POWER SYSTEM ANALYSIS IGEE-402 MID-TERM November 11, 2009 Open book and notes, Prof. F.D. Galiana Maximum of 90 points Problem 1– The phase currents drawn by a three-phase load are equal to the sum of two components, 1abcIand2abcI. As shown below, the first component is known in phase coordinates but the second current component is known in symmetrical components, all in per unit, 1211abcI⎡⎤⎢⎥=−−⎣⎦2012110I⎡ ⎤⎢ ⎥=⎢ ⎥⎢ ⎥⎣ ⎦(a)Find the positive sequence current drawn by the three-phase load. (10) (b)Can this three-phase load be a delta-connected load? Explain. (10) (c)Find the ground current. (10) Problem 2- A three-phase balanced load is connected in form of a wye with branch admittances 2+j and connected to ground through a branch with admittance 1+j. All quantities are in per unit. (a) If the load is connected to a positive sequence voltage source with magnitude 10, find the real
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