機修廠機加工車間低壓配電系統(tǒng)及車間變電所設計外文翻譯

1、Power Supply and Distribution SystemThe basic function of the electric power system is to transport the electric power towards customers. The revolution of electric power system has brought a new big round construction, which is pushing the greater revolution of electric power technique along with t

2、he 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 an

3、d drives innovation of electric network. On the basis of national and internatio- nal advanced electric knowledge, the dissertation introduces the research hotspot for present electric power sy- etem as following.Firstly, this dissertation introduces the building condition of distribution automation

4、(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 et

5、c., 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-p

6、hase 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 thro

7、ugh 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

8、 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 stat

9、e 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 param

10、eter 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 b

11、een tested it's validity by example and made to be good practical effect.Power systemcontrol is very important issue to maintain the normal operation of a system.system voltage levels,frequency,tie-line flows,line currents,and equipment loading must be kept within limits determined to be safe in

12、 order to provide satisfactory service to the power system customers.Voltage levels, line currents, and equipment loading may vary from location within a system, and control is on a relatively local basis. For example, generator voltage is determined by the field current of each particular generatin

13、g unit; however, if the generator voltages are not coordinated,excess var flows result. Similarly, loading on individual generating units is determined by the throttle control on thermal units or the gate controls on hydro-units. each machine will respond individually to the energy input to its prim

14、e mover. Transmission line loadings are affected by power input from generating units and their loadings,the connected loads, parallel paths for power to flow on other lines, and their relative impedances.For satisfactory operation of a power system, the frequency should remain nearly constant. Rela

15、tiyely close control of frequency ensures constancy of speed of induction and synchronous motors.Constancy of speed of motor drives is particularly important for satisfactory performance of all the auxiliary drives associated with the fuel, the feed-water and -the combustion air supply system. In a

16、network, considerable drop in frequency could result in high magnetizing currents in induction motors and transformers. The extensive use of electric clocks and the use of frequency for other timing purpose require accurate maintenance of synchronous time which is proportional to integral. A change

17、in active power demand at one point is reflected throughout the system by a change in frequency. Because there are many generators supplying power into system, some means must be provided to allocate change in demand to the generators. A speed governor on each generating unit provides the primmy spe

18、ed control function, while supplementary control origination at a central control center allocates generation.In an interconnected system with two or more independently controlled areas, in addition to control of frequency, the generation within each area has to be controlled so as to maintain sched

19、uled power interchange. The control of generation and frequency is commonly referred to as load-frequency control (LFC.The control measures of power and frequency include:(1 Regulation of the generator speed governor(2 Underfrequency load shedding(3 Automatic generation control (AGCAGC is an effecti

20、ve means for power frequency control in large-scale power systems. In an Interconnected power system, the primary objectives of AGC are to regulate frequency to the specified nominal value and to maintain the interchange power between control area at the scheduled values by adjust the output of the

21、selected generators. This function is commonly referred to as load-frequency control. A secondary objective is to distribute the required change in generation omong units to minimize operating costs.For efficient and reliable operation of power system, the control of voltage and reactive power shoul

22、d satisfy the following objectives:(1 Voltages at the terminals of all equipment in the system are within acceptable limits. Both utility equipment and customer equipment are designed to operate at a certain voltage rating. Prolonged operation of the equipment at voltages outside the allowable rang

23、could adversely affect their performance and possibly cause them damage.(2 System stability is enhanced to maximize utilization of the transmission system.(3 The reactive power flow is minimzed as to reduce the equipment and the transmission lines losses to a practical minimum. This ensures that the

24、 transmission system operates efficiently,i.e. mainly for active power transfer.The problem of maintaining, voltages within the required limits is complicated by the fact that the Power system supplies power to a vast number of loads and is fed from many generating units. As 1oads vary, the reactive

25、 power requirements of the transmission system vary. Sincereactive power cannott be transmitted over long distance, voltage control has to be effected by using special devices dispersed throughout the system. This is in contrast to the control of frequency which depends on overall system active powe

26、r balance. The proper selection and coordination of equipment for controlling reactive power and voltage are among the major challenges of power system engineering.The control of voltage levels is accomplished by controlling the production, absorption, and flow of reactive power at all levels in the

27、 system. The generating units provide the basic neans of voltage control; the automatic voltage regulators control field excitation to maintain a scheduled voltage level at the terminals of the generators. Additional means are usually required to control voltage throughout the ststem. The devices us

28、ed for this purpose may be classified as follows:(1 Sources of reactive power, such as series capars, shunt reactors, synchro-nous condensers, and static var compensators (SVCs.(2 Line reactance compensators, such as series capacitors.(3 Regulating transformers, such as tap-changing tarsformers and

29、boosters.Synchronous condensers and SVCs provide active compensation;the reactive power absorbed/supplied by them is automatically adjust so as to maintain voltages of the buses to which they are connected.供配電系統(tǒng)電力系統(tǒng)的基本功能是向用戶輸送電能。電力體制的改革引發(fā)了新一輪大規(guī)模的電力建設熱潮,從而極大地推動了電力技術革命。新技術新設備的開發(fā)與應用日新月異特別是信息技術與電力技術的結合在

30、很大程度上提高了電能質量和電力供應的可靠性。由于技術的發(fā)展,又降低了電力建設的成本,進而推動了電網設備的更新?lián)Q代。本文就是以此為契機以國內外配電自動化中一些前沿問題為內容,以配電自動化建設為背景,對當前電力系統(tǒng)的熱點技術進行一些較深入的探討和研究,主要完成了如下工作。(1提出了配電自動化建設的兩個典型模式即,體化模式和分立化模式。側重分析了分立模式下的配電自動化系統(tǒng)體系結構,給出了軟硬件配置主站選擇管理模式最佳通訊方式等是本文研究的前提和實現(xiàn)平臺。(2針對配電自動化中故障測量定位與隔離以及供電恢復這一關鍵問題,分析了線路故障中電壓電流等電量的變化,導出了相間短路工況下故障定位的數(shù)學描述方程,并

31、給出了方程的解以及故障情況下幾個重要參數(shù)s U& s I& e I& 。選擇表通過對故障的自動診斷與分析得出了優(yōu)化的隔離和恢復供電方案。自動實現(xiàn)故障快速隔離與網絡重構,減少了用戶停電范圍和時間,有效提高配網供電可靠性。文中還給出了故障分段判斷以及網絡快速重構的軟件流程和使用方法。(3狀態(tài)估計是實現(xiàn)配電自動化中關鍵技術之一。本文在闡述狀態(tài)估計方法基礎上給出了不良測量數(shù)據(jù)的識別和結構性錯誤的識別方法,針對狀態(tài)估計中數(shù)據(jù)對基于殘差的壞數(shù)據(jù)檢測和異常以及狀態(tài)量中壞數(shù)據(jù)對狀態(tài)估計的影響及存在的問題,提出了狀態(tài)估計中拓撲錯誤的一種實用化檢測和辯識方法針對竊電漏計電費問題獨創(chuàng)性。提出

32、一種通過電量突變和異常分析防止竊電的新方法,并在濰坊城區(qū)配電得到驗證。(4針對配電網負荷預測建模困難參數(shù)離散度大以及相關因素多等問題。本文在分析常規(guī)負荷預測模型及方法基礎上引入了氣象因素日期類型社會環(huán)境影響等,參數(shù)給出了基于神經網絡的電力負荷預測方法實例驗證了方法的正確性。電力系統(tǒng)控制是維持電力系統(tǒng)正常運行非常重要的問題。為了給電力系統(tǒng)的用戶提供令人滿意的服務,系統(tǒng)的電壓、頻率、連接線處的涌流、線電流,以及設備負荷率,必須要限制在安全的范圍之內。系統(tǒng)中的電壓、線電流和設備負荷率在各處的情形可能是不相同的,會因所處的位置而異。因而,電力系統(tǒng)的控制也就應該因地制宜。比如說,發(fā)電機的電壓由各自的發(fā)電

33、機組的勵磁電流所決定。然而,如果某臺發(fā)電機電壓因為勵磁電流的問題而與系統(tǒng)的電壓有所差棄今便會在系統(tǒng)中另外產生無功潮流。同樣,每臺機組的負荷,在汽輪發(fā)電機組中是一由燕汽閥門控制決定的,在水輪發(fā)電機組中是由水流閘門控制決定的。每一臺機組都要分別對來合于其原動機的能量輸人做出反應。輸電線的負荷情況,受到發(fā)電機組及其負載、連接的負荷、與乏棄準時其他線路上的涌流,以及其相關的阻抗的影響。為能使電力系統(tǒng)的運行得到令人滿意的效果,頻率應該維持大致恒定。頻率的相關控制確保了電磁感應電動機和同步電動機轉速的恒定。電動機轉速的恒定對于那些與像燃料、給水和燃燒系的送風等,有關的輔助設備的良好運行來說是尤其重要的。在電網中.當頻率下降到一定程度,就會引起感應電動機和變壓器中激磁電流增大。電鐘和其他運川頻率計時的裝置的廣泛應用,都要求維持準確的同步時間,而時間是與頻率的積分成正比的。系統(tǒng)中某一處的有功功率需求的變化,是系統(tǒng)頻率變化的反應。因為系統(tǒng)中有許多臺發(fā)電機在向電網提供有功功率.所以必須將這些變化按照需求分別分配到各臺發(fā)電機。每臺發(fā)電機組的