Capacitance at To side (Cdc 2) in microF.

Max Current: Current rating in Amps.

The DC Line Properties dialog also shows the DC power and current entering the line from each bus.

9.19 DC Breaker

DC breakers are connected between a pair of DC buses (or a DC bus and ground). They are represented by a switch symbol in the Bus Tree and diagrams.

The attributes of each DC breaker, shown in the DC Breaker Properties dialog, are the following:

DC Bus 1: Name of the “From” DC bus (8 character long). DC Bus 2: Name of the “To” DC bus (8 character long).

To move a DC breaker from one DC bus to another bus, click on the browse button (. . .) beside the DC bus name to open the Set DC Bus dialog, select the destination bus in that dialog and click the OK button. To connect the breaker to ground, in the Set DC Bus dialog, click the “Set to Ground” button instead of selecting a DC bus.

ID (Circuit no): Circuit number to distinguish parallel DC breakers.

Status: Breaker status which can be set to one of the following:

 Closed

9.20 Area

Buses belong to control areas. Each area can have a designated Slack bus. With Area Interchange control, the generation at the slack bus is adjusted by the powerflow solution to keep the power export from the area at the desired value. In this adjustment, the generator MW limits can be respected or ignored.

The attributes of each area, shown in the Area Properties dialog, are the following:

Number: Unique integer number used to identify the area.

Name: Unique name (up to 16 characters), used to identify the area.

Slack bus: Area slack bus (for area interchange control). This bus must be a generator bus in this area. In the areas containing a swing bus, that swing bus must be specified as the area slack bus.

To change the slack bus, click on the browse button (. . .) beside the bus number/name to open the Set Slack Bus dialog, select a bus in that dialog and click the OK button.

Control Area Export: Control flag, which can be set to one of the following:

 Enabled

 Disabled

Power of Enabled slack generators will be adjusted in powerflow solution if the Area Interchange solution parameter is set. Power of Disabled slack generators will not be adjusted by Area Interchange control.

Limit Slack Gen.: Flag for adjustment by Area Interchange control, which can be set to one of the following:

 Yes (to keep the slack generation within its limit)

 No (to ignore the slack generation limits)

Desired MW Export: Desired (scheduled) real power export, in MW, from the area.

Export Tolerance: Tolerance, in MW, for control of export at its desired value.

9.21 Zone

Buses also belong to zones. Zones can cross area boundaries (buses of one zone may belong to more than one area and vice-versa). The attributes of each zone are:

Number: Unique integer number used to identify the zone.

Name: Unique name (up to 16 characters), used to identify the zone.

9.22 Owner

Number: Unique integer number used to identify the owner.

Name: Unique name (up to 16 characters), used to identify the owner.

9.23 Sectional Branch

A Sectional Branch consists of series connected lines, series compensators, and/or at most one 2-winding transformer or static tap changer/phase regulator. A sectional branch is represented by a line with three sections in the Bus Tree and diagrams.

The Sectional Branch data table shows the following information for the sectional branches:

From-Bus: Terminal bus at the “From” end. To-Bus: Terminal bus at the “To” end.

To connect the branch to a different From or To bus, click on the browse button (. . .) beside the bus number/name to open the Set AC Bus dialog, select the new bus in that dialog and click the OK button.

ID: 8 character identifier.

Status: In-service or Out-of-service status.

All sections of a sectional branch must have the same From-bus, To-bus (in the same order) and ID, and consecutive Section numbers (1, 2, . . .) starting from 1 for the section at the From-bus. Note that a sectional branch cannot have more than one fixed or adjustable transformer or static tap changer/phase regulator.

The sections of sectional branches are included with regular branches in the Line, Transformer and other tables and have properties similar to regular branches. In those tables and property dialogs, sections of sectional branches have a non-zero Section number. Changing the From-bus, To-bus, ID or Status of a section in those tables and property dialogs will apply the same change to all sections.

The connection points of sections (mid-buses) are not represented explicitly in the powerflow data, but their voltages are included in some of the reports.

After selecting a row of Sectional Branch table (click on the row), Property Dialog of the Edit menu (or double click on the row) opens the Sectional Branch Dialog where you can view, add, remove, modify and rearrange the sections of that branch. See Sectional Branch Dialog on how to add sections to a non-sectional branch.

9.24 Case Description

The Case Description dialog which opens by double clicking Case Description under PowerFlow Data in the Workspace, shows the Title as well as the number of elements (buses, generators, etc) in the powerflow data and the date and time of its creation (or modification).

The Title has three lines of text, up to 80 characters each. To modify the title, simply click on each line and delete and insert text.