Tie Lines between Areas Display

See Also

 

The Tie Lines between Areas Display identifies all area tie lines in the case. Tie lines are not a separate data record that can be created in Simulator, but instead provide a look at all the devices that connect two areas together in the power system model. Tie lines are important because the Area Control algorithms used by Simulator often enforce a constraint which requires that the sum of the flow on the tie lines must equal the net export scheduled by the area (This is often called the ACE equation).

There are several types of devices that can represent tie lines. These include the following:

• Transmission branch (Branch) : a transmission line or transformer that connects two buses that belong to two different areas is a tie line.
• Two-terminal DC transmission lines (DCLine) : a DC transmission line that connects two buses that belong to two different areas is a tie line.
• Multi-terminal DC transmission line (MTDCRecord) : For every multi-terminal DC transmission line that has converters connected to more than one area is a tie line.
• Load (Load): A load can be assigned to a different area than its terminal bus. This is not typical but is sometimes done to model loads at lower voltage level where more than one entity has load that connects to the same power system bus. In such a situation this load represents a tie line.
• Generator (Gen): Similarly to the load, a generator can be assigned to a different area than its terminal bus. Again this is considered a tie line.
• Switched Shunt (Shunt): Similarly to the load, a switched shunt can be assigned to a different area than its terminal bus. Again this is considered a tie line.

Note: The easiest way to see which loads, generators, or switched shunts are assigned in this way is to use this Tie Lines between Areas Display. You can also, however, add separate columns using the display/column options on the Load, Generator or Switched Shunt Case Information Display. For instance, for loads there are columns for Area Num of Bus and Area Num of Load. Normally these are equal, but they will not be for tie line loads.

Note: Be careful when working with cases opened as RAW files in which there are loads that represent tielines. See PTI RAW Transactions due to tie-line load in Simulator Options: File Management for more information.

The Tie Lines between Areas Display is a class of Case Information Display and therefore can be used in a manner consistent with all other case information displays. It has a local menu from which you can print, copy, and modify its information as well as view the information dialog of its associated device type. You can learn more about a particular shunt’s terminal bus by choosing either Quick Power Flow List or Bus View. You can also sort the tie line information by clicking on the heading of the field by which you want to sort. Additionally, you can choose to restrict the information shown by the Tie Lines Display according to the constraints of the area/zone/owner filters.

To call up the Tie Lines between Areas Display, select Aggregation > Tie Lines between Areas from the Model Explorer.

 

The Tie Lines between Areas Display contains the following fields by default:

Tie Type

Indicates type of device that the tie line represents: Branch, Load, Gen, Shunt, MTDCRecord, or DCLine.

Near Area Name, Near Number, Near Name

The Bus Number, Name and Area Name of the bus to which the device is attached. For transmission lines this is the near end of the device.

Far Area Name, Far Number, Far Name

The Bus Number, Name and Area Name of the other end of the device.

Ckt

The circuit ID for transmission lines or DC Lines, the device ID for generators, loads, and switched shunts.

Meter MW and Mvar

The MW and Mvar flow from the point represented by Near Number/Name towards the Far Number/Name. For transmission lines and DC lines the metered point on the line is determined by the Metered End which is stored with the device. For instance on a transmission line, there is a check box for From End Metered which is available on the Branch Options (Edit Mode) dialog. Changing this setting with the device will affect the Meter values slightly.

Status

This is the Open/Closed status of the tie line device.

Lim MVA

For tie lines that represent transmission lines this is the limit (rating) of the device.

MW and Mvar Loss

For tie lines that represent transmission lines this is the MW and Mvar loss across the device.