DIgSILENT

Knowledge base

What do "unsupplied areas" and "isolated areas" mean?

Category:
 
Load Flow
Answer

An "isolated area" is a node or a group of nodes which are connected to each other. Each isolated area is assigned to an index (Parameter Name b:ipat) and needs a load-flow reference (slack) of its own. Besides that, an isolated generator or an isolated external grid forms its own area.

An "unsupplied area" are elements or groups of elements which are not supplied (i.e. voltages and current are zero).

An isolated area refers to nodes, while unsupplied areas refer to edge elements.

In the attached example you can see 3 different configurations:
• A: No isolated area (all nodes are connected), one unsupplied area (load is not supplied)
• B: 2 isolated areas (busbars are separated), 1 unsupplied area (load is not supplied)
• C: 2 isolated areas (busbars are separated), no unsupplied areas

To identify areas within a network you have two different possibilities:
1. If a network diagram is drawn, you may colour it by "Isolated Areas".
2. You may use the browser view "objects relevant for the calculation". For busbars and terminals open the "Flexible Data Page" and add the variable "b:ipat". This variable describes the index of the isolated area. For external grids and generators select the "Flexible Data Page" and add the variable "r:bus1:b:ipat"

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