Improving the reliability of industrial multi-MW wind turbines

Abstract

Although wind turbine gearboxes are designed to remain in-service for 20-25 years, this is not normally the case due to defects initiating and developing prematurely. A large number of gearboxes fail after 7 to 8-years in service. In offshore wind farms gearbox failures have been reported after only 1-2 years in service leading to noteworthy production losses. Reliability issues associated with wind turbine gearboxes are yet to be resolved. Within this paper the quality of materials used for manufacturing wind turbine gearbox gears and bearings has been evaluated. The damage mechanisms affecting gearbox materials have been investigated based on metallographic analysis carried out on failed samples removed from in-service industrial wind turbines. Finite Element Analysis (FEA) has been carried out in order to simulate damage initiation and propagation under in-service conditions. The results have been compared with the experimental observations made on the failed field samples and have been found to be in good agreement. The applicability of acoustic emission in detecting and identifying defects in different wind turbine gearbox components remotely has been assessed following measurements in the field.

Benchmarking parameters for remote electrochemical corrosion detection and monitoring of offshore wind turbine structures

“…These alloys will have corrosion protection such as sacrificial anode and/or protective coatings because of their exposure to aggressive environments such as seawater or salt spray, ultraviolet radiation, microorganisms. Details on corrosion prevention methods and protection of WT components can be found in the previous studies …”

“…The WT materials for the nacelle gearbox and the rotor hub are mainly carbon steels with a small percentage of aluminium and copper alloys. Stainless steels and aluminium alloys that have low wear (scuffing) resistance are not suitable for gears; instead, case‐hardened or chromium‐molybdenum alloy steels (18‐5 or 17‐6 NiCrMo) are used . There is a larger percentage of copper alloys found in the generator because of its good electromagnetic conductivity.…”

“…This leads to the requirement of a technology development for a cost‐effective end‐to‐end nondestructive testing (NDT) corrosion detection and monitoring solution for the offshore WTs . This solution should look for methods that allow for a continuous monitoring of a system or a system condition by an operator from a remote and safe control room by means of detecting or monitoring physical or electrochemical changes, for example, the thickness of the oxide films and discontinuity on the surface of the materials.…”

Utilisation of Ensemble Empirical Mode Decomposition in Conjunction with Cyclostationary Technique for Wind Turbine Gearbox Fault Detection

“…Gearbox faults and failures take considerable time to repair. Hence, they result in major downtime and loss of production capacity leading to increased maintenance costs for wind farm operators [3][4][5][6].…”

Evaluation of damage mechanics of industrial wind turbine gearboxes

“…Although wind turbines are designed to last at least 20 years, the wind energy industry has suffered from premature gearbox failures from its inception. Given that gearboxes are amongst the most expensive sub-systems of utility-scale wind turbines, their premature failure increases the cost of wind energy production considerably [1][2][3][4][5][6][7][8] . Direct-driven design configurations also exist and have been developed to remove the need for a gearbox.…”