Efficient fire safety for wind turbines

By Hilmar Maas, Fire Safety Solutions Expert, Building Technologies Division, Siemens

A fire in a wind turbine can quickly turn dangerous for people and the environment,

particularly if the nacelle or rotors catch fire, as these are hard to reach for emergency personnel. From a business perspective, the potential consequential damages are considerable. To address these issues, Siemens has developed an automatic fire detection and extinguishing system for offshore wind turbines. The first of these systems was installed at the Riffgat Wind Farm in the North Sea.

Because of their design, wind turbines, especially offshore units, are difficult to

access in case of an incident. The generators and engineering systems are typically

located in the nacelle – a hundred meters or more above sea level. 

Fires in wind turbines have been rare. However, the technical failure of individual

mechanical or electrical components could lead to a fire, which would present major

problems for emergency personnel. Because wind turbines are difficult to access –

onshore as well as offshore – it is hard to prevent a fire from burning through the

entire turbine, particularly a fire in the nacelle. This means total loss of the wind 

turbine, with serious consequences. Repairs are very expensive if the entire generator system, nacelle or rotors have to be replaced. 

Dangerous and expensive

An incident of this sort could quickly become expensive. Not only is the material to

be replaced pricey but the hoisting equipment and manpower needed for repairs are

costly as well. Additionally, the downtime of the damaged turbine affects the bottom

line.

In onshore wind farms, there is the risk that the fire could spread. In the summer, a

burning nacelle located on a ridge near a forest could pose a high risk for people

and the environment. In addition, the turbine is hard to access in these

circumstances. 

Fully automated offshore fire extinguishing system

To solve these issues, Siemens has been working on dedicated fire detection and

extinguishing systems for wind turbines. For offshore installations, the Siemens

Building Technologies Division has created the Active Fire Fighting System (AFFS).

This system detects fires in wind turbines and extinguishes them automatically –

without delay and without time-consuming fire fighting maneuvers at sea. The first

AFFS units are currently being installed in Riffgat.

AFFS combines intelligent Sinteso fire detectors with integrated ASA technology

(Advanced Signal Analysis) with a Sinorix extinguishing system, which uses nitrogen,

an inert gas, to fight fires. The fire detection system monitors the pain points and

system-relevant components of the wind turbines. If the AFFS detects a fire in the

nacelle or in the tower – for instance, caused by a short circuit in a control cabinet – 

the detector system transmits this information directly to the wind turbine's control

unit. If an additional fire detection element verifies the fire, the fire detection system

immediately activates the gas extinguishing system to put out the fire, leaving

behind no residue. The turbine is shut down automatically by its controller or, if

necessary, by operators at a control station, and the system is shut down under no-load

conditions. If necessary, the operators at the control station can take further steps, possibly

assisted by external technicians who can connect directly to the fire control panel via a VPN

Internet connection. Subsequently, the cause of the problem can be identified and the wind

turbine returned to operation in the shortest time possible.

Easy maintenance after a fire

By implementing an automatic extinguishing system, wind farm operators save

themselves the cost of a fire-fighting helicopter. Serious damage that could result

from the spread of fire can also be avoided. Using a remote connection from the fire

detection system to the Siemens Customer Support Center makes it possible to

trace alarms and configure the fire safety and extinguishing equipment from afar.

This saves additional costs.

The AFFS systems have a modular design, which is very beneficial in case of fire.

The elements can be replaced in the wind turbine by crane quickly and easily after a

fire, as well as for service. Even less experienced employees will be able to 

smoothly replace the fire detection and extinguishing system, as well as connect the

systems to the existing power lines. This makes it unnecessary to provide

maintenance for the modules once installed. Instead, the modules can be simply

replaced at the regular service intervals. The extinguishing modules, for instance,

are tested by their manufacturer for reliability and filled, if required. Only the nozzle

piping and fire detection lines are permanently installed. They are inspected visually

for external damage.