CurveFit

CurveFit is a program initially designed to assist a results-engineer develop suitable operating data points that accurately model the heat-rate performance of a thermal electric generator. The data points would be given to dispatch where they would be refined, verified, and keyed into an Energy Management System (EMS) computer for use in Automatic Generation Control (AGC) and Unit Commitment programs. The application is zipped with a file size of 339,968 bytes.  When downloaded, the zip file opens into 8 files; an executable, an initialization, a help file, and several example data files.

Key Benefits

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Users Manual

Being a new power plant results engineer employee, Hank knew CurveFit would enable him to give accurate generator performance information to the dispatch office.  After acquiring the free software, he entered 'name-plate' information using the Entry Wizard.

Hank gathered test information from direct measurements of his generator of MWhs out and MMBtu of fuel in.  After entering 20 sets of MWh versus MMBtu values, he clicked the 'Calc Ave Btu/KWh' button, which solved for Ave Btu/KWh and Incremental Btu/KWh. 

If Hank had access to polynomial coefficients, he could have entered those numbers, and pressing the 'Build from Coef' on the Input/Output panel, it would have created the MWh and MMBtu columns from that source.

From the Coefficient Polynomials panel, Hank can select the polynomial order, and decide to view it directly or in powers of 10.

No matter how the information gets loaded into the Input/Output table, Hank wishes to create an offer table suitable to be sent to his ISO.  From the Piecewise Linear Curve panel, Hank clicks the 'Build from I/O' button.  All needed columns of data will be created.  Hank can change the number of rows, or segments, wanted using the 'Insert' and 'Delete' rows buttons.

Observing the table, Hank sees that the 'MWh' and '$Inc' columns are perfectly suitable as the basis for his offer submission. 

Before wrapping up work and heading to lunch, Hank clicks each of the graphing buttons to observe the curves:

Input/Output values are drawn from Input/Output, Coefficient, and Piecewise Linear tables.  Taking the first derivative of this number set, the incremental and average performance curves are shown:

It is informative and convenient to compare curves from all 3 sources superimposed.

Converting Btu/KWh consumption to a price curve using Fuel Cost from the name-plate data is a simple matter of mathematics.

Hank sends the information to the dispatch center.  An offer is submitted to the ISO, and Hank goes to lunch at Wendy's (we know Hank is a cheap guy, because he uses this free software) and he lives happily ever after.