External lightning protection system for wind turbine blades — preliminary aerodynamic results

Abstract

In general, there are three components making up a lightning protection system for wind turbines. These are the receptors, the down conductor and the grounding grid. Receptors and down conductors are usually found in the more recent wind turbine blades and where the down conductors are normally installed on the internal side of the blade. Consequently, the blades are vulnerable to damage and burn resulting from lightning strikes. The authors believe that a system with an external down conductor is likely to reduce the risk of damage when compared to the system having an internal down conductor. One could envisage an external down conductor would look similar to the one installed on a building or an aircraft. However, external down conductors may compromise the aerodynamic performance of the turbine blades. This paper reports the effect of external down conductors on the pressure coefficient distribution around the turbine blade. The blade profile (aerofoil) used is according to NACA 4418. Numerical simulations, using computational fluid dynamics (CFD), were conducted on an aerofoil without and with external down conductors of Imm thickness. The k-r turbulence model that is incorporated in COMSOL Multiphysics (CFD Module) was used for the simulation and the wind speed and angle of attack used was 5 mls and 50 respectively. The preliminary results show that the degradation on aerodynamic properties may not be too significant and these indicate that external down conductor arrangement could be considered.

A Drone-Driven X-Ray Image-Based Diagnosis of Wind Turbine Blades for Reliable Operation of Wind Turbine

“…For example, down conductor cables can be lacerated due to aged deterioration. The enormous energy of lightning current also can enable down conductor cable to be separated [37]- [39]. The damaged down conductor cable is likely to cause a problem (e.g., blades can be damaged), particularly if the lightning strikes again.…”

Experimental Study on Lightning Attachment Manner to Wind Turbine Blades With Lightning Protection System

“…External down improves the performance of the blade LPS [20][21] and works not only as a path of lightning current, but also as a receptor along the whole blade, which can be treated as a super diverter. In addition, external down conductor has quite insignificant influence on the aerodynamic performance [21]. However, it remains a question that whether it will affect the aerodynamic performance of the blade after being hit by the lightning strike.…”

Electrical and thermal performance of different core materials applied in wind turbine blades under lightning strikes

“…3,[13][14][15] The performance of the different blade materials under lightning strikes, such as breakdown voltage (electrical performance), burned, and cracking area (thermal stability), plays a significant role in lightning protection and there is an urgent demand that the prevailing core materials, such as PVC, PET, and balsa wood, be extensively tested to affirm their capability against lightning strikes. So far, most of the prevailing research focuses on the attachment characteristics of the receptor and down-conductor system by experiments, [16][17][18][19][20][21] plus large current experiments to study the structural damage of the wind turbine blades. [22][23][24][25] However, little research has been done regarding damage mechanism of the blade core materials under lightning strikes, for example, how does breakdown areas distribute, what are the damage characteristics of different core materials and how do the air products and water vapor expansion damage the core materials.…”