Power systems consultancy for studies that don't fit a template.

Electromagnetic transient (EMT) control-interaction studies examine how the fast inner controls of inverter-based resources (IBR) and HVDC converters interact with one another and with the network at sub-cycle timescales. They become necessary when RMS/phasor models can no longer represent the relevant dynamics — typically on weak grids, in converter-dense areas, or where equipment from several vendors connects close together. The work uses detailed, vendor-specific control models in a time-domain EMT environment such as PSCAD/EMTDC.

These are lightly-damped interactions that appear below (or around) the fundamental frequency, often between converter controls and series-compensated or weak networks. We screen for them with impedance-based methods — dq or sequence impedance scans and Nyquist-style stability assessment — and confirm findings with time-domain EMT injection where the screening indicates a risk.

RMS (phasor) studies remain appropriate for most steady-state, load-flow and slower dynamic questions. A move to EMT is warranted when the question involves fast converter controls, harmonic or sub-/super-synchronous interactions, fault ride-through behaviour, or fast fault-current injection — phenomena that RMS models approximate or omit. In practice many projects use RMS for breadth and EMT for the specific cases that govern the result.

Compliance studies are framed by the connecting network operator's requirements and model-quality expectations. We build and validate models to those requirements, document assumptions and scenarios so the work can be reviewed independently, and prepare evidence in the form the operator expects. Specific submission processes vary by operator and project.

Deliverables usually include validated model files, a documented methodology, the scenarios and operating points assessed, result plots, and a written interpretation with engineering recommendations. The exact set depends on the study type and the operator's evidence requirements.