automation research institute high frequency prot ected the vital role , the Tianjin University and the Nanji ng electric power automation plant cooperation development int egrated circuit phase voltage compensated the type direction high frequency protection also moves in multi- strip 220kv a nd on the 500kv line.Our country namely started the computer relay protection research from the end of the 70's , the institutions of hi gher learning and the scientific research courtyard instituteforerunner's function. Huazhong University of Science and Te chnology, southeast the university, the North China electric power institute, the Xian Jiaotong University, the Tianjin Un iversity, Shanghai Jiaotong University, the Chongqing Universit y and the Nanjing electric power automation research institut e one after another has all developed the different principl e, the different pattern microcomputer protective device. In 1984 the original North China electric power institute develo ped the transmission line microcomputer protective device firs t through the appraisal, and in the system the find applica tion, 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 Univer sity of Science and Technology develops loses magnetism prote ction, the generator protection and the generator?Bank of tra nsformers protection also one after another in 1989, in 1994 through appraisal, investment movement. The Nanjing electric power automation research institute develops microcomputer li ne protective device also in 1991 through appraisal. The Tia njin University and the Nanjing electric power automation pla nt cooperation development microcomputer phase voltage compensa ted the type direction high frequency protection, the Xian J iaotong University and the Xu Chang relay factory cooperation development positive sequence breakdown component direction h igh 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 equipmen t protect unique, provided one batch of new generation ofperformance for the electrical power system fine, the funct ion has been complete, the work reliable relay protection in stallment. Along with the microcomputer protective device rese arch, 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 protect ed.2 relay protections future developmentThe relay protection technology future the tendency will be to computerizes, networked, the intellectualization, will p rotect, the control, the survey and the data communication i ntegration development. 2.1 computerizesAlong with the computer hardware swift and violent develo pment, the microcomputer protection hardware also unceasingly is developing. The original North China electric power instit ute develops the microcomputer line protection hardware has e xperienced 3 development phases: Ispublished from 8 lists cpu structure microcomputer prote ction, does not develop to 5 years time to the multi- cpu structure, latter developed to the main line does not leav e the module the big modular structure, the performance enha nces greatly, obtained the widespread application. Huazhong Un iversity 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 mic rocomputers protection.The Nanjing electric power automation research institute f rom the very beginning has developed 16 cpu is the foundati on microcomputer line protection, obtained the big area promo tion, at present also is studying 32 protections hardware sy stem. 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 c pu as the foundation microcomputer line protection, in 1988 namely started to study take 32 digital signals processor (d sp) as the foundation protection, the control, the survey in tegration microcomputer installment, at present cooperated with the Zhuhai Jin automatic equipment company develops one kin d of function complete 32 big modules, a module was a mini computer. Uses 32 microcomputers chips only to focus by no means on the precision, because of the precision the a/d sw itch 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 computat ion speed, very big addressing space, rich command system an d 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 integ rates the high speed buffer in cpu.The electrical power system the request which protects to the microcomputer enhances unceasingly, besides protection ba sic function, but also should have the large capacity breakdown information and the data long-term storage space, the fa st data processing function, the formidable traffic capacity, with other protections, the control device and dispatches t he networking by to share the entire system data, the infor mation and the network resources ability, the higher order l anguage programming and so on. This requests the microcompute r protective device to have is equal to a pc machine funct ion. In the computer protection development initial period, o nce conceived has made the relay protection installment with a minicomputer. At that time because the small machine vol ume big, the cost high, the reliability was bad, this tenta tive plan was not realistic. Now, with the microcomputer pro tective device size similar labor controlling machine function , the speed, the storage capacity greatly has surpassed the same year small machine, therefore, made the relay protecti on with complete set labor controlling machine the opportunit y already to be mature, this will be one of development di rections which the microcomputer protected. The Tianjin Univer sity has developed the relay protection installment which Che ng Yongtong microcomputer protective device structure quite sa me not less than one kind of labor controlling machine perf orms to change artificially becomes. This kind of equipment merit includes: has the 486pc machine complete function, ca n 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 cra ft excellent, quakeproof, guards against has been hot, guards against electronmagetic interference ability, may move in th e 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 irrever sible development tendency. How but to satisfies the electric al 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 sp ecifically the thorough research. 2.2 networkedThe computer network has become the information age as t he information and the data communication tool the technical prop, caused the human production and the social life appe arance has had the radical change. It profoundly is affectin g 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 associat ion protection, all relay protections installment all only ca n respond the protection installment place electricity spirit. The relay protection function also only is restricted in t he excision breakdown part, reduces the accident to affect t he scope. This mainly is because lacks the powerful data co mmunication method. Overseas already had proposed the system protection concept, this in mainly referred to the safe auto matic device at that time. Because the relay protection func tion not only is restricted in the excision breakdown part and the limit accident affects the scope (this is most impo rtant task), but also must guarantee the entire system thesecurity 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 th e superposition brake gear in analyze these information and in the data foundation the synchronized action, guarantees th e system the security stable movement. Obviously, realizes th is kind of system protection basic condition is joins the e ntire 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 realizat ion protective device computer networking also has the very big advantage. The relay protection equipment can obtain syst em failure information more, then to the breakdown nature, t he breakdown position judgment and the breakdown distance exa mination 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 i nformation, only then realization protection computer networked , can achieve this point.Regarding certain protective device realization computer ne tworkings, also can enhance the protection the reliability. T he Tianjin University in 1993 proposed in view of the futur e Three Gorges hydroelectric power station 500kv ultrahigh vo ltage multi- return routes generatrix one kind of distributional generatrix protection principle, developed successfully thi s kind of equipment initially. Its principle is disperses th e 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 v arious return routes protection screen, each protection unit joins with the computer network, each protection unit only i nputs this return route the amperage, after transforms it the digital quantity, transmits through the comput er network for other all return routes protection unit, each protection unit acts according to this return route the am perage and other all return routes amperage which obtains fr om the computer network, carries on the generatrix differenti al 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 gener atrix isolation. When generatrix area breakdown, each protecti on 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 rel iability compared to the traditional central generatrix protec tion principle. Because if a protection unit receives the di sturbance 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 exc ises, this regarding looks like the Three Gorges power plant to have the ultrahigh voltage generatrix the system key po sition 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 integrationsIn realization relay protection computerizing with under the condition, the protective device is in fact a high pe rformance, the multi-purpose computer, is in an entire electr ical power system computer network intelligent terminal. It m ay gain the electrical power system movement and breakdown a ny information and the data from the net, also may protect the part which obtains it any information and the data tr ansfer 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, th e 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, li ke the transformer, the line and so on the secondary voltag e, the electric current all must use the control cable to direct to . Lays the massive control cable not only must m assively invest, moreover makes the secondary circuit to be extremely complex. But if the above protection, the control, the survey, the data communication integration computer inst allation, will install in outdoor transformer substation by t。