Liu, Wenzhao

PROJECT TITLE: Power Electronics and Power Quality in Maritime Microgrids Systems 

PhD period: 2015.11.15 – 2018.11.14.
Section: Power Electronic Systems
Research Programme: Microgrids
Supervisor: Josep M. Guerrero
Co-Supervisor: Mehdi Savaghebi 
Contact Information

Collaborators: Yanshan University, China and Gdynia Maritime University, Poland.
Funding: Scholarship from China Scholarship Council and the Department of Energy Technology, AAU. 


Vessels working out harbor areas and further from coastlines faced electronic pressure without land-based communities. This challenge may be changed by maritime microgrids systems. As a class of isolated power system, typical electrical power systems in ships are composed of some main components like generators, pulsed loads, motor drives, energy storage and management, voltage and frequency regulators, DC/AC systems and so on as shown in the following figure. However, one of the key technical issues may be focused on electrical quality and continuity of power supplies in the systems. Vessels crews may suffer from various power quality problems such as voltage dips, blackouts, abnormal changes in voltage and frequency, and even in harmonics situation. The converters installed onboard play an important role and should be controlled to ride through these faults to ensure the reliable and flexible operation of several complex devices and loads onboard. Moreover, the Point of Common Coupling (PCC) voltage and frequency quality should be enhanced simultaneously as well as the current harmonics suppressed in the microgrids systems.

For this project, the power quality will be investigated by using new models and tools in connection with topology of power converters installed onboard to meet some specific requirements for vessels. Various methods to real signals based on transforms like CZT, DFT and wavelet may be used to analyze power quality phenomena. Digital filters like IIR and FIR can be applied to achieve the desired response characteristics to test related measuring equipment for the systems modeling in the research. Moreover, In order to enhance the power quality, the research will be focused on the other following aspects:

  • Signal Processing techniques for analyzing power quality phenomena
  • Flexible and Coordinated Control Strategy.
  • Continuity of Power Supplies Onboard
  • Power flow analysis in ships
  • Power Compensation and Harmonic Suppression


Publications in journals and conference papers may be found at VBN