Build your network

This chapter shows you how to draw a network as a single-line diagram. You place busbars, join them with lines and transformers, connect sources and loads, and arrange the result. The diagram is also the model. Every calculation uses what you draw and the data you enter for it.

If you already have a model in another tool, import it instead. PowerStudio lays the diagram out for you.

Before you start

Decide the voltage levels of your network and where its sources are. You need at least 1 source in each connected part of the network:

an External grid, which stands for the upstream network and holds the voltage
a Machine in Reference mode, which holds the voltage angle and balances the system

A part of the network without either is left out of the load flow. If it has machines only, PowerStudio picks the largest as the reference and warns you.

Drawing gives each element typical values. You then replace them with your own data. Enter element data shows you how.

Start a network

Go to the File tab.
On the New page, select Empty network.

The network starts with default study settings. PowerStudio saves your work in this browser as you go. The title bar shows Saved when your last change is stored.

To name the network, edit its name in the title bar. To set its base power and frequency, select an empty part of the diagram. The inspector then shows the network's Name, Base power, Frequency and Description. The base power is the MVA that per unit values refer to. The frequency is 50 Hz or 60 Hz.

Choose a tool

Choose a tool on the Insert tab, or press its key. Press the key again to go back to the Select tool. Press Escape to end a tool.

Tool	Key	What it does
Busbar	B	Places a busbar where you select.
Line	L	Places a line between 2 busbars of the same voltage. Select 1 busbar, then the other.
Transformer	T	Places a 2-winding transformer between 2 voltage levels. Select 1 busbar, then the other.
Machine	G	Connects a synchronous machine to the busbar you select. Its short-circuit source can also make it a network feeder or a converter-fed unit.
External grid	E	Connects the equivalent of the upstream network. It holds the voltage and balances the system.
Load	D	Connects a load to the busbar you select.
Shunt	C	Connects a capacitor bank or a reactor to the busbar you select.
Select	V	Moves and selects elements.
Pan	H	Moves the view. You can also hold Space.

The status bar and the hint over the diagram tell you what the current tool expects next.

Place busbars

A busbar is a point where elements connect. In the model, it is a node.

On the Insert tab, select Busbar, or press B.
Select a point on the diagram. A busbar appears there.
Repeat for each busbar you need.
Press Escape to end the tool.

A new busbar is 120 units long and has a nominal voltage of 20 kV. To change the voltage:

Select the busbar.
In the inspector, under Basic data, change Nominal voltage.
Press Enter.

To lengthen or shorten a busbar, drag one of its ends. The other end stays where it is. You can also change Bar length under Diagram in the inspector.

Join busbars with lines and transformers

Select Line on the Insert tab, or press L.
Select the first busbar.
Select the second busbar.

The 2 busbars must have the same nominal voltage. If they differ, PowerStudio shows a Different voltages warning. Select Use transformer in the warning to place a transformer instead.

For a transformer, select Transformer or press T, then select the 2 busbars in turn. The busbar with the higher voltage becomes the HV side. The transformer takes its rated voltages from the busbars.

PowerStudio gives a new line typical data for its voltage: a 3 km cable at 36 kV and below, or a 20 km overhead line above that. A new transformer gets typical ratings for its voltage levels. Replace both with your own data.

To move 1 end of a line or transformer to another busbar, drag that end onto the new busbar.

Connect sources, loads and shunts

Select Machine, External grid, Load or Shunt on the Insert tab.
Select the busbar to connect it to.

The element appears on the side of the busbar where you selected. The tool stays active, so you can add more. Press Escape to end it.

The first machine you add to a network without an external grid is a Reference machine. Later machines are PV machines, which hold their active power and voltage.

To move a connection along its busbar, drag it. To move it to the other side, drag it across the busbar, or select it and press X (Flip side).

Snap elements into line

Elements line up as you place or drag them.

A busbar you drag lines up with the busbars on screen. When its start, centre or end comes within a few pixels of another busbar's, it snaps there. A dashed guide shows the line.
Otherwise, a busbar lands on the grid. Choose the step on the View tab: Grid 10, Grid 20 or Grid 40. The dots follow it.
A connection you drag along its busbar snaps to the busbar's centre.
The end of a branch snaps into line with its other end, so the route runs straight.

Hold Alt to place anything freely. While you drag, the status bar shows how far you have moved, or the length of the busbar.

Select elements

To select 1 element, select it. To add to the selection, hold Shift or Ctrl and select more.
To select by area, drag a marquee over empty space. Dragging to the right selects what lies wholly inside it. Dragging to the left selects whatever it touches, and draws a dashed outline.
Where elements lie on top of each other, select again at the same spot to pick the one beneath.
To select by name, press Ctrl+K and type, or select the element in the model tree.
To select everything, press Ctrl+A (Select all on the Home tab).

The Arrange tab adds selections based on the current one:

Select connected adds a busbar's connections, or an element's busbars.
Select same kind selects every element of the kinds selected.
Select voltage level selects every element at the voltage levels of the selection.

Arrange busbars and connections

The Arrange tab tidies the diagram. Each command is 1 step that you can undo. You can also right-click a selection for the commands that apply.

Group	Command	What it does
Align	Align left, Align centres, Align right, Align top, Align middles, Align bottom	Lines the busbars up with the first one you selected.
Spacing	Distribute horizontally, Distribute vertically	Spaces 3 or more busbars evenly.
Spacing	Same length	Gives the selected busbars the first one's length.
Turn	Rotate (R)	Turns busbars between horizontal and vertical.
Turn	Flip side (X)	Moves machines, loads and shunts to the other side of their busbar.
Connections	Spread connections	Spaces the connections of the selected busbars evenly.
Connections	Lay out diagram	Lays the whole diagram out again from the network's topology.

Shape the route of a line or transformer

A line or transformer has an automatic route that follows its busbars wherever they go. The inspector's Diagram group says which kind of route a branch has.

To shape a route by hand:

Select the branch. A handle appears on each segment.
Drag a segment across itself.

Where a segment meets a busbar, it gets a jog, so the route still leaves the busbar at right angles. To remove a jog, double-click its handle. A route you shaped keeps its bends and stays square to its busbars when they move.

To move the middle segment of an automatic route, select the branch and drag that segment. The route stays automatic and its Route offset changes.

On the Arrange tab:

Route around obstacles finds, for each selected branch, the route with the fewest bends that crosses no busbar or symbol.
Straighten route makes the routes automatic again.

A line or transformer you draw is routed around a busbar or symbol from the start if its automatic route would cross one.

Find your way around a large diagram

Fit (F) shows the whole diagram. Zoom to selection (Shift+F) fits the selection in the window.
Zoom in and Zoom out are on the View tab.
Pan (H), or holding Space, moves the view.
Overview map (M, on the View tab) draws the whole network with the view as a rectangle. Select or drag in it to move the view there. The map shows by default from 200 busbars.

Control the labels

PowerStudio places names and result boxes so that none covers another. A label moves along its line or busbar if its usual place is taken. If nothing nearby is free, it moves further and a thin leader line joins it to its element.

Use the View tab to choose what shows:

Result boxes, Names and Line names switch each kind of label on or off.
Disentangle labels (Shift+L) switches the automatic placing on or off. Off puts every label in its fixed place.
Colour by results and Colour by voltage level choose how elements are coloured.

To place a label yourself, drag it. It stays there, relative to its element, when the element moves. The inspector's Diagram group says how many labels you placed by hand. To go back to automatic placing, select Reset label positions on the View tab, or right-click a label.

Cut, copy, paste and delete

Copy (Ctrl+C), Cut (Ctrl+X), Paste (Ctrl+V) and Duplicate (Ctrl+D) are on the Home tab.
Copying a busbar copies the machines, loads and shunts connected to it. A line or transformer copies only if both its busbars are selected.
Pasted busbars appear 40 units down and to the right, and their names end in "(copy)".
Delete removes the selection. Deleting a busbar also deletes everything connected to it.
The arrow keys move the selection 1 grid step. With Shift, they move it 5 steps.
Switch in or out of service (Shift+O) switches the selected elements. A busbar cannot be switched out.

Undo and redo

Every change is 1 step you can undo. Press Ctrl+Z to undo and Ctrl+Shift+Z to redo. Press Escape during a drag to put everything back as it was.

Check your network before you calculate

Before you run a study, check that:

every busbar has at least 1 line, transformer or element connected
every line joins 2 busbars of the same voltage
each connected part has an External grid or a Reference machine
you replaced the typical values with your own data

Then enter your element data and run a load flow.