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Running power flow analysis

This guide shows you how to run power flow analysis on your single-line diagram and view the results.

Before you start

Ensure your diagram meets the requirements:

  • At least one power source (utility feed or generator) connected to the system
  • All components have valid electrical parameters (voltages, power ratings, impedances)
  • Every bus drawn with a path to a power source. A bus that only an open device, an open wire or an out-of-service component cuts off is fine: it shows No supply and the rest solves.
  • Cable lengths and types specified
  • Load values entered for all loads and motors

Running the analysis

  1. Open your project in the SLD editor.
  2. Verify that all components connect to a power source.
  3. Click Load Flow in the header.
  4. The analysis runs on the scenario selected in the header. A badge under the button shows it is running.
  5. Results appear automatically on the canvas as annotations.

When you start the analysis, EKX checks the network before running. The validation dialog explains any issues that need review.

Auto-show results feature

After a successful power flow calculation, result annotations automatically display on your diagram. The system:

  • Enables the results visibility toggle
  • Shows voltage annotations on buses
  • Displays current and loading on cables
  • Shows transformer loading and currents
  • Displays load terminal voltages and power draw

You don't need to manually enable results - they appear automatically after the first successful run.

Viewing results on canvas

Power flow results appear as annotations attached to components:

Bus annotations show:

  • Voltage magnitude (0.98 pu or 470 V depending on unit system)
  • Voltage angle in degrees
  • Color-coded severity (green, yellow, or red)

Cable annotations show:

  • Current magnitude in kA or A
  • Loading percentage (current / rated current × 100)
  • Color indicates loading severity

Transformer annotations show:

  • Loading percentage
  • HV side current (primary winding)
  • LV side current (secondary winding)

Load annotations show:

  • Active power consumption (MW or kW)
  • Reactive power consumption (MVAR or kVAR)
  • Terminal voltage (actual voltage at load connection point)

Toggling annotations on and off

To control result visibility:

  1. Click the eye button in the canvas controls (top-left corner of the canvas) to hide or show all results.
  2. Click the arrow below it (Result Display Options) to show or hide load flow results alone.

Hiding annotations clears the canvas for easier editing. Showing them again displays the same results until you rerun the analysis.

Results are saved with the project. When you reopen it, reload the page, or go back to it, the last results show again. Results from before a later diagram change show greyed until you rerun the analysis.

Switching between unit systems

You can view results in two unit systems:

Per-unit system:

  • Voltages shown as fraction of nominal (0.95 pu to 1.05 pu)
  • Powers in MW and MVAR
  • Best for analyzing voltage deviations

Engineering units:

  • Voltages shown in actual kV or V
  • Powers in kW and kVAR
  • Best for equipment verification

To switch:

  1. Click the gear icon (Diagram Settings) in the header and open Project Settings.
  2. Under Voltage display, select Per-Unit, Engineering, or % Drop.
  3. Annotations update immediately.

Rerunning after changes

While load flow results are shown on the canvas, they rerun by themselves after any change that affects them: a property edit, a new or deleted component, a changed connection, or an accepted sizing change. Updating load flow... shows in the header while the new results are calculated, and the earlier results stay on screen until they are replaced. Results that were already stale when you open the project rerun the same way.

When short circuit results are also shown, load flow reruns first and short circuit follows.

Results stay gray, with Results stale in the header, only when they cannot refresh by themselves:

  • The automatic rerun failed. Hover over Results stale to see why, for example a blank required value. The next change that affects the results tries again, or click Load Flow.
  • You can view the project but not edit it.

Hidden results do not rerun. Show them again to refresh them.

Handling calculation failures

If power flow fails to converge, you see an error message explaining the issue. Common failures:

  • No source: Connect a utility feed or generator to the network.
  • A bus with no connection to any source: The message names the bus. Connect it or delete it. A bus cut off only by an open device, an open wire or an out-of-service component is not a failure; it shows No supply.
  • Missing parameters: Check that all components have required electrical data.
  • Numerical issues: Verify load and generation values are reasonable.

See Troubleshooting convergence for detailed solutions)

Related topics

On this page

Before you startRunning the analysisAuto-show results featureViewing results on canvasToggling annotations on and offSwitching between unit systemsRerunning after changesHandling calculation failuresRelated topics