Economic Dispatch of Combined-Cycle Generators

May06-07

Client: MidAmerican Energy Company

Alan Oneal

Faculty Advisors:Dr. John Lamont

Students:Matthew Ellis, EE

Noraima Fernandez, EEJeremy Hamilton, EE

Robert Walter, EE

Presentation Overview

Background Material Previous Teams’ Contributions Project Team Goals

Main Menu Overall Structure Unit Commitment Output Data Time Permitting Work

Conclusion/Questions

Usability

Acknowledgements

The senior design project team would like to acknowledge:

Alan OnealAlan Oneal of MidAmerican Energy as our client contact for the project

Dr. LamontDr. Lamont for advising and overseeing the project

Overall Project Idea

To incorporate combined-cycle generator units into the current power system to meet peak load emergency

To solve for economic dispatch of monotonic and non-monotonic units, providing the least cost solution

Monotonic(MU)→ ←Non-Monotonic (NMU)

General Problem Statement

The project involves: modification of an algorithm

incorporated into Microsoft Excel macros offering a low-cost and time efficient solution in meeting power demand

use of monotonic and non-monotonic generation systems to provide more cost effective generation dispatch combinations

Initial Project Work 1/5

Overview Data Loading and Verification

User specified Excel fields are read into a corresponding VB data array

Data is checked to assure it’s in the correct format and none is missing If data is incorrect an error window pops into

the screen and a log is produced

What’s already been accomplished by prior teams….

Initial Project Work 2/5

Algorithm (How does it work?)1. MW vs. IHR and I/O are used to calculate A,

B, and C coefficients relating each generator’s power and cost

Fuel = Ax2 + Bx + C x = Power (MW)

dF/dX = IHR = 2Ax + B

Initial Project Work 3/5

2. Monotonic vs. Non-Monotonic?i. A < 0 = Non-Monotonic!

3. If NMUi. Determines 7th order coefficients that relates CT to

HRSG output

ii. Uses regression and Solver add-in to solve for each coefficient

iii. Makes a NMU table relating power to cost for every NMU generator

4. If MUi. Makes a MU table relating power to cost for every

MU generator

Initial Project Work 4/5

5. Consolidationi. Reads in Unit Commitment Tableii. For every hour all dispatchable NMU generators are

consolidated into a master NMU power vs. cost table

iii. For every hour all dispatchable MU generators are consolidated into a master MU power vs. cost table

6. Solution i. For a desired power output, the program loops

through the master MU and NMU tables and finds the least cost solution

ii. Goes into each MU and NMU table and loads each individual power and cost given the master’s power and cost

Initial Project Work 5/5

Client’s Conclusion The algorithm and program are working

correctly and efficiently; however, are extremely confusing to use.

General Solution Approach

The project team will modify the existing software to increase the usability in 4 main areas Main Menu Overall Structure Unit Commitment Output

Main Menu 1/6

Prior Groups’ Main Menu

Main Menu 2/6

Client’s Comments on Existing Menu Extremely Confusing Didn’t understand what output options meant Didn’t understand what format data outside

the menu had to be in Couldn’t find the appropriate places in the

workbook to input data

Main Menu 3/6 New Main Menu

Step by Step like a brief instruction manual Every User Specified Worksheet (data the user

can change) will have a step dedicated to it. Each step will include:

Description of the worksheet How to change the data Acceptable data/data format A hyperlink to the appropriate worksheet A hyperlink to more detail instructions if desired

Output Options Each option will have brief description Scroll Down Lists

Visually Appealing Format Troubleshooting Links

Main Menu 4/6

Structure

Main Menu 5/?

Overall Code Structure 1/5

Client Requests Have the ability to enter a start and end

hour (1-168) Find solutions for only a range of hours

specified

Overall Code Structure 2/5

Dispatching only a range of hours Code must be completely ran once Visual Basic Modifications:

A completely different set of modules will be written (many won’t have to change168)

Any data set that doesn’t change will not be re-read in (stored in memory)

Unit-Commitment and Gen Limits will only be read in for user specified hours

Algorithm will only dispatch user specified hours

Overall Code Structure 3/5

Secondary Menu Will mimic the Main Menu; however common

instructions are more vague Increased Number of User Options

Start/Stop Hours in Scroll Down lists Unit Commitment, Gen Limits, CT vs. HRSG, etc.

data changed? Set existing unit commitment to default?

Opposite Color Scheme

Main Menu 6/?

Main Menu 6/?

Unit Commitment Page 1/9

Client’s Comments on Unit Commitment page Should have statistics on top of page Doesn’t allow changes in current configuration Should be able to reset to default commitment

pattern Should consider a number < 0 or a blank to

mean the unit is not available Should check any changes made to ensure that

generators up and down times are not violated

Unit Commitment Page 2/9

Existing Unit Commitment Page will updated to include the following features:

Calculate the following statistics per hour for a given unit commitment pattern: Maximum generation capability Reserve Generation requirement Foot room Minimum generation requirement

Unit Commitment Page 3/9

Maximum generation capability = The sum of all committed units’ maximum generation capability

Reserve = The maximum generation capability minus the load requirement

Generation requirement = The total required load Foot room = The generation requirement minus the

minimum generation capability Minimum generation capability = The sum of all

committed units’ minimum generation capability

Definitions…

Unit Commitment Page 4/9

The calculations for the statistics will be made by the following: IF statements will be used within the Excel

worksheet The IF statement checks the status of each

generator for the given hour If the generator has a blank or zero, the

generator is considered off/unavailable If the generator has a one then it is considered

on/available and ready for dispatch The IF statement then calculates the statistics

based on the status of the generators

Unit Commitment Page 5/9

The Updated Unit Commitment Page

Unit Commitment Page 6/9

If < 0 or a blank treat as a zero (i.e. not available) The above change will be made within the visual

basic code that loads in the unit commitment data

Master reset button, that loads the default unit commitment pattern from a separate worksheet The reset button is written in a separate macro

which allows a reset of the Unit Commitment table at any given time

Unit Commitment Page 7/9

Unit Commitment Page 8/9

A up and down time checker for any given Unit Commitment pattern The unit commitment checker will be

written in a separate visual basic macro The macro can be ran after each change

made to the unit commitment pattern Any violations of up or down times for the

generators will be noted within the unit commitment table in orange

Unit Commitment Page 9/9

Output Page 1/5

Client’s Comments on Existing Output Sheet Move statistical data to top of output Separate output tables Replace zeros with blanks Remove units that are not committed Insert linear hour

Output Page 2/5

Output Page 3/5

Output Page 4/5

Output Page 5/5

Time Permitting/Future Work

Graphs consisting of the following data: Weekly loading, weekly generation per

generator and weekly generation for the entire system

Weekly fuel usage for each generator and fuel usage for the entire system

Weekly cost of operation for each generator and cost of operation for the entire system

Possible implementation of a faster solution algorithm

Conclusion

The project team will modify a software application that will seek to produce the most economical power distribution, with quick solution times, between monotonically and non-monotonically increasing generators.

Questions?

Excel