lecture2 - EEL 6266 Power System Operation and Control...

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Unformatted text preview: EEL 6266 Power System Operation and Control Chapter 3 Numerical Methods for Economic Dispatch © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 2 The Lambda-Iteration Method & The solution to the optimal dispatch can be approached by graphical methods ¡ plot the incremental cost characteristics for each generator ¡ the operating points must have minimum cost and satisfy load & that is, find an incremental cost rate, λ that meets the demand P R & graphically: Σ d F 1 d P 1 ($/MWh) d F 2 d P 2 ($/MWh) d F 3 d P 3 ($/MWh) P 1 (MW) P 2 (MW) P 3 (MW) P R = P 1 + P 2 + P 3 λ © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 3 The Lambda-Iteration Method & An iterative process ¡ assume an incremental cost rate λ and find the sum of the power outputs for this rate & the first estimate will be incorrect ¡ if the total power output is too low, increase the λ value, or if too high, decrease the λ value & with two solutions, a closer value of total power can be extrapolated or interpolated ¡ the steps are repeated until the desired output is reached λ [1] λ [3] λ [2] [1] [3] [2] λ error ( e ) solution: (| e | < tolerance) R N i i P P e- = & = 1 Lambda projection © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 4 The Lambda-Iteration Method & This procedure can be adopted for a computer implementation ¡ the implementation of the power output calculation is rather independent of the solution method & each generator output could be solved by a different method ¡ as an iterative procedure, a stopping criterion must be established & two general stopping rules are appropriate for this application ¢ total output power is within a specified tolerance of the load demand ¢ iteration loop count exceeds a maximum value start set λ calculate P i for i = 1 to N calculate & =- = N i i load P P 1 ε first iteration? | ε | ≤ tolerance? project λ print schedule end © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 5 The Lambda-Iteration Method & Example ¡ consider the use of cubic functions to represent the input- output characteristics of generating plants ¡ for three generating units, find the optimum schedule for a 2500 MW load demand using the lambda-iteration method & generator characteristics: & assume that the fuel cost to be $1/MBtu & set the value of λ on the second iteration at 10% above or below the starting value depending on the sign of the error ( 29 ( 29 MW in MBtu/h 3 2 P DP CP BP A H + + + = Unit 1 749.55 6.95 9.68 × 10-4 1.27 × 10-7 320 800 Unit 2 1285.0 7.051 7.375 × 10-4 6.453 × 10-8 300 1200 Unit 3 1531.0 6.531 1.04 × 10-3 9.98 × 10-8 275 1100 A B C D P max P min © 2002, 2004 Florida State University EEL 6266 Power System Operation and Control 6 The Lambda-Iteration Method & Example ¡ initial iteration: λ start = 8.0 & incremental cost functions & find the roots of the three incremental cost functions at...
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This note was uploaded on 10/28/2009 for the course EEE 252 taught by Professor Jhon during the Fall '09 term at CSU Sacramento.

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lecture2 - EEL 6266 Power System Operation and Control...

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