Value chain · CLM-0783
In plain terms
Under Great Britain's grid code as the system operator's 2024 guidance describes it, an inverter-based generator must be able to export or import reactive power equal to about a third of its rated output, usually measured where it joins the grid, and the guidance says it should reach 90 per cent of a requested change within one second.
The claim as recorded
The GB Grid Code reactive capability requirement for a Power Park Module, at ECC.6.3.2, has three parts as described by the system operator's compliance guidance: the module must be able to operate with no reactive power transfer from zero to full output within a tolerance of plus or minus 5 per cent of active power output; it must be able to operate over a range of reactive power outputs when producing more than 20 per cent real power, that range being equivalent to 0.95 power factor, or, in the guidance's own restatement, 32.9 per cent MVAr as a proportion of rated power, usually at the Grid Entry Point or User System Entry Point; and 90 per cent of the required change in reactive capability should occur within 1 second (the guidance's own modal verb, a recommendation rather than a "must"), with the capability fully available at all system voltages within 5 per cent of nominal under ECC.6.3.2.4.3.
Scope and limits
This is system operator guidance, not the Grid Code text. The Grid Code itself, and the numeric shape of Figure ECC.6.3.2.4(a) to (c), were NOT obtained when this record was written; the code is now held as SRC-452 and the figures are read at the render in CLM-1107 (2026-09-19). Before any published use, the envelope should be read from the Grid Code Connection Conditions directly. The 32.9 per cent figure is the guidance's own restatement of 0.95 power factor and is consistent with it. THE CLAUSE TEXT IS NOW HELD AS SRC-452, AND IT SHOWS THIS RECORD'S ATTRIBUTION IS TOO COARSE. ESTABLISHED 2026-09-15. ECC.6.3.2 is not one requirement. It is six sub-clauses by plant type, verified by reading the section: .1 Type B Synchronous Power Generating Modules, .2 Type B Power Park Modules, .3 Type C and D Synchronous, .4 Type C and D Power Park Modules with HVDC Equipment and OTSDUW Plant, .5 and .6 offshore configurations. Power Park Modules appear in three of the six and the requirements differ between them. A GW-scale receiver connecting at 275 or 400 kV is an onshore Type D Power Park Module, so ECC.6.3.2.4 governs it and the Type B text does not - and 6.3.2.4 is differently shaped again, covering additional reactive compensation at a Non Embedded Customer connection with a capability requirement pinned above 33 kV. The guidance flattened the clause set and this record inherited the flattening, so the claim above should be read as describing the requirement generically and not as stating what governs any particular plant. AND THE 32.9 PER CENT FIGURE APPEARS NOWHERE IN THE CODE - zero occurrences across 820 pages. It is the guidance's own arithmetic restatement of 0.95 power factor as a proportion of rated MVAr. This record attributes it to the guidance correctly, but it sits in a sentence about a Grid Code requirement and a reader may take it for code text; it is not. Figure ECC.6.3.2.4(c) prints 0.33 as Q/Pmax (read at the render 2026-09-19, CLM-1107): the code's figure carries the same ratio as the guidance's 32.9 per cent, rounded, so the zero count above holds for the text layer and not for the figure. The guidance is based on Grid Code Issue 6 Revision 23 (SRC-240 PDF p.2). In Revision 41 (SRC-452 PDF p.224), ECC.6.3.2.4.3 sets the capability for connections at or below 33 kV against Figure ECC.6.3.2.4(b) and does not carry the 5 per cent voltage wording that the guidance gives under that number.
What it assumes
That the guidance faithfully restates Grid Code ECC.6.3.2, which the guidance itself does not guarantee: it states that "In the event of dispute, the Grid Code and Bilateral Agreement documents will take precedence over these notes."
Where it comes from
Envelope, verbatim, SRC-240 printed p.27 (PDF p.28): "The Grid Code requires a Reactive Capability equivalent to 0.95 power factor usually at the Grid Entry Point or User System Entry Point if Embedded onshore Power Park and at the Offshore Grid Entry Point for Offshore Power Park Modules." Timing, verbatim, printed p.26 (PDF p.27): "ECC.A.7.2.3.1 The speed of response to a step change should be sufficient to deliver 90% of the reactive capability within 1 second"; and the Figure B.1 annotation, printed p.27: "90% of the required change in Reactive Capability should occur within 1 second." Numeric restatement, verbatim, printed p.28 (PDF p.29): "In both cases the dead time is less than 200ms and 90% of the reactive capability (i.e. 90% of 0.95 power factor at full load or 32.9% Mvar as measured as a proportion of rated power at any other load) is achieved in 1 second." Structure of the requirement, verbatim, Appendix A: "In summary, the first part of the requirement is for the Power Park Module to be capable of operating with no reactive power transfer to the public power system (with a tolerance within +/-5% of active power output) from zero power output to full output. The second part of the requirement is for the Power Park Module to be capable of operating with a range of reactive power outputs when producing more than 20% real power..." Voltage range, verbatim: "Grid Code ECC.6.3.2.4.3 states that the reactive power capability must be fully available at all system voltages in the range +/-5% of nominal."
Basis: Grid Code ECC.6.3.2 as described by the system operator's own compliance guidance; requirement applies at the Grid Entry Point or User System Entry Point
Related records
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Cite this
energyaperture.com/c/clm-0783
CLM-0783, Energy Aperture, as of 2024-06.
Connected records
Other published records linked to this one. A list, not a judgement.