Lecture+5_Three+Phase+Power+Part+1.pdf - Overview • Homework#2 Posted tonight and due next Monday • Review – Power Factor Correction • Today –

Lecture+5_Three+Phase+Power+Part+1.pdf - Overview •...

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Overview Homework #2: Posted tonight and due next Monday Review Power Factor Correction Today Node Equations Three-phase power 1 Lyles College of Engineering, Fresno State Dr. K. McBee
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Review - Example 2.4 How do we solve? Identify the current VARS 2 Lyles College of Engineering, Fresno State Dr. K. McBee p.f. angle
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Review - Example 2.4 b) Identify the added load 3 Lyles College of Engineering, Fresno State Dr. K. McBee
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Review Real Power, Complex Power, Apparent Power Power and Impedance Triangle Power Factor Corrections 4 Lyles College of Engineering, Fresno State Dr. K. McBee
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Review - PowerWorld A software designed for assisting engineers in performing “ Power System Simulations An electric grid is too large to build a laboratory model to examine how fluctuations in load and generation will affect the power system Power engineers rely upon simulation tools to Design upgrades Evaluate system voltage (ANSI Standard C84.1 voltage limits) Evaluate system stability Recreate failure events Software example 5 Lyles College of Engineering, Fresno State Dr. K. McBee
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Power Grid is a network How do we analyze a large system consisting of numerous lines, nodes, and buses? How do we model a system? Powerflow software is useful in modeling entire system, but how to engineers add to the model when changes occur? 6 Lyles College of Engineering, Fresno State Dr. K. McBee
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Power System Analysis Picture of Denver distribution system 7 Lyles College of Engineering, Fresno State Dr. K. McBee
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Power System Analysis Picture of Denver 8 Lyles College of Engineering, Fresno State Dr. K. McBee
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Power System Analysis Picture of Denver - with transmittion lines 9 Lyles College of Engineering, Fresno State Dr. K. McBee
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Network Equations 10 Lyles College of Engineering, Fresno State Dr. K. McBee
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Network Equations Circuit operating in sinusoidal-steady state, Kirchhoff’s current and voltage law still apply to phasors Many times a network (grid) is analyzed as complete system, instead of analyzing a single quantity Transmission systems can consists of hundreds of nodes, which limits simple solutions A system is modelled by connection to buses (or nodes) 11 Lyles College of Engineering, Fresno State Dr. K. McBee 4 Bus Example
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Node Analysis Review Node v 1 Node v 2 12 𝑖 1 = 𝑖 2 + 𝑖 3 𝑖 3 = 𝑖 4 + 𝑖 5 Lyles College of Engineering, Fresno State Dr. K. McBee
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Node v 1 13 10v − 𝑣 1 = 𝑣 1 + 𝑣 1 − 𝑣 2 1.58𝑣 1 − 0.33𝑣 2 = 10 𝑖 1 = 𝑖 2 + 𝑖 3 Lyles College of Engineering, Fresno State Dr. K. McBee
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14 𝑣 1 = 7.33v 𝑣 2 = 4.77v 1.58𝑣 1 − 0.33𝑣 2 = 10 −0.33𝑣 1 + 1.03𝑣 2 = 2.5 Lyles College of Engineering, Fresno State Dr. K. McBee
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Network Equations For system with over hundreds of nodes, computer simulations are formulated from nodal equations, which are systematically applied to circuits Assumptions Sinusoidal Source voltages represented by phasors Circuit impedances are measured in Ohms 15 Lyles College of Engineering, Fresno State Dr. K. McBee
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