Create New Areas for Islands

When an area spans multiple electric islands, area MW interchange control may not be possible.

Consider two scenarios shown below. The scenario on the left has Area #1 that spans three islands while Area #2 is contained within a single island. Island C contains both Area #1 and Area #2. Because Area #1 only spans one island that contains more than one area, area interchange control is allowed. When balancing the area interchange in Island C, it can easily be determined what generators will respond. Only those generators in Area #1 in Island C will respond with interchange between Area #2. Internally when the power flow solution is solved, Simulator creates temporary areas for the portion of Area #1 that is in Island A and the portion that is in Island B. This ensures that only those generators that are in Island C will respond to interchange with Area #2. In this scenario, both Area #1 and Area #2 are allowed to be on area interchange control.

The scenario on the right has Area #2 that spans two islands and Area #1 that spans three islands. Because both of the areas are contained in islands that have more than one area, area interchange control is not allowed for both Area #1 and Area #2. Control is not allowed because Simulator does not have enough information to determine in which islands the area transactions are supposed to occur. In this scenario, Simulator will turn off AGC for areas that meet these conditions.

With the Create New Areas for Islands option, permanent areas can be created that match the areas that Simulator creates temporarily while solving the power flow. New areas will get created if an area is on AGC, spans multiple viable islands, and only one of those islands has more than one area in it. An island is considered viable if it has closed non-zero load and an online generator or it has an online generator that is connected to the rest of the system via a DC line. For an area meeting these criteria, new areas will get created for the portion of the area in islands that contain only one area. If an area spans multiple islands and each island contains only a single area, new areas will get created for the islands that have the fewest buses. New areas will only get created if there are generators on AGC or online load in more than one of the islands in which the area has buses. New areas will use the same AGC method as their original area unless that area in on area slack bus control. In that case, the new areas will be on no AGC. New areas will be names with the original area name with the slack bus for the island appended.