DescriptionTesting of lightning protection measures on wind turbine components provides fundamental improvements to wind turbine reliability. Full-scale testing of blades and nacelles is regarded as the most exhaustive mean to evaluate lightning performance, identify weak-points, and improve the lightning protection design. The continuous increase of dimensions of the test objects also increases the effective stray inductance, leading to a practical challenge of injecting the full lightning current into the test object, as is defined in in IEC 61400-24 Ed.1.0 Wind turbines – Part 24: Lightning protection. This circumstance led to the formation of the project “Enhanced Lightning effect Testing (ELITE)” under which was designed, constructed and prototype tested a novel extendable high-current crowbar impulse generator.
In this work, the concept of the generator is introduced, the components are described and performance is evaluated for single modules. The extendibility of the generator is achieved by modularity of 12 individual high-current impulse generators cuboids, each equipped with an intrinsic capacitor bank, spark-gap, and a crowbar consisting of 45 series-connected rectifier diodes. Each module has a charging voltage of up to ±100 kV and a discharge current of 125 kA and can be used as an independent unit. By series and parallel connections of the modules, the capabilities of the resulting generator can be modified and tuned to the specific test item. During testing, the modules are arranged around the device under test which effectively minimizes the stray inductance of the circuit.
The audience will be introduced to the principles of high current full scale testing according to IEC 61400-24 and special focus will be placed on the limitations due to the increased size of full-scale test objects. Furthermore, test results from a prototype high current impulse are used to verify the principles of lightning current injection to test samples.
|29 Jun 2017
|European Academy of Wind Energy, Germany
|Degree of Recognition