See Also
The Info/Interchange Tab serves as an accounting sheet for flows into and out of an area. It houses the following controls:
Load, Generation, Shunts, Losses, Interchange
These read-only fields express the total real and reactive load, generation, shunt compensation, losses, and interchange for the area.
Interchange
Interchange in MW between the area and all other areas (exporting power is positive). To prescribe an interchange with a specific area, simply enter the amount of power in MW to export to that area in the MW Export column. To specify an import, enter a negative value. If the recipient of the power is unknown, you may enter the net total in the Unspecified MW Interchange field found above the list of transactions. The net value of the MW imports and exports is displayed in Transaction MW.
Check the box Only Show Areas with Nonzero Interchange to display only those areas whose interchange is different from zero.
By default, one interchange record is initially defined between each area. The total interchange between two areas can be managed using this single record. However, it is possible to define multiple interchange records between the same areas. To do so, you can right-click in the interchange table and select Insert from the local menu. This will open the Transaction Dialog, which will allow you to insert a new transaction. Transactions between the same two areas must have unique transaction IDs. Once you have multiple transactions defined between the same two areas, you can choose which transactions are enabled using the Enabled property in the Base Interchange table. This field is a toggleable field, meaning you can double-click in the field to toggle its value.
The total interchange defined for an area will be displayed in the summary field labeled Interchange in the area summary totals on the left side of the page.
AGC Tolerance
The MW tolerance is used in enforcing area interchange. When the absolute value of the ACE is less than this value, Simulator considers the area interchange constraint to be satisfied.
ACE (Area Control Error)
Current area control error (ACE) for the area in MW. Note that, when the constant frequency model is used, ACE = area generation - area load - area losses - scheduled area interchange - area shunt MW.
Area Has Multiple Islands
This is an informational field that cannot be changed. If checked, then Simulator has detected that the area has devices in separate electrical islands in the system. This is important because it is sometimes impossible for an area using some form of generation control (AGC) to solve for the generation dispatch in the entire area (Area Generation = Area Load + Area Losses + Area Interchange + Area Shunt MW) when the area is not entirely within the same electrical island. If Simulator is unable to solve for areas that span multiple islands, the AGC status of the area will automatically be set to "Off AGC" and a warning message will be written to the Simulator message log.