LineConstantsHKH - 1 Transmission line parameters line...

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1 ransmission line parameters Transmission line parameters •A i m Learn how to use ATP to obtain series impedance parameters; ontents • Contents – Introducing the ground reference – Self and mutual impedances – Matrix description – Look into ATPDraw LCC module xamples – Examples MTU-Houghton, 2010 Internett: www.elkraft.ntnu.no/
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2 riefly about the speaker Briefly about the speaker rofessor at Norwegian Univ Science and Professor at Norwegian Univ. Science and Technology – Dept. Electrical Engineering – Power system transients and protection – High voltage engineering, stress calculations – Recent focus on Power Transformers • Honorary member of European EMTP user’s group – User of ATP for 20 years • Developer of ATPDraw • Sabbatical at MTU – Room 628, phone 487-2910 – hhoidale@mtu.edu
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3 Relevance of series impedance parameters • Why do we have to understand the details? he manufacturer provides only positive The manufacturer provides only positive sequence 50/60 Hz data! – Zero sequence data important for ground fault situations! – Mutual coupling between parallel transmission es is important for protection settings! lines is important for protection settings! – What is the influence of • Transmission line height, h • Phase separation, D • Bundling, duplex/triplex round resistivity • Ground resistivity, MTU, Houghton, 2010 www.elkraft.ntnu.no/
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4 round plane Ground plane • The text book chapt. 4 handles only conductors in free space. Let us introduce a ground plane: DD I a I b I a I b Air ir I a I b h 1 h h 1 h Air -I a -I b Earth Air Air 2 h 1 h 2 2 h 1 h 2 ‘Air’ -I a -I b Field lines erpendicular Ideal case: aging concept Real case: enetration MTU, Houghton, 2010 www.elkraft.ntnu.no/ perpendicular to earth surface Imaging concept Penetration depth of earth
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5 ternal self impedance Internal self impedance • Self impedance is split in internal and external part si e Z ZZ  • Internal impedance (round, solid cond.): Rj Eq. 4.2 & 4.13 in text book. 8 ii ZRj Depends on skin effect and geometry. GMR available. • The last part is often written on the form 00 4 r r j j e     q 4 23 in text book MTU, Houghton, 2010 www.elkraft.ntnu.no/ ln 82 4 2 jj     Eq. 4.23 in text book.
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6 xternal self impedance External self impedance • A conductor over an ideal, lossless ground (Eq. 4.22 in text book): 2 r – Imaging:  h =0 h • A conductor over a real earth surface 0 2 ln 2 e j h Z r       /m] image – Penetration depth (or Carson’s formula) or low frequencies ( >> m]
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LineConstantsHKH - 1 Transmission line parameters line...

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