Industrial PhD programme
by Ranjan Sharma
Study no. s051018
PhD thesis 
Period
September 2008 – January 2012
PhD defense
Date & Time: Wednesday 21st December 2011 at 13.00
Location: DTU, Building 101, Meeting Centre S02
Examiners: Professor Tore M. Undeland,
NTNU-Trondheim, Norway
Professor Torbjörn Thiringer,
Chalmers University of Technology, Sweden
Chief Engineer Jens Peter Kjærgaard,
Energinet.dk, Denmark
Chairman: Associated professor Esben Larsen
DTU Electrical Engineering
Supervisors
Associated professor
Tonny W. Rasmussen ELC, DTU Electrical Engineering
Professor
Michael A.E. Andersen ELE, DTU Electrical Engineering
Power System Engineer
Kim Høj Jensen Siemens Wind Power
Affiliated supervisor
Senior Engineer Energinet.dk
Vladislav Ahkmatov
Project introduction
Wind power plants are moving off-shore for reasons of good wind conditions and keeping them out of sight. Wind conditions off-shore are generally better than on-shore and hence the capacity factor of individual wind turbine or that of the entire wind farm will increase. Bigger the size of wind farm, larger the amount of wind turbines required. Considering the distance that has to be maintained between the wind turbines, the size of the wind power plant could well be several tens of sq. Km. The distance of the power plant from the coast will also increase accordingly. For relatively short distances between the wind farm and the connecting transmission grid, it is often considered best to use AC transmission where all the equipments and technologies are well known. The major problem with an AC transmission system is, however, related to HVAC cables and the surplus of reactive power that increases with the length of the cable. This also introduces more losses in the transmission system. Use of overhead transmission is not practical in off-shore conditions. Transmission system based on HVDC is intriguing under these circumstances. Voltage source converter based HVDC systems have advanced in recent years. They can be made to control the active and reactive power exchange with the grid independently.
In consideration to all these factors, this project in particular will be focused on different aspects of HVDC transmission system connecting an off-shore wind power plant. A brief summary of the project is listed below.
- Identification of determining conditions (especially distance and power level) under which DC transmission becomes more feasible. This part will also include the investigation of AC or DC technology for the collection network.
- Investigation of suitable control strategy for the proposed HVDC system in relation to different power system operations (mostly determined by grid code requirements) as well as perform laboratory and simulation experiments for verification.
The project is conducted in co-operation with Siemens Wind Power and the Technical University of Denmark.
Link
• ORBIT database
2011-12-09 ras