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Fault ride-through (FRT) studies

Fault ride-through is the rule that a plant stays connected and supports the grid through a voltage dip. We show in EMT that your plant rides through the required voltage-time profile and injects reactive current the way the code asks.

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Ride-through · voltage and currentIllustrative
00.51V (pu)00.511.501t (s)Iq (pu)fault
Voltage at the connection point against the ride-through envelope, and the reactive current the plant injects.
When it's needed

When you need it.

  1. The grid code asks for proof of low-voltage, and often high-voltage, ride-through.
  2. The plant is converter-based, so ride-through depends on control settings.
  3. Protection or control settings changed and compliance needs confirming again.
  4. Behaviour during a real event has to be squared with the compliance file.
Method

How we run it.

  1. 01

    Define

    Take the ride-through profile and current rules from the grid code.

  2. 02

    Apply

    Apply the specified fault types and durations at the connection point.

  3. 03

    Check

    Check voltage recovery, fast fault current, timing and staying connected.

  4. 04

    Edges

    Test the edges: deepest dip, longest fault, weakest grid.

  5. 05

    Record

    Pass or fail against each criterion, with annotated waveforms.

Tools and scenarios

What we use and what we test.

Tools

  • PSCAD / EMTDCFault simulation
  • Vendor control modelsIBR and HVDC
  • PowerFactory · PSS®ERMS screening

Scenarios we run

  • Symmetrical and asymmetrical faults across the required 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 get.

  • ReportFRT compliance report mapped to each grid-code clause
  • WaveformsAnnotated voltage and current waveforms for every case
  • SettingsThe control settings used, and anything they depend on
  • ModelValidated model files behind the result

How we check it

Results map clause by clause to the code's acceptance criteria, and we name the worst-case scenarios rather than one nominal run. Assumptions and settings are written down for independent review.

Selected work

Related case studies.

Case 03 · SSO and compliance40 MW battery: SSO screening and NESO complianceImpedance scan, Nyquist, voltage injection, FRT and FFCI from one model.Case 02 · EMT modellingGenerator EMT model checked against site measurementsA full PSCAD model with excitation, stabiliser and protection, validated on site.
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

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Related: Consultancy hub · 40 MW battery case study · EMT & grid-code compliance · SSO / impedance studies