Lightning Can Strike Twice
Turbine blade lightning damage accounts for more than 75% of the breakdown costs associated with Gamesa G8X, G9X, and G114 turbines. For example, G90 lightning-related costs can quickly add up to US$70,000 for self-operating wind operators (Figure 1).
Ensuring a continuous low impedance path to the ground is of paramount importance in Wind Industry best practices [1].
Are you taking advantage of the latest technology to reduce the risk to your blades?
Figure 1: Blade ownership costs for G90 (Costs in USD).
Costly and Unnecessary Risks
Lightning strikes cause major system damage to the blade and tower structures, as well as to costly electronic components. The risk of blade damage is particularly high because of lightning rebounding within the blade without adequate grounding.
Initiating a manual reset to restore the asset after a lightning strike also creates a significant health and safety liability, not to mention the costs associated with lost asset production and availability. Safety risks and production losses are exacerbated in the presence of lightning storms, as any lightning within a 30-mile radius of the asset means that maintenance personnel are unable to access the turbines even for a simple reset. Turbines should be most profitable during peak winds, but if they require a local reset due to grounding issues, it could be hours before they recover, and by then ideal conditions have passed.
Avoiding Costly Consequences
The costly consequences of lightning strikes can be reduced by eliminating the air gaps between the nacelle and the blades (Figure 2). These air gaps put enormous strain on the blades as lightning cannot easily discharge and the energy bounces back up the blades.
The turbine Main Bearings can also be critically damaged as a result of a lightning strike that is not properly grounded. Bearings are difficult to monitor and require tedious and costly inspection after lightning strikes.
a)
b)
Figure 2: (a) Air gaps between the blades and the nacelle in Gamesa 2MW Turbines. (b) SLPS bridges the air gaps and provides a continuous, low impedance path to the ground tested to withstand a 200kA lightning strike.
Designing the Optimal Lightning Protection System
To comply with International Wind Turbine Standard IEC 61400-24, all subcomponents of a wind turbine should be protected according to Lightning Protection Level 1 (LPL1), the highest standard.
AP Renewables’ Static + Lightning Protection System (SLPS) features a patented continuous contact brush design with a 1 ohm impedance compared with the high impedance of the 2” air gap in the OEM lightning protection system.
Unlike other lightning protection products on the market, such as discrete brush products, the SLPS features a unique burst and earth lead system that maintains continuous low impedance. The SLPS ensures that the current produced by a lightning strike is able to travel safely from the blade to the nacelle bedplate without exposing the Main Bearings and Blade Bearings to electrical discharges.
Independent tests have shown that the SLPS facilitates faster and more controlled discharge of the lightning current compared with the control turbine without the SLPS installed (Figure 3). This results in faster dissipation of the destructive energy of the lightning in the turbine equipped with the SLPS (Figure 4). IEC 61400-24 Lightning standard uses a lightning wave that is 35 times faster in rise time (known as 10/350µS) to simulate the effect of lightning. SLPS has been tested for full compliance with this waveform.
Figure 3: Lightning discharge control for Gamesa turbines with (green) and without (red) the SLPS installed
Figure 4: High voltage current discharge for Gamesa turbines with (green) and without (red) the SLPS installed.
Upgrade Your Gamesa Turbine to Meet Industry Standards
SLPS upgrades Gamesa to provide continuous grounding that bring lightning protection system up the standards of the competition and level the playing field.
The SLPS is an affordable, easy to install lightning protection system rated for LPL1. The SLPS allows complete redirection of the current from the Blade Bearings and Main Bearing, as is the industry accepted best practice.
The SLPS has been independently tested to IEC 61400-24 level 1 at 200kA and 10 MJ/Ω energy exposure by world recognized lightening experts in wind, the PolyTech Laboratories of Denmark (former GLPS) and NTS Laboratories in the U.S. The SLPS can be easily and quickly installed on your existing Gamesa turbines.
To find out more about how the SLPS can increase the availability and profitability of your fleet, contact AP Renewables.