EDC

This Economic Dispatch Calculator utility demonstrates how to calculate a Locational Marginal Price (LMP) using offer curves from more than 300 generating units totaling almost 40,000 MW.  Users can commit or decommit any generator, view and edit any curve in the table, and view any unit offer curve in a graph.  The LMP value is visible at a chosen MW delivery, and unit schedules are identified from the selected column.  The application is zipped with a file size of 406,074 bytes (409,600 on disk).  When downloaded, the zip file opens into 2 files; an executable, and a .csv data file.

Key Benefits

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Users Manual

When EDC starts, it automatically loads the 'Offers.csv' file and populates the EDC Table (upper left), the Commitment List box (upper right), calculates and draws the EDC Graph (lower left 1st tab), and draws the first individual unit offer in the Unit Offer Curve area (lower right 1st tab).

The EDC Table (shown below) is constructed showing the system Locational Marginal Price (LMP) price from low to high in 96 equal slices, each in a table columns.  The LMP value in $/MWh is shown in the 1st row.  The 2nd row is the total amount of generation that would be available if all units were at their limit or at their economic point for each LMP price.  All other rows show a generating unit each with unit number and name down the left 2 columns; every unit occupies 1 row.

If a unit is committed and therefore on-line, it will show the expected economic unit schedule value for every LMP value.  When a unit is loaded at minimum, the displayed value background color is green; if the unit is neither fully unloaded nor fully loaded at the given LMP, it shows blue; if the unit is fully loaded, the value is red.  If the unit is offline, or decommitted, the row is blank.  

By scrolling the table horizontally, the range of operation of each unit can be readily observed as it progresses from minimum green to dispatchable blue and fully loaded red.  For example, study the picture above.  In it, you will see that unit name 'C1003' is unloaded at a minimum generation of 25.00MW for all LMP values less than $26.24, and ranges between 36.95MW at $26.92 to 56.94MW at $31.62 until it is fully loaded to 60.00MW at all LMP values greater than $32.30.

By scrolling the table vertically, the unit schedule for each unit for a given LMP value can be easily seen.  For example, from the picture above, you can see that when the LMP is $28.93, the generation amount for these generators should be: C1000 = 67.38MW, C1001 = 10.00MW, C1002 = 279.00MW, C1003 = 44.48MW, etc.

The MW value for every generating unit in each cell of the table is solved either via interpolation or block depending on the state in the Unit Record from that unit's offer.  In the above picture, Units C1000, C1002 and C1004 are Slope types while C1005 is Block type.  Slope type units have a raising price per raising MW value by interpolation while Block types have flat prices until the next step is achieved.

 (shown in the Offers Table and Unit Record [lower left 2nd tab]).  The second row in the EDC Table, the total generation, is the sum of all individual unit schedules, solved by adding the generation values of every unit in the column below.

The EDC Graph (shown below) is the LMP from the 1st row of the EDC Table plotted vertically compared to the Total Generation of the 2nd row plotted horizontally.  The graph can be shown in Bar, Line, and/or Balloon format by selecting options from the popup menu.

The Bar type display readily gives the observer an indication of the flatness of the LMP curve.  For example, between 8000 and 13000 MWs, the price slopes upward ever so slightly.  But it takes a dramatic upward swing between 13500 and 145000 MWs.

When units are added or removed from service (by checking the box in the List View box, upper right), the curve is redrawn with the new parameters.  It is very informative to see the impact in both capacity and LMP price by the status of a large unit.  Best observed when viewing the Line format, notice the impact of adding a 590MW unit in the following graph--that of shifting the dramatic LMP price rise out 590MW:

The Commitment List (shown below) contains all generators for which offers have been received and by default are sorted alphabetically by name.  The sorting parameters can be changed by clicking column headings.  Ascending or descending options can also be chosen from the pushbuttons at the top.

Every Generating unit is shown--those that are checked are committed online.  To commit a unit, simply click its box to be checked.  To decommit a unit, uncheck its box.  When a unit commitment status is changed, the Lambda Table is immediately updated with new LMPs and Total Generation and a new graph is created..  

Along with the name, the Zone, Min MW, Max MW, Min $ and Max $ are shown.  When the mouse is hovered over or clicked on a row, a curve is drawn in the Unit Offer Curve space (lower right) as shown in a following picture.  Likewise, the highlighted row is drawn in red in the Offers Table (lower left, 2nd tab) to aid the user in making edits to the table if desired.

The Unit Offer Curve graph (shown below) is drawn for a unit when the mouse hovers over, or clicks on a unit shown in the List View.  This feature simply makes it easy to view individual offer curves before committing (or decommitting) them.

The space between the maximum offer and the Unit Hi Limit (seen in the graph) means that generation higher than the curve will be priced at the maximum offer amount.

Also available in this graph via popup menu is the ability to view Bar, Line, and/or Balloon drawings.  This example shows all 3 drawn.  Other popup menu items allow either or both price to reference from $0 and generation from 0 MW.

The Offers Table tab (shown below) contains all information from an offer, which for this demonstration application is Unit Name, Market Zone, Low Limit, High Limit, Slope or Block, and 6 MW/Price pairs.  The currently highlighted unit in the Commitment List is highlighted in red in this table and the values presented in the record view.  You may make any edit to the information show provided you do them in the record fields.  However, be warned that no validation of any kind is performed on these edits--placing erroneous information here may cause the EDC calculator to malfunction.  Once making modifications to an offer, the user may save them back to the 'Offers.csv' file by clicking the 'Save Offer DB' pushbutton.  

Note that the only way to select which unit offer to view is by highlighting that unit in the Commitment List, and the only way to edit it is through the Unit Record panel in the Offers Table tab.

The Commit Filter tab (shown below) allows the user the ability to commit all (All On), commit none (All Off), or commit any that pass the entered criteria (On/Off).  The On/Off selection will allow the user to select any that are above a minimum MW value, below a maximum MW value, above a minimum price, below a maximum price, and belong to one of the check-box-selected fuel categories.

As soon as one of the buttons is pressed, the Lambda EDC table updates and the Lambda curve is drawn.

If desired, the user may generate a "Lambda Output.csv" file showing the Unit Schedule for every on-line unit from minimum to maximum price by clicking on the Export LMP csv file button.

Training Materials Available

If you are planning a training seminar, webinar, or just an educational meeting in your office, we are willing to make modifications and customizations to fit your needs.  A companion application is under development that will allow load zones to bid and generator owners of offer in a simulation game.  When the game is completed, check at this site for more information.  If you are in a hurry, email David L. Tuck.