2009-09-17 The Utilization of Electric Energy

2009-09-17 The Utilization of Electric Energy - The...

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The Utilization of Electric Energy Jovan Ilić ECE 18-418 Fall 2009
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Introduction • Gen->Transmission->Distribution->Utilization • Supply variable P/Q at as constant as possible voltage and frequency • Demand types (P/Q): – Mechanical – Thermal – DC – Chemical • Customers: industrial, commercial, residential
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Note: From Electrical Power system Essentials Daily load curve in the Netherlands (Monday May 15, 2006)
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Mechanical Loads • Mostly rotating machines powered by synchronous and induction motor • Single phase (low power) motor • Large loads industrial machines with high startup currents • Industrial installations requiring reactive power support
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The Synchronous Motor Magnetic field generated by a three-phase coil system Note: From Electrical Power system Essentials
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The Synchronous Motor Synchronous motor connected to an infinite bus Note: From Electrical Power system Essentials
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The Induction Motor Model [1]
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  24 ˆ ˆ ˆ cos 33 sa s s sb s s sc s s i i t i i t i i t  The current in stator windings are given as:
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    0 cos 2 s s sa s sa s N Bi    0 2 cos 23 s s sb s sb s N        0 4 cos s s sc s sc s N Contributing to flux density components: after substituting currents:                 0 0 0 1 ˆ cos cos 22 14 ˆ cos cos 2 2 3 12 ˆ cos cos 2 2 3 s s sa s s s s s s s s sb s s s s s s s s sc s s s s s s N B i t t N B i t t N B i t t   
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          0 3 ˆ cos 22 s s s s s s s sa s sb s sc s s s s N B B B B i t     1 ˆ ss s s s s s B B t  Total flux density is given by: In the rotor reference frame: and sr      1 ˆ r s r s s s B B t   number of turns in stator windings air gap size between the stator and rotor s N
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Flux linkages between the stator and rotor? For single rotor winding case, as usual, the flux over half cylinder is:       22 ,1 ˆ cos 2 cos length of the machine radius of the rotor r rd s s r r s s r r S rd s s s B ndA B lrd B lr t d B lr t l r     and the flux linkage:     , , 1 , ˆ ˆ 2 cos rd s r rd s r s s rd s N N B lr t t , number of turns of rotor winding ˆ
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This note was uploaded on 09/20/2010 for the course ECE 18418 taught by Professor Illic during the Fall '09 term at Carnegie Mellon.

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2009-09-17 The Utilization of Electric Energy - The...

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