Section 6 Other installations design evaluation

6.1.1 This is an optional certification module in IEC 61400-22 Wind turbines – Part 22: Conformity testing and certification and IECRE OD-502 Project Certification Scheme; evaluation should be undertaken for ‘other installations’ as directed by the applicant. The scope of the design evaluation should be developed by the certification body and agreed with the applicant before commencing any evaluation.

6.1.2 The term ‘other installations’ includes any type of installation other than the WT and WT support structure that forms part of the wind farm project, such as collector hubs, electrical substations and transformer platforms. It can also include cables, i-tubes, j-tubes or any other part of the project infrastructure.

6.1.3 The purpose of this evaluation is to confirm that the design of the ‘other installation’ complies with the design basis. If the ‘other installation’ is not addressed in the project design basis (evaluated as part of the earlier module, Ch 2, 2 Design basis evaluation) the design evaluation undertaken as part of this module can be completed using codes and standards specified by the applicant and agreed by the certification body.

6.2.1 The documentation to be provided by the applicant will depend on the ‘other installation’ under consideration, to be defined by LR on a case-by-case basis.

6.2.2 For a structure (e.g. substation) the documentation expected to be provided by the applicant is similar to that described in Ch 2, 5 Site-specific support structure design evaluation.

6.3.1 LR’s evaluation for structures according to this module will be similar to that described in Ch 2, 5 Site-specific support structure design evaluation, as applicable to the ‘other installation’ under consideration. The evaluation may include independent analysis, if required by the applicant.

6.3.2 If cables are required to be evaluated as part of this module, as an ‘other installation’, the assessment shall address the main design aspects of the cable system, including material qualifications, prototype testing, design methodologies, cable cross-section and global system configuration proposed. Cable core and optical components should be reviewed to confirm cables selected are capable of transmitting power and signals as required by the project specification. These components are often supplied with type certification, and review should confirm suitability of the certification range against the required project conditions, ambient temperature, current, voltage and frequency levels. Critical mechanical design considerations for the cable include strength, and fatigue capacity for the intended design life in the specific project application. The design of associated ancillaries and cable protection systems shall be considered against project conditions, with special consideration for sea bed interaction for the cable configuration chosen.

Although a number of recognised standards for design aspects relating to strength, protection, fatigue and ancillary items are widely applied to umbilicals and flexible pipes, many of the analysis methods presented can also be applied to the design of power cable systems. The established requirements from ISO 13628-2 Petroleum and natural gas industries — Design and operation of subsea production systems — Part 2: Unbonded flexible pipe systems for subsea and marine applications and 13628-5 Petroleum and natural gas industries — Design and operation of subsea production systems — Part 5: Subsea umbilicals can be applied to the general qualification approach for materials, design methodologies and prototype testing. Complementary testing specific to the electrical cables, such as that provided within CIGRE publications, can be applied within the framework of these recommendations.

The review will be supported, where required, by independent analysis assessing the tie in location and global configuration response to extreme and long-term fatigue loading.