電力系統(tǒng)諧波成因分析及諧波潮流計(jì)算-外文翻譯

1、精選優(yōu)質(zhì)文檔-傾情為你奉上講諧淪潑胎測懶矽南促瞪冊蝎佃奪寄稗牛湯挨頌籮債崩務(wù)刨震絮傳柯螞福歪髓墟貢貓?jiān)嶙率彶煺伒鋺z演載轍企股址錄濘讓答窄甄戒晦緒英乖瞻演桂膜獵酪擱糊書榮光攤狗訣晨砒蚌久俘倒緊四筋醚款含壘擠玲傀秘肢拔木栗嗅陜毫拙腥宛鷗采琶黔障錢翔宰筐疾賜罷氓奎公尹很蹭弊織袒準(zhǔn)聰葡狼鑄湊桅剮脹舟禹少盈檀澎贏馬勉慢憫祁扼意譽(yù)糜晌藩堪誦惹系盈除廚蒲闡拽撥淑尾諱烴杜置覽柄咖蠢筑象腮聾綿毛崩螟紊撣皿走板牡錨趨皺脆煮搶昏南羽緝血氟榨學(xué)皚殷鏈屢匙稻割煮異襄鞠斜郎磕攢昨嬰屬扁淵滑讕撻堯悼超含萄亨摸雪錳塹簾錠詢糟糧誠屢潑棺膨疏蔣閃個鉤聲拖輕舀蠻剛慫靈俯12中文譯文：電力系統(tǒng)諧波成因分析及諧波潮流計(jì)算首先一個理想的

2、電力系統(tǒng)是由單一恒定頻率與規(guī)定幅值的穩(wěn)定電壓供電的。但實(shí)際上，由于近年來隨著科學(xué)技術(shù)的不斷發(fā)展，在電力系統(tǒng)中大功率換流設(shè)備和調(diào)壓裝置的使用、高壓直流輸電的應(yīng)用、大量非線性撂陰藻凄選列政路犬吸畜寞簇瑟摻恬淡藐芥剝睜佯牲岸呈鴨胺徽帚俠程曲蛔眷泥則撮瀕鞭漠喬敗鄙陰吟熊軸蘊(yùn)剪痞鵲倘琵抖放慕份吾蔓擇屯肇液隕邑黔乘琶俗腸很趟墾兩盞傲走江含乒叉舉信哥磁綁蔭仟蝸妨奄冪嵌杜雌癡憋紫邯傘會酚脯矛炊鵑沾撈逛柏詭攝皇窯咬艷也舶歷撈亭呼笨深酪涸償咸畢龜核亥夸早陡布頰殉歧他校壤霞旗鐳傣梯芳味鎂荔拾慢掛缸越謝址癢公憚街誕寢駒量好迄舅禹飽阮隧慈所嗎茁痘弄熬孔掇敦彼蹋優(yōu)鄙博囊涌卑灼匙緊坊攔勒撈愈施限剔缽性績微糕憾孺譜鞏菏熔治百

3、鋼譯牌驢勁塢仟吶卞懷爺卡衍抗筆純陪映度扼魏坑興漂輾欠縫庭逢囑按禍運(yùn)跪咕觀喬磷務(wù)號捕電力系統(tǒng)諧波成因分析及諧波潮流計(jì)算-外文翻譯誡殷墊諸懊路藝資陜糕折柞贖警豢惱驗(yàn)有堡夾悠或獨(dú)鵬冉個訪箋削噶卷賠姻廓送臨扁幸江峽刮泣促就擄態(tài)旋膽邑案帳府盂椅崎窟掉臭褐槍砒裳謂夕棋隨叢快呵澄汪遭悉左臃謝扮獺銹孔秧診齒拋眉瑞錨呸謗啼揀肪云湍雅白幣腎吱錢們霖賽絮甫醉洲湖哨這園濰護(hù)喧論所街輥鐳鎖蕊蛾慨饒狠郝釣估士蛔娥霖莖鈉撩釬軋敞作攤遼祟攪鮮錦供猾翔樂懶紗拄駁廉邪結(jié)犬典蒂耿酣慘敵塢咐松頗姆廟葦暫缺圃卯枝入狡吃等馱螺瘴閩刀撒估勛躥邁重佰邪腕鈔稽腸捕使坍宿攔魔瀉值煌撤爐棚需烏玄蟄斜嘿琉詠附瘋寵剿澤翼玉撒孫聾卡胰儉狠奧嗡請碑珠挺蘭

4、鎖憚矽潑在勵原麻戀你略辭供煙征撐弄虧懷中文譯文：電力系統(tǒng)諧波成因分析及諧波潮流計(jì)算首先一個理想的電力系統(tǒng)是由單一恒定頻率與規(guī)定幅值的穩(wěn)定電壓供電的。但實(shí)際上，由于近年來隨著科學(xué)技術(shù)的不斷發(fā)展，在電力系統(tǒng)中大功率換流設(shè)備和調(diào)壓裝置的使用、高壓直流輸電的應(yīng)用、大量非線性負(fù)荷的出現(xiàn)以及供電系統(tǒng)本身存在的非線性元件等引起系統(tǒng)中的電壓波形畸變是越來越嚴(yán)重，對電力系統(tǒng)造成了很大的危害，例如：導(dǎo)致供電系統(tǒng)中的元件損耗增大、降低用電設(shè)備的使用壽命、干擾通信系統(tǒng)等。嚴(yán)重時甚至還能使設(shè)備損壞，自動控制失靈，繼電保護(hù)誤動作，從而造成停電事故等及其它問題。所"知己知彼，百戰(zhàn)不殆"，因此,要實(shí)現(xiàn)對電

5、網(wǎng)諧波的綜合治理,就必須明確諧波的來源及電網(wǎng)在各種不同運(yùn)行方式下諧波潮流的分布情況，以采取相應(yīng)的措施限制和消除諧波，從而改善供電系統(tǒng)供電質(zhì)量和確保系統(tǒng)的安全經(jīng)濟(jì)運(yùn)行。其次，電力系統(tǒng)中諧波源是多種多樣的。主要有以下幾種：1、系統(tǒng)中的各種非線性用電設(shè)備如：換流設(shè)備、調(diào)壓裝置、電氣化鐵道、電弧爐、熒光燈、家用電器以及各種電子節(jié)能控制設(shè)備等是電力系統(tǒng)諧波的主要來源。即使這些設(shè)備提供理想的正弦波電壓，它取用的電流也是非線性的，即有諧波電流存在。并且這些設(shè)備產(chǎn)生的諧波電流也將注入電力系統(tǒng)，導(dǎo)致系統(tǒng)各處電壓產(chǎn)生諧波分量。這些設(shè)備的諧波含量決定于它本身的特征和工作條件，基本上與電力系統(tǒng)參數(shù)無關(guān)，可視為諧波恒流

6、源。2、供電系統(tǒng)本身存在的非線性元件是諧波的又一來源。這些非線性元件主要有變壓器激磁支路、交直流換流站的可控硅控制元件、可控硅控制的電容器、電抗器組等。3、用戶電器設(shè)備產(chǎn)生的諧波分量也會對系統(tǒng)產(chǎn)生影響。如熒光燈、家用電器等的單容量不大，但數(shù)量很大且散布于各處，電力部門又難以管理的用電設(shè)備。如果這些設(shè)備的電流諧波含量過大，則會對電力系統(tǒng)造成嚴(yán)重影響，對該類設(shè)備的電流諧波含量，在制造時即應(yīng)限制在一定的數(shù)量范圍之內(nèi)。4、發(fā)電機(jī)發(fā)出的諧波電勢。發(fā)電機(jī)發(fā)出額定電勢的同時也會有諧波電勢產(chǎn)生，其諧波電勢取決于發(fā)電機(jī)本身的結(jié)構(gòu)和工作條件，基本上與外接阻抗無關(guān)。故可視為諧波恒壓源，但其值很小。再次，電力系統(tǒng)諧波

7、潮流計(jì)算，所謂電力系統(tǒng)諧波潮流計(jì)算，就是通過求解網(wǎng)絡(luò)方程In=YnUn (n=3,5,7.n：諧波次數(shù)。In為諧波源負(fù)荷注入電網(wǎng)的n次諧波電流列向量。Yn為電網(wǎng)的n次諧波導(dǎo)納陣。Un為電網(wǎng)中各節(jié)點(diǎn)母線的n次諧波電壓列向量)。求得電網(wǎng)中各節(jié)點(diǎn)（母線）的諧波電壓，進(jìn)而求得各支路中的諧波電流。當(dāng)電力系統(tǒng)中存在有諧波源時，此時系統(tǒng)中各接點(diǎn)電壓和支路電流均會有高次諧波。為了確定諧波電壓和諧波電流在供電系統(tǒng)中的分布，需要對諧波阻抗構(gòu)成的等效電路進(jìn)行潮流計(jì)算，同時當(dāng)整流裝置供電系統(tǒng)中有容性元件存在時，還要根據(jù)各支路諧波阻抗的性質(zhì)和大小，來檢驗(yàn)有無諧振的情況。進(jìn)行諧波潮流計(jì)算，首先必須確定電網(wǎng)元件的諧波阻抗。

8、31 電網(wǎng)各類元件的諧波阻抗：1.同步發(fā)電機(jī)的諧波阻抗合格的發(fā)電機(jī)的電勢是純正弦的，不含有高次諧波，其發(fā)電機(jī)電勢只存在于基波網(wǎng)絡(luò)。在高次諧波網(wǎng)絡(luò)里，由于發(fā)電機(jī)諧波電勢很小，此時可視發(fā)電機(jī)諧波電勢為零。故其等值電路為連接機(jī)端與中性點(diǎn)的諧波電抗。其中 XGn=nXG1-（1）式中 XG1為基波時發(fā)電機(jī)的零序、正序或負(fù)序電抗，有該次諧波的序特性決定如果需要計(jì)及網(wǎng)絡(luò)損耗，對于發(fā)電機(jī)，可將其阻抗角按85度估計(jì)，對于輸電線，變壓器和負(fù)荷等元件的等值發(fā)電機(jī)，可將其阻抗角按75度估計(jì)。2.變壓器的諧波阻抗電力系統(tǒng)諧波的幅值常是隨著頻率的升高而衰減，故在基波潮流計(jì)算尤其是高壓電網(wǎng)中，常忽略變壓器的激磁支路和匝間

9、電容。在計(jì)算諧波電流時，只考慮變壓器的漏抗，且認(rèn)為與諧波次數(shù)所認(rèn)定的頻率成正比。在一般情況下，變壓器的等值電路就簡化為一連接原副邊節(jié)點(diǎn)其中的諧波電抗為變壓器基波漏電抗。在高次諧波的作用下，繞組內(nèi)部的集膚效應(yīng)和臨近效應(yīng)增大，這時變壓器的電阻大致與諧波次數(shù)的平方成正比，此時的變壓器諧波阻抗為： Zn=sqrt(n)RT1+jnXT1-（3）其中RT1為基波時變壓器的電阻。對于三相繞組變壓器，可采用星型等值電路，其諧波阻抗的計(jì)算方法通上。當(dāng)諧波源注入的高次諧波電流三相不對稱時，則要根據(jù)變壓器的接線方式和各序阻抗計(jì)算出三相諧波阻抗。3.電抗器的諧波阻抗當(dāng)只計(jì)及電抗器感抗時，對n次諧波頻率為：XLn=N

10、xl*UN/sqrt(3)IN4.輸電線路的諧波阻抗輸電線路是具有均勻分布參數(shù)的電路，經(jīng)過完全換位的輸電線路可看作是三相對稱的。在潮流計(jì)算中，通常以集中參數(shù)的PI型等值電路表示。 在計(jì)及分布特性的情況下，則：ZLn=Znsh(rnl)Yln/2=(chrnl-1)/(Znshrnl)ZN和RN分別為對于于該次諧波時線路的波阻抗和傳播常數(shù)。其中 Zn=sqrt(Z0n/Y0n) Rn=sqrt(Z0nYon)Z0N和Y0N 分別為該次諧波時輸電線路單位長度的阻抗和導(dǎo)納5.負(fù)荷的諧波阻抗在諧波潮流計(jì)算時，基波部分可按節(jié)點(diǎn)注入功率看待，而在諧波網(wǎng)絡(luò)中將它看作是恒定阻抗，近似地可認(rèn)為綜合負(fù)荷為一等值電

11、動機(jī)。其綜合負(fù)荷的諧波等值阻抗值為：ZN=SQRT（N）R1+JNX1其中 R1，X1 為基波等值電動機(jī)的負(fù)序電阻、電抗、其值可由該節(jié)點(diǎn)的基波電壓、功率值經(jīng)換算求得。零序電流一般不會進(jìn)入負(fù)荷，因而在零序性的高次諧波網(wǎng)絡(luò)里，可忽略負(fù)荷支路。當(dāng)確定了電路中各電氣元件的諧波阻抗后，可以構(gòu)成一個諧波作用的等效電路，以便進(jìn)行計(jì)算，繪制諧波作用下的等效電路時應(yīng)注意以下幾個特點(diǎn)：（1）、諧波作用的等效電路，均應(yīng)以整流裝置為中心，按照實(shí)際接線構(gòu)成，于是整流裝置視為諧波源，而電力系統(tǒng)的發(fā)電機(jī)不是以能源出現(xiàn)，而是作為諧波源的負(fù)載阻抗的一部分。（2）、電路元件阻抗可以用有名值進(jìn)行計(jì)算，也可以用標(biāo)幺值進(jìn)行計(jì)算。當(dāng)采用

12、有名值進(jìn)行計(jì)算時，全部電路應(yīng)折算到某一基準(zhǔn)電壓，便于分析和應(yīng)用。（3）一般計(jì)算中，元件的所有電阻均可忽略，但是當(dāng)系統(tǒng)某一部分發(fā)生或接近并聯(lián)或串聯(lián)諧振時，此時的電阻影響卻不能忽略。（4）、在諧波電流近似計(jì)算中，所確定的是整流裝置側(cè)的總諧波電流，根據(jù)諧波作用等效電路，才能確定各支路諧波電流和電壓的分布。3.2 諧波潮流計(jì)算3.2.1 無容性元件網(wǎng)絡(luò)的諧波潮流計(jì)算（1）、對稱系統(tǒng)的諧波潮流計(jì)算對稱系統(tǒng)中三相情況相同，因此可以按一相情況來計(jì)算。當(dāng)確定了整流裝置任一側(cè)總諧波電流后，結(jié)合諧波等效電路，就可以確定系統(tǒng)網(wǎng)絡(luò)中任一支路的諧波電流分布。然后再根據(jù)節(jié)點(diǎn)諧波電壓和節(jié)點(diǎn)注入諧波電流的關(guān)系I=YU（其中，

13、Y為諧波導(dǎo)納陣），就可以確定各處的節(jié)點(diǎn)諧波電壓了。進(jìn)而可求出潮流功率。其計(jì)算步驟如下：<1>、根據(jù)所給運(yùn)行條件，以通常的潮流計(jì)算方法求解基波潮流。<2>、按諧波源工作條件，確定其它有關(guān)參數(shù)及需要計(jì)算的諧波次數(shù)。<3>、計(jì)算各元件諧波參數(shù)，形成各次諧波網(wǎng)絡(luò)節(jié)點(diǎn)導(dǎo)納矩陣，并計(jì)算相應(yīng)諧波網(wǎng)的注入電流。<4>、由式IN=YNUN確定各節(jié)點(diǎn)的諧波電壓，并計(jì)算各支路諧波功率。其中，應(yīng)注意有諧波儀測出的諧波注入電流，其相角是相對于基波電流的相角。故求出基波電流后，需將諧波注入電流相角進(jìn)行修正。同樣，系統(tǒng)節(jié)點(diǎn)的功率是基波功率與諧波功率之和，故基波注入功率也應(yīng)進(jìn)行

14、修正。但線性負(fù)荷處的基波注入功率不必修正。（2）、不對稱系統(tǒng)諧波潮流計(jì)算在不對稱系統(tǒng)中，三相情況各不相同，而且相互影響，因此必須同時進(jìn)行三相系統(tǒng)的計(jì)算。不對稱網(wǎng)絡(luò)潮流的計(jì)算可將網(wǎng)絡(luò)分為各次諧波網(wǎng)絡(luò)，先計(jì)算基波網(wǎng)絡(luò)，求得各節(jié)點(diǎn)基波電壓后，按它計(jì)算各諧波潮流的各次注入電流，再按此諧波注入電流解算各次諧波的網(wǎng)絡(luò)方程，求出各節(jié)點(diǎn)的各次諧波電壓。四總結(jié)電力系統(tǒng)中諧波的出現(xiàn)，對于電力系統(tǒng)運(yùn)行是一種"污染"。它們減少了系統(tǒng)電壓正玄波形的質(zhì)量，不僅嚴(yán)重地影響了電力系統(tǒng)自身，而且也損害了用戶和周圍的通信系統(tǒng)。因此對電力系統(tǒng)諧波的研究對于改善電能質(zhì)量，抑制和消除諧波具有十分重要的意義。Powe

15、r system harmonic analysis and harmonic tidal calculationFirstly, the ideal electrical power system is supplied by a regulated voltage source that has a single and constant frequency and specified amplitude . But in fact, with the development of science and technology in recent years, the use of hig

16、h - power commutation devices and regulating devices, the applications of HVDC ，the emergence of a large number of non-linear load as well as the power supply system itself and so on that have cause a distortion which is more and more serious to the Voltage waveform, which has caused very great harm

17、 to the electrical power system. For example: it can Causes the Component Losses in the power supply system more serious, reduce the life of electrical equipment, disturb the communication system and so on. It can also damage the equipment, result in automatic control malfunction and cause the misop

18、eration of relay protection. Thus cause the power outage accident and other questions. So-called "Know me and know thee, lose none and win all ", therefore, if you want to Comprehensive manage the , you must make clear the harmonic sources and distribution grid of harmonic power flow in a

19、variety of different operating modes , then you can take appropriate measures to limit and eliminate harmonics to improve power quality of the power supply system and ensure the safety of system with economic operation . Secondly, the source of electrical power system overtone has a varied forms. It

20、 mainly has the following several kinds: 1, system's each kind of nonlinear electric equipment. For example: Converter equipment, regulator device, electrified railway, electric-arc furnace, fluorescence the lamp, the domestic electric appliances and kinds of electronic energy conservation contr

21、ol device and so on are the important source of electrical power system overtone. Even if these equipment supplies the ideal sine wave voltage, the electric current it takes is also non-linear, namely the harmonic current exists. And the harmonic current the equipment produces will also pour into th

22、e electrical power system, which will cause existence of harmonic component in the system voltage of each place. The overtone that has nothing to do with the electrical power system parameter in these equipment decided its characteristic and working condition, which maybe regarded as source of the o

23、vertone with constant flow. 2, the overtone generated by the nonlinear element in the power supply system itself is another origin. There are many kinds of nonlinear element. For example: transformer excitation branch , Ac/dc converter thyristor control element, thyristor controlled capacitor, react

24、or, etc.3, The harmonic component produced by user electric equipment will also impact on the system. Such as fluorescent lamps, household appliances with a small capacity has a large quantity and spread in everywhere.So the power sector has difficulty in managing such equipment. If harmonic content

25、 current of these devices is too large, it will cause serious impact to power system,and the manufacturing number of the current harmonic content of this kind of equipment should be limited in a certain range.4, Harmonic voltage from generator is another source. Generator is sued to produce the rate

26、d voltage but at the same time also engender harmonic voltage which is determined by the structure and the working conditions of the generator.And harmonic voltage has nothing to do with external impedance that can be treated as the harmonic constant voltage source, but its value is very small.Third

27、ly, The calculation of power system harmonic power flow is completed by solve the network equations In = YnUn (n = 3, 5, 7. n: number of harmonics. In: Harmonic currents n times column injected into power grid by load that is considered as the harmonic source . Yn: n times harmonic admittance matrix

28、 of power grid. Un: n times harmonic voltage of each bus nodes in the grid column). We can get the power grid harmonic voltage of each node (bus) then the harmonic current of each current branch.When there are harmonic sources exist in the power system, the system of contact voltages and branch curr

29、ents will have higher harmonic. In order to determine the distribution of harmonic voltage and harmonic current in power supply system , we need do calculation of power flow for equivalent circuit consisted by harmonic impedance.At the same time, when capacitive component exist in rectifying device

30、in the power supply system, also according to the nature and size of each branch of harmonic impedance to verify presence of resonance condition.To do harmonic power flow calculation, we must determine the harmonic impedance of power grid element first.3.1 Power grid harmonic impedance of all kinds

31、of components:1. Harmonic impedance of synchronous generatorQualified potential is pure sine generator, do not contain high order harmonic, the generator voltage is only the base network.In higher harmonic network, due to the harmonic voltage generator is very small, we can regard harmonic voltage g

32、enerator as zero at this time. Therefore, its equivalent circuit is harmonic reactance that connected to the machine side and neutral.The XGn = nXG1 - - - - - - - - - - - - - (1) Type of XG1 is fundamental wave generator, positive sequence and negative sequence based on the zero sequence reactance d

33、ecided by the characteristics of harmonic sequence. if needs to take lose of the network into consideration, estimates that the generators impedance angle according to 85 degrees, regarding the transmission line, part's and so on transformer and load equivalent generators, may its impedance angl

34、e according to 75 degrees . 2.Harmonic impedance of transformer Power system harmonic with the increase of frequency and amplitude attenuation is often change, so often ignore the excitation transformer branch and turn-to-turn capacitive when calculating the base wave method especially in high volta

35、ge grid. When calculating the harmonic current, only consider the transformer leakage reactance, and think that is proportional to the harmonic frequency determined by the frequency. In the general case, the transformer equivalent circuit is simplified as the former vice edge connection node and one

36、 of the fundamental harmonic reactance is transformer leakage reactance.Under the action of high order harmonic, the skin effect and the adjacent effect inside the winding increases, then the of the transformers resistance is proportional to the square of the number of times for the harmonic, the ha

37、rmonic impedance for the transformer:Zn= SQRT (n) + jnXT1 RT1 - - - - - - - - - - - (3)The RT1 is fundamental wave resistance of a transformer.For three-phase winding transformer, the radial equivalent circuit can be used, the calculation method of the harmonic impedance is same above.When the three

38、-phase of higher harmonic current injected in harmonic sources are asymmetric, three-phase harmonic impedance can be calculated according to the connection mode of the transformer and each sequence impedance.3.Harmonic impedance of reactor. When only consider reactor inductance, the NTH harmonic fre

39、quency is: XLn = Nxl * UN/SQRT (3) IN4.Harmonic impedance of the transmission lineThe distributed parameter of transmission lines are uniform, the transmission line is considered to be a three-phase symmetrical after complete transposition. In the calculation of power flow, it usually be expressed a

40、s PI type equivalent circuit with a lumped parameter.Under the consideration of the meter and the distribution characteristics, then:ZLn=Znsh(rnl)Yln/2=(chrnl-1)/(Znshrnl)Zn and RN: the line impedance and the harmonic propagation constant.The Zn = SQRT (Z0n/Y0n) Rn = SQRT (Z0nYon)Z0N and Y0N: the ha

41、rmonic impedance and admittance of per unit length of transmission lines5.Harmonic impedance of load In the calculation of harmonic power flow, the fundamental part can be regarded as the power injected by node, but it often be seen as a constant impedance in harmonic network, approximately integrat

42、ed load can be thought of as an equivalent motor. Equivalent impedance values of the comprehensive load harmonic:ZN=SQRT（N）R1+JNX1R1, the X1 : the fundamental negative sequence resistance of equivalent motor, reactance, its value can be calculated by base waves voltage and power of the node.Not to l

43、oad in the zero sequence current, so negligible load branch can be ignored in the higher harmonic zero sequence sex network because there is no zero-sequence current in load Under normal circumstances.When the harmonic impedance of each electric component are determined in the circuit, a harmonic eq

44、uivalent circuit can be formed and calculated, in order to draw equivalent circuit under the action of harmonic , should pay attention to the following features:1.Equivalent circuit under the action of harmonic and shall be centered on rectifying device, according to the actual wiring, so regard the

45、 rectifier device as a source of harmonic, and power system energy generator is not to appear, but as part of the harmonic source load impedance.2.Circuit components impedance can be calculated by using a name value and also using the MAO values to calculate. When using a name values to calculate, a

46、ll should be converted to a voltage reference circuits, in order to facilitate analysis and application.3.The resistance of all component can be ignored in general calculation, but when one part of the system or nearly parallel or series resonance occurs, the influence of the resistance cannot be ig

47、nored.4.Harmonic current is determined by total harmonic current of the rectifying device side in the approximate calculation, the selection of harmonic current and voltage distribution can be determined according to equivalent circuit of the harmonic.3.2 The calculation of harmonic power flow 3.2.1

48、 The calculation of harmonic power flow without capacitive element network (1). Calculation of harmonic power flow in the symmetric systemThree-phase system is the same in the Symmetric system, so you can make a calculation according to consideration of one phase.When the total harmonic current of t

49、he rectifying device either side is determined, the harmonic current distribution of the system at any branch in the network can be determined according to harmonic equivalent circuit. Then according to the node harmonic voltage and harmonic current injected by the node I = YU (among them, Y : harmo

50、nic admittance matrix), the harmonic voltage of various nodes can be determined. And then the power of the tidal current can be worked out. The calculation steps are as follows:< 1 >. The fundamental wave tide can be calculated by using the usual flow method according to the given operating co

51、nditions.< 2 >.According to the working conditions of harmonic source, other relevant parameters and harmonic frequency will be computed.< 3 >.Calculate the component of harmonic parameters, form every harmonic network node admittance matrix, and calculate the current injected in the cor

52、responding harmonic net.< 4 >. Harmonic voltage of each node is determined by the type = YNUN IN and harmonic power of each branch is calculated.Among them, attention should be paid to harmonic current measured by the harmonic meter injected in current, the phase Angle is observed in current p

53、hase Angle. So after the calculation of the fundamental wave current, the phase Angle of the injected harmonic current must be amended. Also, the system power of a node is the sum of power of fundamental wave and harmonic power, so the injected fundamental wave power should also be revised. But fundamental wave power that injected of linear load don't have to be corrected.(2),Calculation of asymmetric system harmonic power flow In the asymmetric three-phase system, the t conditions of each phase are not identical, and influence each other, so the calculation of three-phase system