UL 4143:2018 Wind Turbine Generator- Life Time Extension (LTE).
1.1 These requirements cover the rules and procedures for the life time extension of wind turbines (LTE).
1.2 These requirements cover the process to obtain risk by relating the severity to their confidence level on accuracy for the failure mode.
1.3 Commercial aspects of wind farm operation are not covered by this Outline of Investigation.
1.4 These requirements are applicable to the on-shore wind turbines.
2 Glossary
2.1 For the purpose of this document, the following terms and definitions apply. Further definitions can also be found in IEC 61400 series.
2.2 CELL — Grouping of wind turbines. A cell defines a group of wind turbines within a wind farm.
2.3 DEL— Damage equivalent load
2.4 DLC — Design load case
2.5 FL — Fatigue load on component
2.6 LDD — Load duration distribution
2.7 LTE — Life time extension, a technical assessment that supports the continued use of a wind asset beyond a previously determined time-based limitation.
2.8 MCP — Measure-correlate-predict
2.9 MLC — Measurement load case
2.10 OEM — Original equipment manufacturer
2.11 RPN — Risk priority number, the RPN level of uncertainty in failure mode.
NOTE: This RPN calculation differs from the method mentioned in Analysis techniques for system reliability — Procedure for failure mode and effects analysis (FMEA), IEC 60812
2.12 RUL — Remaining useful life, the time frame of a safe operation of wind turbine(s) or a wind farm.
2.13 SCADA — Supervisory control and data acquisition.
6 Requirements for life time extension
6.1 General
6.1.1 In order to extend the lifetime of a wind turbine based on RPN determination criteria, the wind turbine(s) in a wind farm shall comply with the requirements mentioned in Sections 6.2 — 6.7.
6.2 Step 1: Requirements for external conditions
6.2.1 Operational historical data of external conditions relevant to the structural loading of the wind turbine(s) in the wind farm shall be used.
6.2.2 To assist in determining site external conditions SCADA data, met mast data, and/or public databases may be used. The respective source shall be named.
6.2.3 To cover the seasonal variations in wind characteristics, the measurement period shall cover at least 12 months. The measurement device set-up except for the met mast location shall comply with Wind turbines — Part 12-1: Power performance measurements of electricity producing wind turbines, IEC
61400-12-1. The on-site measurement location shall be chosen to achieve representative measurements for the wind turbine(s) under assessment.
6.2.4 The analysis of the measured data shall comply with Wind turbines — Part 12-1: Power performance measurements of electricity producing wind turbines, IEC 61400-12-1 or other equivalent standard like MEASNET, as applicable.UL 4143 pdf download.