Consultancy · study

Fault ride-through (FRT) studies

Fault ride-through (FRT) defines how a generating unit must stay connected and support the network through and after a voltage disturbance. An FRT study verifies, usually in EMT, that the plant rides through the required voltage-time profile and injects reactive current correctly during the fault.

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When it's needed

When this study is needed.

  • A grid code requires demonstration of low- (and often high-) voltage ride-through for the connection.
  • The plant is inverter-based, where ride-through depends on control settings rather than machine physics.
  • Protection or control settings have changed and compliance must be re-confirmed.
  • Site behaviour during a real event needs to be reconciled with the compliance case.
Method

How we approach it.

  1. Identify the applicable ride-through profile and reactive-current requirements from the grid code.
  2. Apply the specified fault types and durations at the connection point in the EMT model.
  3. Check voltage recovery, the magnitude and timing of fast fault-current / reactive-current injection, and continued connection.
  4. Test the corners: deepest voltage dip, longest duration, weakest grid, and relevant dispatch points.
  5. Document pass/fail against each criterion with annotated waveforms.
Software

Tools we use.

  • PSCAD / EMTDC for time-domain fault simulation
  • Vendor IBR / HVDC control models
  • RMS tools (PowerFactory, PSS®E) for context and screening
Scenarios

Scenarios & operating points.

  • Symmetrical and asymmetrical faults across the required voltage-dip profile
  • Minimum and maximum grid strength at the connection point
  • Different active-power dispatch levels
  • High-voltage ride-through where the code requires it
Deliverables

What you receive.

  • FRT compliance report mapped to each grid-code clause
  • Annotated voltage and current waveforms per case
  • Statement of control settings used and any dependencies
  • Validated model files supporting the result
Quality & validation

Evidence that stands up to review.

Results are tied directly to the code's acceptance criteria, clause by clause, with the governing (worst-case) scenarios identified rather than a single nominal run. Assumptions and settings are documented for independent review.

Selected work

Comparable experience.

Case-study write-ups for this service are in preparation. To discuss directly relevant project experience, brief us — we can talk it through, under NDA where appropriate.

FAQ

Questions engineers ask.

Is FRT the same as fast fault-current injection?
They're related but distinct. FRT is the requirement to stay connected through a voltage profile; fast fault-current injection (FFCI) is the reactive/active current the plant must supply during the dip. An FRT study typically checks both.
Why test the weakest grid case?
Ride-through and current injection are hardest to achieve when the grid is weak, because the same current produces larger voltage excursions. The weak-grid corner usually governs compliance.
Do FRT settings interact with stability?
Yes — aggressive ride-through and current-injection tuning can affect small-signal and control-interaction behaviour, which is why FRT is often assessed alongside stability and SSO screening.
Next step

Brief us on a study.

Send a one-paragraph scope — the system, the codes that apply, and the question you need answered. We typically reply within two working days.

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Related: Consultancy hub · BESS & inverter compliance · EMT & grid-code compliance · SSO / impedance studies

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