Report on Symmetrical Components

Report on Symmetrical Components - BUFFALO STATE COLLEGE...

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BUFFALO STATE COLLEGE DEPARTMENT OF TECHNOLOGY ENT 472 Power Systems II COURSE PROJECT Spring 2010 Report on Symmetrical Components Single Line diagram of a three phase power system: G1 1000 MVA 15 kV X d = X 2 = 0.18, X 0 = 0.07 pu Y-grounded G2 1000 MVA 15 kV X d = X 2 = 0.20, X 0 = 0.10 pu Y-ungrounded G3 500 MVA 13.8 kV X d = X 2 = 0.15, X 0 = 0.05 pu Y-grounded through reactance G4 750 MVA 13.8 kV X d = 0.30, X 2 = 0.40, X 0 = 0.10 pu Y-ungrounded T1 1000 MVA 15 kV / 765 kV X = 0.10 pu Delta -- Y-grounded T2 1000 MVA 15 kV / 765 kV X = 0.10 pu Delta -- Y-grounded T3 500 MVA 15kV / 765 kV X = 0.12 pu Y-ungrounded – Y-grounded T4 750 MVA 15 kV / 765 kV X = 0.11 pu Y-grounded – Y-grounded
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1 - 2 765 kV X 1 = 50 Ohm, X 0 = 150 Ohm 1 - 3 765 kV X 1 = 40 Ohm, X 0 = 100 Ohm 2 - 3 765 kV X 1 = 40 Ohm, X 0 = 100 Ohm Given that the inductor connected to generator 3 neutral has a reactance of 0.05 pu using generator 3 ratings as a base. Calculating the per unit line impedances S base =1000MVA, V base =765kV. R base = [(765) 2 *(10) 6 ]/[1000*(10) 6 ] = 582.225Ω For line 1-2, X 1-2 = 50/582.225 = .0854 p.u, X o(1-2) = 150/582.225 = 0.2563 p.u For line 1-3, X 1-3 = 40/582.225 = .0683 p.u, X o(1-3) = 100/582.225 = 0.1709 p.u For line 2-3, X 2-3 = 40/582.225 = .0683 p.u, X o(2-3) = 100/582.225 = 0.1709 p.u Calculation of new per unit impedances of generators and transformers Since the generator G3 and G4 are at different MVA and kV, converting them to 1000MVA power and 15kV voltage, we have new per unit impedances for these generators. These are calculated as follows: Generator G3: X new p.u = X old p.u * (V old /V new ) 2 * (S new /S old ) X g13 = X g23 = .15 * (13.8/15) 2 * (1000/500) = 0.2531 p.u X g03 = .05 * (13.8/15) 2 * (1000/500) = 0.0846 p.u Generator G4: X g14 = .30 * (13.8/15) 2 * (1000/750) = 0.3378 p.u X g24 = .40 * (13.8/15) 2 * (1000/750) = 0.4504 p.u X g03 = .10 * (13.8/15) 2 * (1000/750) = 0.1128 p.u Similarly the new per unit impedances for transformers are calculated Transformer T3 : X T13 = 0.12 * (15KV/15KV) 2 * (1000MVA/500MVA) = 0.24 p.u Transformer T4:
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X T14 = 0.11 * (15KV/15KV) 2 * (1000MVA/750MVA) = 0.1467 p.u 1. SEQUENCE DIAGRAMS a) Positive Sequence: Fig 1 b) Negative sequence
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Fig 2 c) Zero Sequence Fig 3 2. THEVENIN EQUIVALENT NETWORKS:
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Report on Symmetrical Components - BUFFALO STATE COLLEGE...

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