The Nordex Group has carried out extensive tests on the rotor blade of the latest wind turbine in its Delta4000 series to ensure it meets industry standards – and is able to weather an electrical storm.
The international standard IEC 61400 specifies technical requirements for the design of wind turbines and an independent certification body must confirm compliance with these standards.
This includes the comprehensive structural testing of rotor blades and is one of the prerequisites for the approval and operation of new turbine types.
Over the past 11 months, Nordex has put the N175/6.X blade through mechanical tests on the accredited rotor blade test rig at the Fraunhoger Institute for Wind Energy Systems IWES in Bremerhaven.
The measurements of the properties of the N175/6.X rotor blade, such as natural frequencies and damping parameters, as well as the electrical resistance values of the lightning protection system, aimed to validate the simulations in practice.
The measurements were carried out on one of the first rotor blades, which was manufactured at the Nordex Research and Development Centre in Rostock.
Nordex said the mechanical tests, in which the rotor blade was subjected to static load cases and fatigue tests, corresponded to the previously simulated service life.
During the entire test period, Nordex said the rotor blade performed as expected.
Critical parameters such as deflections, strains and natural frequencies were consistently within the permissible tolerances, the company said.
In addition, a 15-metre-long rotor blade tip of the N175/6.X with integrated anti-icing system was subjected to extensive lightning tests.
High-voltage impact tests and high-current tests were completed in Polytech’s accredited lightning laboratory in Denmark.
“It is crucial to test for lightning as close to real-life conditions as possible,” said Polytech’s test centre manager Andreas Christensen.
“We are pleased to service Nordex Group and a long list of customers from in and outside the wind industry with our accredited facilities, so we can make well-documented test results for certification or keeping momentum in their R&D projects.”
Head of blade materials, design and testing at the Nordex Group Hendrik Klein said: “At Nordex, we know the value of industry standards.
“These standards define the requirements for the design of wind turbines and also their compliance.
“This is becoming increasingly important as rotor blades today become longer and longer and rotate at higher altitudes.
“With the right material and design of the rotor blades, not only can the power of the wind be used optimally, but also the planned service life can be achieved, or the risk of lightning damage can be minimised.
“At Nordex, we also test more than is required by the IEC standard. Our goal is to achieve even higher product maturity.
“The results of the tests are therefore of great value to us as a manufacturer.”