The new standard version Engineering Recommendation G99 Issue 1 – Amendment 8 has been published in Sep. 01, 2021.
Minor technical modifications:1. Removal of sentence in Foreword that is out of date.2. Updates to the titles of EREC G5 and EREC P28 in the references and clarification that BS EN 50549 is a suite of documents.3. New references to cyber security guidance documents, a requirement to comply with these in a new clause 9.1.7, new footnote 12 in 14.1.4(f), additional check on compliance in forms A2-1, A2-2, A2-3 and the PGMDs, confirmation in respect of installation compliance in commissioning forms, Form A3, Form B3 and Form C3.4. Amendments to the definitions of Connection Agreement, Droop. MSOL, MRL and Fully Type Tested (see also item 12).5. Clarification on providing validated models, with amendments to 6.3.7, 6.3.8.4(b) and 6.3.8.5.6. A new clause 9.6.2 on customer’s installation island, with an introduction in 9.6.1.7. Modification to 10.2.2, 10.3.8 and Forms A3, B3 and C3 to clarify that the Generating Unit may be tripped, rather than the whole Power Generating Module.8. Relaxation on the output power with falling frequency requirement for CCGT, which aligns with the equivalent Grid Code requirement, in 11.2.3.1(b), 12.2.3.1(b) and 13.2.3.1(b) (and updated Figures).9. Clarification that reactive capability is on the basis of nominal voltage in 12.5.1.10. Review of the use of the terms Minimum Operating Level and Minimum Stable Operating Level, with amendments to 13.2.6.4(b), A.7.2.4.1, B.5.2.5, B.6.2.6, C.8.6.3, C.8.6.5, C.9.5.4 and C.9.5.6.11. A new clause on rapid re-synchronisation requirement, as per RfG Article 15 5 (c), in 13.7.2.12. Modifications for power quality assessment (EREC G5 and P28) and type testing (including removing the word “partial” in the context of type tested), including amendments to 15.3, 22.1 (including table), Forms A2-1, A2-2 and A2-3 and C.9.1.5.13. Allowing for a family approach to type testing in new clauses from 15.6.14. A new clause 15.7 summarising compliance demonstration required for Power Generating Modules in infrequent short-term parallel operating mode.15. Clarification in 20.3.3 that a new EREC G99 application is required where a modification results in an increase in installed capacity over 16 Amps per phase.16. Inclusion of an energy source / energy conversion technologies table at the end of applications forms (A1-1, A1-2), and request for technology type code to be included in application form.17. A request in the notes to include electricity storage capacity (kWh) in the application form, where Electricity Storage devices are part of the installation.18. Modifications to recognise the limitations of small rotating machines to operate stably at low output, including changes to Form A2-1 (new footnotes) and additional guidance in A.7.2.2.4 and A.7.2.5.1.19. Modifications to the forms in Annex A (A2-1, A2-2, A2-3), including:a. Clarifications and additional guidance in the type test compliance verification forms;b. New operating range tests (Test 5 continuous operation) and Test 6 RoCoF withstand in Form A2-1;c. Additional columns in the harmonics test sheet for measurements from all three-phases to be recorded;d. Moved fields for test dates and location to top of voltage fluctuations and flicker test sheet; ande. New requirement to provide a high- level description of the logic interface.20. Modifications to Annex A Form A2-4, including:a. Clarification in the notes at the front of the form that details for other onsite tests should be provided at the end of the form;b. Clarification in the stability tests that confirmation is sought of no trip of the interface protection (similarly in B2-2 and C2-2); andc. Clarification in the test schedule that a trip of the interface protection should trip the appropriate circuit breaker (similarly for B2-2 and C2-2).21. Modifications to the PGMDs, including:a. Clarification that where multiple types of evidence are indicated as being acceptable for demonstrating compliance, the Generator and/or Manufacturer can determine the most appropriate format;b. The addition of “E” for exempt in the key to compliance;c. The addition of space in the PGMD for DNO review date and comment;d. Change the type of evidence requested for Power Quality (voltage fluctuations and flicker and harmonics) from TV (Type Test report) to T (tests) in accordance with modification item 12, and expanded the submission stage to include FONS.e. Removal of the requirement in Form C2-1 Part 1 to undertake simulation studies for synchronous generators in accordance with annex C.7.4;f. The addition of rows to C2-1 Parts 1 and 2 for a number of requirements including C.10 minimum frequency response, 13.7.2 rapid re-synchronisation and C.6 dynamic system monitoring; andg. Removal of a row in C2-1 Part 2 asking for compliance demonstration with 12.2.1 operating range and removal of a duplicate row (13.3).22. Clarification on the provision of modelling equivalents for Customer’s Installations and associated equipment in a new clause B.4.1.3.23. Clarification and drafting improvements to B.4.2.1 (similarly for C.7.3.1).24. Guidance on the minimum fault level that can be assumed in simulation studies in B.4.4.3 (similarly for C.7.5.3).25. Correction of internal cross reference in B.4.5.2 (ii).26. Clarification in C.5.6.1 and C.5.7.1 that the scope is limited to PGMs that are required to comply with relevant parts of the Grid Code.27. Modifications to Annex C.6, including new clauses C.6.2.4 on instrument transformers, C.6.2.5 on overall accuracy, C.6.2.6 on time keeping and the addition of negative and zero sequence parameters in C.6.2.2.2, Table C.6.7 and Table C.6.8 for fault recording.28. Drafting revisions to C.7.3 simulation studies of reactive capability, including new clauses C.7.3.2 and C.7.3.3, to improve clarity.29. Clarification in C.7.5.5 on Grid Code compliant PGMs.30. Clarification in C.7.6.5 and C.7.6.6.31. Clarification in C.8.6.6 and C.9.5.7.32. Corrections to internal cross references in C.9.1.2 and C.9.5.3.33. A small number of minor typographical corrections throughout.
