ABB DRIVE TRAIN: Test and R&D centre in Helsinki
The Grid Code defines the working conditions for the operators of the grid administrators and the distributer or end user concerning the operation of, and the connection to, the grid, how the grid is functioning, and connections to other grids. They are the rules to which generating plants have to conform in order that their product, the electricity generated at the wind farm, may be sold to the distributer for transmission to the end user.
Grid codes are not universal and can change even within countries from one grid operator (TSO) to another, as well as between connected countries. They are changing because of national governmental policies and even within a single TSO in time to suit the changes in growth and performance requirements.
Matching the output from a wind farm to the grid for onward transmission is facilitated by using wind turbine converters installed in each of the wind turbine installations. These have to be selected to fit the wind turbine size and the compliance to the local grid code that is applied. It is the wind turbine converter that can connect a standard design wind turbine to the variable conditions of the grid, they are the interface with the country or region where the wind turbines are located. The use of a well matched converter will improve the wind turbines’ drive train efficiency and reduce direct costs. In recent years the increasing technology used in wind turbine converters has changed the fundamental characteristics of the wind turbine from being just a source of energy to become an active power source.
Although hardly yet on a mass production level on the scale of a car manufacturer, the fact remains that using a standard design for a wind turbine provides cost reduction possibilities for the manufacturer. It offers also a financial and operational advantage for wind farm operators by being able to use fewer variations of equipment and procedures, and making the work of their O&M technicians simpler especially with cross border utility companies experiencing different grid codes.
The wind turbine manufacturing company can use the converters to match the wind turbine with grid code in force at the wind farm location by adopting different configurations in both converter hardware and software. There is an obvious cost reduction advantage when using components for the wind turbine that have already been tested by avoiding having to make unnecessary changes to the design of the wind turbine.
The perfect match
Then the question to be answered is how do you find the best way to match the wind turbine to the grid with the applicable grid code for the location at which the wind turbine will be working? Offshore WIND was invited to Helsinki where ABB have their drive train testing laboratory to see their testing facility at first hand.
Their facility is working to the 2nd edition of the IEC 61400-21 standard which specifies the testing practices for wind turbines in real and accurately simulated full power conditions at multi megawatt levels. It is necessary that the testing procedures are carried out with full scale components, the transformer, voltage divider, generator and converter, enabling conceptual multimegawatt testing of doubly-fed and full converter wind turbines. This is a prime method to provide their customer with the resulting data which will accurately portray the dynamic operation of the wind turbine and the wind turbine converter.
The facility is not only useful for their clients, it also enables ABB to increase the development of their own drive train technology for their own converters and generators manufactured at this site in Helsinki and others around the world. This Helsinki R&D operation is responsible for a large proportion of ABB’s total R&D worldwide.
The ultimate aim to have European grid code harmonisation is being brought closer to realisation at the ABB laboratory in Helsinki. Although this harmonisation could inevitably reduce the necessity for wind turbine manufacturers or operators using the ABB laboratory testing facility, the drive train testing facility is also being used to test proposed grid codes and analyse data and provide feedback to the various parties, including the grid code harmonisation working group of the European Wind Energy Association, who are working towards this aim.
ABB use the local Helsinki grid as a power source and so great is their power demand during testing that without having the proper isolating gear installed at their facility they could bring the city of Helsinki close to a blackout!