Wind break

BAE Systems has developed technology to filter out interference to air traffic control radar caused by wind turbine blades.

The Advanced Digital Tracker (ADT), which was developed by BAE subsidiary Integrated System Technologies (IST), acts as a postprocessor fitted between the radar signal processor and the display screen. The system - a box no bigger than a PC - uses complex algorithms and ‘fuzzy logic’ to filter out the interference caused by the wind farms and present a clear display for the air traffic controller.

Wind farms create ‘blind spots’ on air traffic control radar systems, leaving controllers unable to differentiate between the turbine blades and aircraft. According to Ian Metcalf, head of business development at IST, the problem must be solved quickly to ensure that the UK has a chance of reaching its Kyoto Treaty target of generating 10 per cent of energy from renewable sources by 2010.

‘To hit the 2010 target, onshore wind farms are the only viable option for the government,’ Metcalf said. ‘But at the moment, just over half of all planning applications by energy companies for wind farms are rejected on safety grounds.’

The technology should also make life easier for air traffic controllers. As part of the device’s installation, large, more detailed plasma screens will be used. These will integrate the primary and secondary radar signals, which are currently displayed on two separate screens, and will replace the older, round, black and green radar screens that do not give details of an aircraft’s height.

As part of a demonstration programme an RAF Watchman radar has been taken to Clee Hills in Wales to monitor radar interference from wind farms in the area. Next month the ADT unit will be taken to the site and the data recorded. The IST team expects the unit to reduce interference considerably.

Metcalf said: ‘If all goes well, and we expect that it will, the ADT will validate our computer predictions and we’ll see a significant degradation in interference.’

The proof-of-concept demonstration is the first of three phases for the project, which is being partly funded by the DTI. The second phase involves developing the technology to the stage where the Civil Aviation Authority’s Safety Regulation Board will withdraw its objections to planning permission for wind farms. The final phase will see the algorithms re-coded to put them into an acceptable format for use by civil air traffic controllers, with the system hopefully being installed at UK airports by the end of next year.

Another possible solution to the problem of wind farm interference could be to make turbine blades from materials used for stealth bombers, an approach being investigated by Qinetiq.

Metcalf said he believed there was room for both solutions, but that the ADT would prove to be far more cost-effective. ’The ADT is the best technical solution to today’s wind farm problems. As the use of farms increases, and the turbines increase in size, the problem is only going to get bigger.’