THE ANALYSIS AND CALCULATION OF ELECTROMAGNETIC FIELD AROUND OVERHEAD POWER LINE HongWang Yang

Transcription

1 5th Interntionl Conferene on Advned Mterils nd Computer Siene (ICAMCS 6) THE ANALYSIS AN CALCULATION OF ELECTROMAGNETIC FIEL AROUN OVERHEA POWER LINE HongWng Yng eprtment of eletril engineering, North Chin Eletri Power University, Boding 7, Chin Keywords: eletromgneti field, Power System Anlysis, Biot-Svrt Lw Astrt. istriution networ is the onnetion of the generte system nd trnsmission line, whih is t the lst stge of the proess of the energy trnsporttion. It is omple to judge the diretion of the power flow, so tht it is signifint to study more effetive method to judge the diretion of the power flow in the Overhed power line. This pper introdues the priniple of the Biot-Svrt Lw firstly nd then introdues the neessity of power system simultion,. To omplete the nlysis nd lultion of eletromgneti field round Overhed power line when Signls Phse Erth Fult our in the power system, the sptil retngulr oordinte system ws estlished sed on the rrngement of the Overhed power line. After the study of KV distriution networ we rete fult simultion pltform ATPrw nd sed on MATLAB simultion softwre, we use the eletromgneti trnsient progrm grphil input funtion nd the strong lultion funtion of MATLAB to lulte eletromgneti field round Overhed power line, so s to provide the sis for further nlysis.. Introdution The Mgneti indution db,whih produed y urrent element Idl t point P in spe, is proportionl to the vlue of the urrent element Idl nd the sine of the ngle etween the position vetor tht pointing the urrent element to the point P with the vetor of urrent element Idl,nd inversely to the distne etween Idl nd point P. u In former formul is the rtio oeffiient u is vuum permeility whose vlue is 4π 7 4π T * m / A nd the diretion is perpendiulr to the surfe determined y the urrent element nd vetor r urve the finger nd the diretion of thum is the diretion of db.tht is Idl,dB nd r ord the right-hnd srew rule. The lw of Biot Svrt is proved y the H.C. Oster eperiment. The eperiment illustrte tht the fore whih is given y long stright urrent-rrying to the mgneti pole is horizontl fore. J.B. Biot nd F.Svrt elieve tht the fore tht urrent element gives to mgneti pole is perpendiulr to the surfe determined y urrent element nd the mgneti pole, in sme wy, horizontl fore. They me onlusion out the reltionship etween the fore nd the ngle of the uing urrent-rrying,s well s the reltionship with distne vi the eperiment tht mesure the fore given y stright nd urve urrent-rrying to the mgneti sole. With the help of P.S.M. Lple, they got the rule of the effet of the urrent element to the mgneti pole. Aording to the view of the lose rnge funtion,the onlusion is understnd y puli s rule of the prodution of mgneti field.. Model. Model ssumptions ) Assume tht the Three-phse Conduting Wires of Overhed Trnsmission Line is in the in the tringle rry. 6. The uthors - Pulished y Atlntis Press 38

2 Symols ( efinitions X, Y ) the oordinte of the Three-phse Conduting Wires of Overhed Trnsmission Line S the oeffiient of horizontl mgneti field W the vertil mgneti field oeffiient (, y) the lotions of the sensors i the zero sequene urrent i Positive sequene urrent i Negtive sequene urrent ) The wether is norml. 3) There is no other mgneti field nd eletri soure in the field.. Symols nd definitions.3 the model of mgneti field Aording to tehnil speifition for design of overhed distriution lines,power distriution line minly dopts tringle rrngement or horizontl lignment.a three-phse ondutor is infinitely long nd is prllel to the ground, The instntneous urrent in the three phse wire is I, I, I.We set up oordinte system in plne perpendiulr to the three-phse wire s shown in the figure elow.three phse ondutor oordintes is (X,Y),,,, the oordintes of the testing point P is(,y). Figure Power line round the mgneti field lultion The horizontl omponent of the mgneti indution intensity of P n e represented B Si + Si + Si s: where Y y S π ( X ) + ( Y y) Y y S π ( X ) + ( Y y) Y y S π ( X ) + ( Y y) Among them S,S,S is the oeffiient of horizontl mgneti field, u is the ir permeility. The vertil omponent of the mgneti indution intensity of P is: B Wi + Wi + Wi y Among them W,W,W is the oeffiient of vertil mgneti field,u is the ir permeility. When the onstrint onditions re met, the oeffiient of vertil mgneti field n e desried: W W W X π X π X π Aording to Krrenuer Trnsform, vertil mgneti field is represented s followers: B Wi + Wi + Wi Where: y W W + W + W ; W W W + W ; W W + W W 383

3 As is shown in the Figure, Three-phse line is symmetry out tower nd three-phse iruit meet the following reltionship: X X X Where d is horizon distne etween two-phse iruit in outside nd the tower. The oeffiients n e simplified s: The vertil mgneti field is: d 3 W π W 3 d W π i + di π 3 ( ) Speilly, When the nery hepoint P loted just elow the line, in other words, when d >>, the vertil mgneti field is: 3 d i π Tht line just elow the vertil filed is proportionl to the urrent nd negtive sequene. When the hepoint is met,the vertil mgneti field is: 3 i π Tht is, when the point is fr wy from the three-phse line in the horizontl diretion, vertil mgneti filed proportionl to the zero sequene urrent. 3. The nlysis of eletri field Using equivlent hrge, we n lulte the eletri filed strength round the three-phse overhed lines, whih is shown s figure. Figure eletri filed oordinte system Assuming the three phse ondutor disposed oordintes is( X, Y ),,,,deteting oordintes of point P is (, y).provided tht ground potentil is nd A,B, C,for the three phse ondutors of potentil respetively is u, u, u ; Unit length of the line were the equivlent hrge is,,. We n get tht: λ λ λ3 u u λ λ λ3 u λ u λ3 λ3 λ33 u u Where λ is self potentil oeffiient of eh wire nd potentil oeffiient mtri, whih n e otined ording to the method of imges.vertil eletri filed E y deteted y the three-phse voltge t the ommon point P generted nd Horizontl eletri filed E re defined s follows: T E y [ L, L, L ][,, ] E [ H, H, H ][,, ] T 384

4 Where L H πε ( X y Y ) + ( y Y ) X πε ( X ) + ( y Y ) ( X y + Y ) + ( y + Y ) + X ( X ) + ( y + Y ) 4. Conlusion After run in the ATP-EMTP we n otin the Current imge: 8 [A] [A] [ms] 7 (file d.pl4; -vr t) :3A -X4A :3B -X4B :3C -X4C [ms] 7 (file d.pl4; -vr t) :3A -X4A :3B -X4B :3C -X4C Figure 3 the Current imge To lulte the eletromgneti,we progrm in MATLAB.it is run s flows: Figure 4 eletromgneti imge istriution networ is the onnetion of the generte system nd urrent-rrying, whih is t the lst stge of the proess of the energy trnsporttion. The qulity of the eletriity in onsumers fmily is losely relted to the sitution of the distriution net wor. However, the proility tht networ our single-phse-to-ground fult is etrordinry high. The line voltge mong three phses remin unhnged,nd the redown urrent is smll, the iruit-reer does not ut the iruit, nd the system n eep woring for period fter the fult hppened. But the rise of the phse voltge nd the r t ident point will use the eletril short-iruit nd the destroy if the equipment. So it is vlule to disover effiient equipment to distinguish the redown signl. Write the formul in Mtl, lulte the trnsverse omponent B nd the longitudinl omponent of the intensity of the mgnetiztion of the point whih is underneth two detetive point efore nd fter the ident point for 3 meters. Compre 4 wve ptterns intensity of themgnetiztion, we n get the influenes tht utting-out redown gives to the mgneti field t different point. Anowledgments The ontent of this thesis is supported y the ollege students innovtions speil projet(seril Numer: 5545) Referene []. Sun B, Xue Y, Sun T, et l. A Fult Current Mesurement Method for Single Phse Grounding of Non-solidly Erthed Overhed Lines[J]. Automtion of Eletri Power Systems, 8. [].Li C, Tyjsnnt T, Xu W, et l. Method for voltge-sg-soure detetion y investigting slope of the system trjetory[j]. IET Proeedings - Genertion Trnsmission nd istriution, 3, 5(3):

5 [3].Sun B, Zhng C H, Sun T J, et l. Erth fult lotion sed on trnsient phse urrent in non-solidly erthed networ[j]. Power System Protetion & Control,. [4].Zhenun L I, Chen X, Liu H, et l. Online Assessment of istriution Networ Loding Cpility[J]. Automtion of Eletri Power Systems, 9, 33(6):