Technology / Engineering guide
Grid-Following & Grid-Forming Wind Converters
A converter’s grid role describes how it interacts with an electrical reference. It does not, by itself, establish whether a complete wind system can supply an isolated load, restart a dead network or maintain service through every disturbance. Compare the selected equipment and operating conditions.
Define the electrical reference before specifying the mode.
Turn a grid-role label into a capability matrix with clear conditions, boundaries and evidence.
01 / Electrical reference
Distinguish following a reference from establishing one.
Grid-following operation uses an existing network reference for synchronisation.
Grid-following operation uses an existing network reference for synchronisation. Grid-forming operation establishes a voltage and frequency reference through the converter’s controls. The US Department of Energy describes this basic distinction in its inverter overview; it is general background, not evidence of a MARSTON converter capability.
Keep the reference role separate from the source of energy. Wind availability, an electrical reference and a guaranteed supply are different requirements. A device capable of establishing a reference still needs a defined energy source and an applicable operating envelope to support the connected load.
02 / System boundary
Identify the converter being described.
Record whether a claim concerns the generator-side equipment, the network-side converter or an assembled plant.
Record whether a claim concerns the generator-side equipment, the network-side converter or an assembled plant. A machine-side controller regulating generator operation is not automatically the device that establishes the site’s AC reference. Marketing descriptions sometimes combine these separate functions under one system label.
Place the claimed device on the project diagram and identify its firmware, operating configuration and energy interfaces. The microgrid planning guide covers responsibilities across the plant; this comparison concerns the electrical role assigned to an individual converter.
03 / Operating states
Build a state matrix rather than a single checkbox.
List the states actually required: operation beside an established grid, operation beside another reference source, an isolated network, and a de-energised network.
List the states actually required: operation beside an established grid, operation beside another reference source, an isolated network, and a de-energised network. For each, record the proposed reference provider, the participating equipment and the limits of the claimed capability.
Black start, island operation and grid-forming control should have separate entries. Evidence for one does not automatically establish all three. Include the required load conditions and available energy in the matrix, rather than interpreting the word “forming” as an unrestricted continuity promise.
04 / Load response
Compare power demand with the applicable envelope.
A converter’s continuous output, short-duration response and available source energy describe different constraints.
A converter’s continuous output, short-duration response and available source energy describe different constraints. A motor-starting event can require a different assessment from a steady load of the same normal power. Retain the relevant load record when comparing the selected configuration’s evidence.
Ask what the stated response applies to: the converter alone, a test load or the complete proposed installation. An applicable record should identify its boundary, conditions and limitations. Do not turn a laboratory response into a guarantee for an unspecified site network.
05 / Mode changes
Treat transitions as their own engineering requirement.
A project may require movement between operating states, but a list of supported states does not establish the behaviour between them.
A project may require movement between operating states, but a list of supported states does not establish the behaviour between them. Define the intended transition, its initiating condition and the service requirement before reviewing the proposed equipment.
Record who is responsible for system coordination, protection assessment and acceptance of the transition evidence. This is a scope definition, not an operating sequence. Changes to source equipment, configuration or firmware may change the applicability of an earlier assessment.
06 / Capability record
Keep MARSTON enquiries specific to the selected equipment.
The confirmed turbine range uses electric yaw, which positions the nacelle mechanically.
The confirmed turbine range uses electric yaw, which positions the nacelle mechanically. Electric yaw does not establish a grid-forming electrical capability. Specify the actual controller and converter being considered using the equipment selection guide.
For each requested mode, retain a clear status: supported with stated conditions, unsupported, or awaiting evidence. Supply the project diagram, load requirements and reference responsibilities with a technical enquiry. No MARSTON island, black-start or grid-forming functionality is assumed here.
Continue the review with AC & DC Coupling for Wind Hybrid Systems.
Continue the review with 50 Hz & 60 Hz Requirements for Wind Power Projects.
Continue the review with Wind Controller Protocols & Register Maps.
For additional synchronisation terminology, review phase-locked-loop synchronisation concepts; keep this general explanation distinct from verified converter implementation.
Review DC-bus voltage and energy balance, load-step response records and anti-islanding and isolated operation for the proposed operating arrangement.
General background: US Department of Energy: inverter electrical references and grid roles. These references explain industry concepts; they are separate from the applicable MARSTON product and project documents.
Prepare the information for this review.
Use the checklist to organise the project information. Mark unavailable items and retain document references.
| Review item | Information to provide | Purpose |
|---|---|---|
| Reference role | Device providing the AC voltage and frequency reference | Separate electrical roles. |
| Configuration | Converter identity, firmware and operating settings revision | Match the capability claim. |
| State matrix | Required network states and participating energy sources | Expose conditional support. |
| Load envelope | Steady demand, relevant transients and supply continuity needs | Define the assessed service. |
| Evidence scope | Test boundary, conditions, limitations and acceptance owner | Avoid extending a narrow result. |
Engineering questions.
Does grid-forming mean guaranteed off-grid supply?
No. Reference establishment, source energy and complete-system supply performance require separate assessment.
Does a grid-following converter create its own network reference?
Its operation normally follows an existing electrical reference. Confirm the selected device’s documented role.
Is black start the same capability as grid forming?
No. Treat energising a de-energised network as a separate requirement with its own conditions and evidence.
Does electric yaw identify the converter mode?
No. Nacelle positioning and the converter’s electrical reference role are different functions.
Can a converter datasheet establish whole-plant behaviour?
Only within its stated scope. Interactions with other sources and loads need a configuration-specific assessment.
What should be included in a converter-mode enquiry?
The project diagram, reference source, required operating states, load envelope and relevant equipment identities.
Technical enquiry
Bring your project information to the discussion.
A converter’s grid role describes how it interacts with an electrical reference. Share the available information and the equipment scope you want reviewed in a technical quotation.