無功規(guī)劃及其在功率管理中的運(yùn)行畢業(yè)論文外文翻譯

1、reactive power planningand operating in the deregulated power utilities. introductionthe purposes of this paper are to review the current strategy of reactive power management and search for proper reactive power strategy, which is expected to result in a more efficient and economic way in reactive

2、power management. these goals are actually consistent with the spirit of the deregulation of power industry. reactive power affects system voltages, energy loss as well as system security. as power system deregulation has been widely accepted by power industry, the philosophy of reactive power manag

3、ement and power system operation is expected to be much different in order to meet the spirit of deregulation and the security requirements. in a vertically integrated utility, reactive power facilities are owned and operated by the same utility. the costs and contribution of reactive power supply a

4、re not precisely evaluated. under deregulation circumstance, the obligations and rights of the owners of reactive power facilities become an essential issue that affects not only the investment returns of power industry but also the power system security. this situation is even more complicated for

5、the interconnection of several self-supported systems.reactive power is always required during power delivery in an ac system even there are no reactive power loads. however, unlike real power, reactive power is not consumed by any elements of a power system. reactive power is swapping twice per vol

6、tage cycle between capacitive elements and inductive elements. when capacitive elements are absorbing reactive power, inductive elements must be releasing reactive power, and vise versa. the capacities of these capacitive/inductive elements are not always constant. the amount of reactive power that

7、is related to line charging is proportional, while that related to series reactance is proportional.reactive power compensation can be made at different levels: distribution, transmission and generation. for a vertically integrated utility, the costs of reactive power compensation might be included

8、into distribution cost or transmission cost depending on where the compensation devices are installed. the costs of reactive power supplied by generators might not be listed separately, or even the reactive power capacities of generators are not considered as the costs of reactive power. when utilit

9、ies are doing reactive power planning, different utilities might have different considerations. no matter how utilities treat the costs of reactive power compensation or how they carry out the planning, the electricity price always reflects this part of costs. in the deregulated power industry, seve

10、ral questions that were not seriously discussed in regulated era are raised, such as: who is responsible for the reactive power compensation, are the providers of reactive power services, do consumers need to pay for the required reactive power loads, what roles should generation companies play in r

11、eactive power compensation, etc.under deregulation circumstance, power system security faces more threats than ever. due to the potential dynamic power trading, the reactive power requirements are also dynamically changing. some generation units are inefficient in generating real power and are not c

12、ompetitive on power market. however, they are necessary to stay online in order to maintain system voltage. this type of must-run units causes few arguments in the regulated power industry. not all must-run units must be on-line all the time. depending load and operating conditions, some of them can

13、 be off-line but must be standby and some of them must be on-line only under certain conditions. most generators have a limitation of minimum real power output and can not simply operate as synchronous condensers. their operating costs should include real power cost.reactive power compensation atdis

14、tribution levelmain purposes of reactive power compensation at load sites are to reduce long distance transmission of reactive power and reduce the reactive power flow within distribution network, thus reduce mw loss and voltage dip. reactive power itself is sort of energy swapping between reactive

15、element and capacitive element and is not consumed for pure reactive and capacitive elements. if most of reactive power load can be supplied at load sites, the amount of reactive power flow in either transmission network or distribution network can be reduced.fig. 1 is a 12-bus sample system which i

16、s a small piece of distribution network of new york city. the loads and shunt compensations shown in the figure are three phase total. balanced three-phase load is assumed in the calculation. four compensation cases are presented to illustrate the effects on mw loss and voltage dip. all four cases a

17、re under same load conditions as shown in fig. 1 except that the reactive power compensations are different:case 1 : without reactive power compensation.case 2: reactive power compensations are shown in fig. 1.case 3: total reactive power compensation of case 2(1380 kvar) is made at bus # 1case4: re

18、active power compensation at bus #1 is increased to obtain unity power factor.similar situation can be found from bus voltages. compensation method of case 2 is most effective in voltage improvement among those cases. case 3 and case 4 have no direct effects on bus voltages of distribution network.r

19、eactive power compensation in transmission networkfor normal operation the compensation should be sufficient to keep the voltages of feeders within an acceptable range. for emergency operation the compensation should be able to keep the voltages within a wider acceptable range with the reactive powe

20、r support from generation companies.fig. 2 is a small system of 110 buses, 136 branches including 71 transformers and 33 generators. system load is about 400 mw. individual bus loads are not shown in the figure. the first case is base case. in the base case power factors of generators are not necess

21、ary the same and, similarly, power factors of load buses are not necessary the same either. in the second case, load conditions are the same as base case, including 3 shunt compensations, but with the generators operating near unity power factor. the last four cases, generators are operating near un

22、ity power factor and the power factor of all load buses is assumed 1.0, 0.95, 0.9 and 0.85, respectively.reactive power resreve of generatorsthe proposed reactive power management scheme assumes that generators are not responsible for reactive power supply under normal operation conditions. the gene

23、rators, however, have to have sufficient reactive power reserve for contingencies. an important issue is how much reserve is necessary for each generator since reactive power capacity directly affects generator price. properties of contingency, location of power plant and criteria of voltage quality

24、 all affect the required amount of reactive power reserve for the generators. for the interconnected system, the strength of tie lines and neighboring systems also play an essential role. it is different from the estimation of real power spinning reserve, power plant outage is not necessary severer

25、than reactive power facility failure. therefore the reactive power reserve for contingency for each generator should be carefully defined.conclusionsthis paper suggests that the distribution companies are responsible for the compensation of reactive power loads and the transmission companies are res

26、ponsible for the necessary reactive power compensation to ensure the power delivery under normal conditions. the generation companies are responsible for reactive power requirements under contingency conditions. transmission companies are entitled to charge to distribution companies for supplying re

27、active power load if the distribution companies are unable to keep unity power factor. generation companies are entitled to charge the transmission companies for the reactive power supplies during normal operation. the generators should keep certain amounts of reactive power reserve for contingencie

28、s. 英文文獻(xiàn)譯文無功規(guī)劃及其在功率管理中的運(yùn)行、緒論這篇論文的目的是評論無功管理的發(fā)展策略和尋找一個(gè)更適當(dāng)?shù)臒o功策略，即期望其在無功管理中更有效更經(jīng)濟(jì)的方法。這些目標(biāo)事實(shí)上是和電力工業(yè)異常時(shí)的精神是一致的。無功功率影響系統(tǒng)的電壓、能量損耗及系統(tǒng)安全。隨著電力系統(tǒng)違規(guī)規(guī)則被廣泛接受，為了會合規(guī)則的精神和安全需求，電力系統(tǒng)管理和電力系統(tǒng)運(yùn)行方面的專家被寄予不同的期望。在一個(gè)垂直的、完整的效用體系中，無功設(shè)備通過相同的效用承認(rèn)和運(yùn)行。無功補(bǔ)償?shù)拇鷥r(jià)和貢獻(xiàn)并不是實(shí)際的估值。在違規(guī)條件下，無功設(shè)備所有者的權(quán)利和職責(zé)成為本質(zhì)的事件，不僅影響電力工業(yè)的投資回報(bào)還影響電力系統(tǒng)的安全。這種情形在幾個(gè)自給的互相

29、聯(lián)絡(luò)的系統(tǒng)中甚至更復(fù)雜。無功功率在一個(gè)甚至沒有無功負(fù)載的交流系統(tǒng)的功率傳輸中也是必需的，不像有功，無功不被電力系統(tǒng)中的任何一個(gè)元件消耗。無功在容性元件和感性元件之間每一電壓周期交換兩次。當(dāng)容性元件吸收無功，則感性元件必須發(fā)出無功，而且數(shù)值相同。這些容性/感性元件的容量并不常常是不變的。線性負(fù)荷無功的量是均衡的，相關(guān)的連續(xù)電抗也是均衡的。無功補(bǔ)償可以被調(diào)整在不同的標(biāo)準(zhǔn)：分配、傳輸、產(chǎn)生。作為一個(gè)垂直的完整的設(shè)備，無功補(bǔ)償器的成本或許包括在配電成本中或者在輸電成本中取決于補(bǔ)償設(shè)備的安裝位置。發(fā)電機(jī)無功補(bǔ)償?shù)墓┙o成本可能不被分離列出，或者甚至發(fā)電機(jī)的無功能量作為無功成本不被考慮。當(dāng)設(shè)備作為無功規(guī)劃，

30、不同的設(shè)備可能有不同的考慮。不管無功補(bǔ)償?shù)某杀驹鯓?，他們怎樣編制?jì)劃，電費(fèi)始終反映這部分費(fèi)用。在電力工業(yè)中，有幾個(gè)不嚴(yán)重的在控制時(shí)代被討論的問題被提出，像：誰負(fù)責(zé)無功功率的補(bǔ)償？是無功補(bǔ)償裝置提供，消費(fèi)者是否需要支付無功負(fù)載的費(fèi)用？發(fā)電機(jī)應(yīng)該在無功功率補(bǔ)償中擔(dān)當(dāng)什么角色？等等。在違規(guī)情況下，電力系統(tǒng)安全比以前面臨更多的威脅。由于電力潛在的動態(tài)交換，無功需求也是動態(tài)變化的。一些發(fā)電廠發(fā)出有功效率低下及在電力市場不具有競爭力。但是它們?yōu)榱思訌?qiáng)系統(tǒng)電壓保持上電網(wǎng)是必要的。這種必須運(yùn)行的電廠在被管制的電力工業(yè)引起一些爭議。依據(jù)負(fù)荷和運(yùn)行條件，它們中的一些可以不用上網(wǎng)但是必須作為后備，另一些僅在確定的條件下必須上網(wǎng)。大部分發(fā)電機(jī)有實(shí)際最小視在功率輸出的限制，并且不能簡單地作為同步電容器運(yùn)轉(zhuǎn)。它們的運(yùn)行費(fèi)用應(yīng)該包含視在功率成本。ii、配電網(wǎng)絡(luò)中的無功補(bǔ)償 負(fù)載點(diǎn)無功補(bǔ)償?shù)闹饕康氖菧p小長距離輸電的無功功率和減少配電網(wǎng)絡(luò)的