Design and Analysis of Electric Powertrains for Offshore Drilling Applications
Introduction
Industrial-PhD - doctoral studies funding scheme of the Research Council of Norway. Real-world challenges are addressed by an industrial partner - MHWirth, whereas research relevant methods are provided by an academic institution - University of Agder. Therefore, my research activities were distributed between the company and the degree-conferring institution.




Motivation
  1. Hydraulic drives have been a primary solution in the offshore industry since 1970s.
  2. Risk of leakage, noise and other disadvantages make this type of actuation system not suitable for environmentally sensitive regions.
  3. Recent advances in power electronics made Alternating Current (AC) drives more accessible.
  4. Their main benefits are:
    • No risk of electric spark generation
    • High reliability
    • High robustness
    • Easy maintenance
    • Long life and low cost.
Project Focus



Comparative analysis between hydraulic and electric actuation systems used in offshore applications in terms of:
  • Productivity
  • Reliability
  • Environmental impact
  • Cost effectiveness.





Research Methodology


As a case study, the Vertical Pipe Racking System of MHWirth (MH VPR) was selected.
  • Modeling and simulation in a virtual environment.
  • Numerical optimization to design degrees of freedom (DOFs).
  • Focus on controller, motor, and gearbox.
  • Validation of selected solutions.
Main Contributions
  1. Design optimization of electric powertrains:
    • Globally optimal solution
    • Modularity and options for development.
  2. Temperature rise evaluation of AC motor drives:
    • Arbitrary load conditions
    • Better design flexibility.
  3. Systematic selection of motion profiles:
    • Minimization of fatigue and vibration severity
    • Extension of lifecycle.
  4. Sensorless control of induction motors:
    • Reduction of the number of sensors
    • Enhanced motion control of offshore drilling machines.
  5. Installation of laboratory equipment:
    • Performing scaled-down experiments
    • Emulating operation of full-scale equipment.
Reference
Witold Pawlus
Design and Analysis of Electric Powertrains for Offshore Drilling Applications
Ph.D. Thesis, University of Agder, 2016, ISBN: 978-82-7117-839-0.