GC Compliance · EMT & RMS

EMT models & grid-code compliance, done once — done right.

For generators, inverter and OEM manufacturers and developers connecting to the GB system — we build the validated models and run the compliance evidence the connection now legally requires.

PSCAD™ EMT modelsPowerFactory / PSS®E RMSFault ride-throughFFCISSO screeningModel checklist
≥ 1 MWEMT model now mandated
PC.A.9GB Grid Code basis
EMT + RMSBoth domains delivered
ManyCompliance projects delivered
Why this matters now

In GB, an EMT model is no longer optional.

Under the GB Grid Code (PC.A.9, introduced through GC0141), every new grid-connected generator and inverter-based resource above the small-power threshold must provide a validated three-phase EMT model and demonstrate compliance before it can energise — and NESO can require models and evidence from existing owners too. For converter-dominated plant that means proving fault ride-through, fast fault current injection and freedom from sub-synchronous oscillation, not just steady-state behaviour. Miss it and the connection stalls.

Validated EMT model — three-phase, ≤10 µs step, self-initialising, with V&V report
Fault ride-through — the ECP.A.3.5.1 voltage-dip cases, demonstrated and plotted
Fast fault current injection — reactive current measured and plotted at the point of connection
SSO screening — impedance scan + eigenvalue stability across 1–500 Hz
What we deliver

The whole compliance package — under one roof.

We build the models and run every mandated study, structured exactly the way the model checklist expects — so the review passes with the fewest possible iterations.

Compliance coverage · GB Grid Code
Every item is a deliverable we produce in-house — EMT and RMS models, the studies, and the validation reports that close them out.
Fault ride-through & FFCI

Stay connected through the dip — and feed the grid.

The GB Grid Code requires plant to ride through voltage dips along a defined envelope and inject fast fault current while it does. We set up the ECP.A.3.5.1 dip cases in EMT, demonstrate the plant stays above the boundary, and plot the reactive current delivered at the point of connection — the evidence the connection review needs.

Low-voltage ride-through · balanced dip · 140 ms
The terminal voltage stays above the grid-code envelope and recovers cleanly, while fast fault current injection supports the grid during the dip. A marginal tune (toggle) drops below the boundary — a fail we catch before submission.
SSO screening

Catch the oscillation before the grid does.

For inverter-based plant, sub-synchronous oscillation is the risk no fundamental-frequency study reveals. We measure the plant's dq impedance with an active frequency scan, flag every band with a negative real part, and resolve the eigenvalue stability of the grid×plant interaction.

Plant impedance scan · 1–500 Hz
A control-mode resonance sits near 70 Hz; the sub-100 Hz negative-resistance band is exactly where converter–grid interaction must be screened — then confirmed stable by eigenvalue Nyquist.
Proof

We did exactly this on a real ~40 MW battery — full impedance scan, eigenvalue Nyquist and time-domain injection, all stable across the band.

How we get you compliant

Model to approval, in four moves.

01

Build / audit the model

We build your EMT and RMS models — or audit and fix a vendor model — to the structure the checklist demands, encrypted blocks documented.

02

Run the mandated studies

Fault ride-through, FFCI, voltage injection, reactive capability and frequency response — each case set up and plotted for review.

03

SSO screening

Active impedance scan and eigenvalue stability across 1–500 Hz, corroborated by time-domain injection.

04

Validate & submit

Model verification and validation reports — factory, type-test and on-site cross-referencing — packaged for the operator.

Why Velon

We work for the generator, the inverter manufacturer and the developer — the people who have to deliver the model. Same team builds it, studies it and signs off the evidence.

GB Grid Code · PC.A.9 GC0141 · EMT models ECP.A.3.5.1 · FRT FFCI ECP.A.3.7 · frequency response ENTSO-E NC RfG IEEE 2800