Independent thesis Advanced level (professional degree), 20 credits / 30 HE credits
A rapid development of offshore wind power is planned in GB as a part to fulfil the
EU2020 targets. 25 GW wind power capacity has been awarded to developers in nine
different offshore zones outside the coast of UK. VSC-HVDC transmission is
expected to be a both technical and economical favourable solution for transmitting
the power into the main grid. This study investigates if such a transmission solution
could comply with the regulatory framework in UK.
Vattenfall and Scottish Energy Renewable will be part of this development and have
been awarded the rights to develop 7200 MW of wind capacity outside the cost of
East Anglia as a part of the offshore expansion plans in UK. The zone is broken down
to several projects. The first project is called East Anglia ONE and this project is used
as a reference case in this study.
The GB Grid Code has been broken down into four areas, voltage and frequency
variations; fault ride through requirements, active power control and reactive power
control. Load flow calculations and dynamic simulations are designed to investigate
compliance of each area. Further, simulations to investigate the interaction between
the wind turbines and the offshore converter stations where done.
A model representing East Anglia ONE was built in PSS/E and used to investigate grid
codes compliance by load flow calculations and dynamic simulations. Data from earlier
studies at Vattenfall was used to get a good representation of the wind park. A model
representing a HVDC-transmission solution was provided by ABB.
The results from load flow calculations and simulations show that a HVDC-solution
can comply with the investigated parts of the grid codes. The limiting factor seems to
be the capability to inject enough reactive power to the gird at small voltage dips
during normal operation. This capability can, however, be enhanced with the right
tap-changer settings at the onshore converter transformer.