【正文】 hence transformer equipment is included.Sectionalizing.─In very long highvoltage large capacity lines, particularly when several circuits are run in parallel, it is often necessary to split the lines into sections, in order that proper protection to the line and service can be obtained. Such a substation is , therefore, helpful in sectionalizing damaged sections of a line, providing continuity of service. Such a substation will generally prise only switching equipment. In long lines it may also serve to supply powerfactorcorrecting equipment.Transmissionline Supply.─It is being more and more mon to install the hightension equipment of a power plant outdoors, the installation being nothing more than a stepup substation receiving its power at generator voltage, then stepping up its voltage and finally sending it out over highvoltage transmission lines. Such a substation is nothing more than an outdoor distributing substation turned around, the voltage being stepped up instead of stepped down.Powerfactor Correction.─The voltage at the end of long lines tends to increase as the load supplied is decreased, while on the other hand it tends to decrease as the load is increased. Owing to the inductance and capacity effects, this variation in voltage is acpanied by a wide variation in power factor of a line, it is necessary to use synchronous condensers at the end of the line. To supply such a machine the transmissionline voltage must be stepped down, hence a powerfactorcorrecting substation will include switching equipment, transformers, and all equipment necessary for the operation of synchronous condensers.Railway.─Substations supplying railways may be generally classified under two heads, namely, as alternating current and as direct current. In the cases of alternatingcurrent substations the problem is generally one of voltage transformation and of supplying singlephase power to the trains. It is, however, possible to supply singlephase to threephase inside the lootive by the use of a phase converter. In the case of directcurrent railways, the substations are generally supplied whit threephase power and converted to direct current by means of rotary converters, motorgenerator sets, or rectifiers.Direct current for Light and Power.─There are still a few sections in some of out large cities, which are supplied with directcurrent threewire systems. Such a supply is invariably obtained from synchronous converters. There are also certain types of motor loads in industrial plants, which require direct current.Because many cities have experience rapid growth, their substations have often reached the limits of their capacity. As a result, downtown distribution systems are often overworked and many need a major, overhaul, overhaul, or expansion. However, space is scarce. Downtown business owners do not want “ugly” new substation marring the area’s appearance, but nor do businesses and residents grid the prospect of grid disturbances.One example of a system capable of integrating equipment monitoring with substation automation is the GE Harris integrated Substation Control System (ISCS). The system can integrate data from both substation system and equipment online monitoring devices into a mon data base. The data can then be processed by an expert system into information on the status and health of monitored equipment using selfdiagnostic programs. This information is then sent to a CMMS for automatic generation and tracking of maintenance work orders leads directly to the significant efficiencies found with conditionbased maintenance programs.ABB Power and its industry partners have bined to develop the ABB Power System software. The system contains a diagnostic and maintenance system that reports necessary maintenance before failure. It allows utilities and industrial customers to easily expand from a single puter to a full system, without reengineering.the directional protection basisEarly attempts to improve powerservice reliability to loads remote from generation led to the dualline concept. Of course, it is possible to build two lines to a load, and switch the load to whichever line remains energized after a disturbance. But better service continuity will be available if both lines normally feed the load and only the faulted line is tripped when disturbances occur. shows a singlegenerator, twoline, singleload system with breakers properly arranged to supply the load when one line is faulted. For the arrangement to be effective it is necessary to have the proper relay application. Otherwise, the expensive power equipment will not be able to perform as planned. Consider the application of instantaneous and/or time delay relays on the four breakers. Obviously the type of the relay cannot coordinate for all line faults. For example, a fault on the line terminals of breaker D. D tripping should be faster than B, however, the condition reverses and B should be faster than D. It is evident that the relay protection engineer must find some characteristic other than time delay if relay coordination is to be achieved.The magnitude of the fault current through breakers B and D is the。[3] ［S］.北京:景老師細心、全面的審閱了全文，并提出了許多寶貴意見，對提高論文的水平和研究方向上的把握起到了重要的作用。我在完成論文期間得到了景老師的精心指導(dǎo)和熱情幫助，為我們提供了良好的學(xué)習(xí)環(huán)境和不可多得的鍛煉機會。同時，也感謝在此次畢業(yè)設(shè)計中給予我?guī)椭乃腥?。?dāng)然在保護配置方面，我自己認為還是存在許多的不足之處，如：在保護配置方面，為了保證基本要求，應(yīng)該加裝自動裝置；對于線路方面的保護配置，我認為還應(yīng)該進一步的細化；對于電纜的選擇，我認為還是有點模糊，有些東西還是理解不太深刻。在這個設(shè)計中,我主要做了關(guān)于35kV變電站的相關(guān)保護,從負荷計算到主接線的選擇；從短路電流計算到導(dǎo)線電纜的選擇、校驗；從主變壓器繼電保護的配置到線路繼電保護的計算、校驗。 當(dāng)然這次的設(shè)計還有一些上述不足之處，需要我不斷的去學(xué)習(xí)，去改進。這次畢業(yè)設(shè)計由于資料不夠，所以我們多人一組共享資源，這無意是對我們的相互協(xié)作能力的考驗，在遇到一個人不能解決的問題時，我們共同商量，找到解決的方法。當(dāng)對繼電保護知識有了一定的了解后，指導(dǎo)老師景展及時給我們作了指導(dǎo)，使我們對畢業(yè)設(shè)計的任務(wù)及著手點有了明確的認識，自己的頭腦中也形成了此次畢業(yè)設(shè)計課題的一個大概框架?？梢哉f，收獲還是挺大的。其中：；2) 保護的動作時限t2應(yīng)與t1配合，即： （），故選用DS111型時間繼電器，～ s。其中：；2) 保護的動作時限t2應(yīng)與t1配合，即： （），故選用DS111型時間繼電器，～ s。3)由于其動作時間為0s，為防止其在線路上管型避雷器放電時誤動，~。式中 ——系統(tǒng)最大運