X-Multirotor DfM

In the X-Energy sub-project Multirotor DfM (Design for Maintenance), the research focus is on the maintenance-friendly design of a multirotor wind turbine for offshore use.

Multirotor DfM builds on the findings of the X-Energy sub-project X-Multirotor.

The aim is to be able to better estimate operating costs and develop further technical solutions to minimize operating costs.  Multirotor DfM is divided into three areas: analysis, design and optimization:

Analysis

• In the analysis, tools are developed or existing tools are expanded so that an assessment of the ease of maintenance is possible. Technical system availability and maintenance costs are used as relevant key figures. These are then integrated into the calculation of the levelized costs of electricity (LCoE) as a superordinate and decisive key figure.

Design

• Design concepts and service strategies for the optimal operation of multirotors are developed in the design phase.

Optimization

• With the help of the previously developed tools, design concepts and service strategies, the multirotor concept with the lowest levelized costs of electricity (LCoE) is calculated in the final optimization.

Results

A key result of the project is the quantitative analysis of the operating phase of multirotor wind turbines under realistic technical, logistical, and weather-dependent boundary conditions. For this purpose, a simulation model (PyWinda) was developed in the project, which allows for a systematic investigation of failure events, repair processes, maintenance strategies, and their cost effects. PyWinda served as the methodological basis for the comparative evaluation of different plant and operating concepts. The simulations conducted show that larger multirotor configurations tend to have higher technical availability and lower specific operating and maintenance costs than smaller multirotor or single-rotor configurations with the same total output of a wind farm. These effects result in particular from the bundling of maintenance and repair measures within a multirotor system, reduced travel and transfer times for service vessels, and the possibility of deploying several service teams in parallel on a multirotor system. Another key finding is the strong influence of the selected maintenance and response strategies on availability and yield losses. In addition, the design-for-maintenance concepts developed and evaluated in the project show that integrated maintenance systems such as on-board cranes, elevators, and modular rotor nacelle assemblies have the potential to significantly reduce downtime and logistical dependencies.