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Unformatted text preview: EEL 6266 Power System Operation and Control Chapter 4 Transmission System Effects © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 2 Overview c The network’s incremental power losses causes a bias in the optimal economic scheduling of the generators r the total real power loss increases the total generation demand c the power flow forms the basis for the development of loss factors for predicting the real power loss r the generation schedule may need to be adjusted by shifting generation to reduce flows on transmission circuits because they would otherwise become overloaded c difficult to include the last effect into optimum dispatching c the power flow must be solved to check for violations © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 3 The Power Flow Problem c Power flow is the name given to a network solution that shows currents, voltages, and active & reactive power flows at every bus within the system r assumptions c balanced system  positive sequence solution only c simple generation and load models r nonlinear problem c relates active and reactive power consumption and generation with voltage magnitudes r uses c design procedures (system planning) c study unique operating problems c provide accurate calculations of loss penalty factors © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 4 The Power Flow Problem c The power flow problem consist of a given transmission network r lines are represented by a piequivalent circuit r transformers are represented by a series impedance circuit r generators and loads represent the boundary conditions c loads are given as active and reactive power consumptions c generators are usually described by the active power production and the terminal voltage c The general power flow equation r one set of equations for each bus in the network ( 29 ( 29 ( 29 ( 29 ( 29 ( 29 ∑ ∑ = = = + = N k k i ik k i ik k i i inj N k k i ik k i ik k i i inj B G E E Q B G E E P 1 1 cos sin sin cos θ θ θ θ θ θ θ θ © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 5 The AC Power Flow c Formulation of the power flow r building the busadmittance matrix c modeling the transmission network of complex impedances as related to the system buses s includes line, transformer, and shunt element impedances c general construction rule s if a branch exists between nodes i and j , and where j is defined for all branches connected to i ∑ + = = j ij i ii ij ij y y Y y Y © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 6 The AC Power Flow r define bus characteristics based on typical information available Power flow bus specifications Bus Type Active Power, P Reactive Power, Q Voltage Magn., E Voltage Angle, θ Comments Constant Power Load, Constant Power Bus Scheduled Scheduled Calculated Calculated Standard load representation Load / Shunt Element,...
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 Fall '09
 Jhon
 Electrical Engineering, Florida State University, Electric power transmission, Power flow study, Power System Operation and Control

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