Grid Code Compliance – Wind farm HVDC connection

University essay from Uppsala universitet/Elektricitetslära

Abstract:

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.

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