The application of EU2016/631 RfG or VDE4105-4120 for Howden KK&K Steam Turbines

Monday, 25 July 2022




The energy transition is shifting power generation from a few large power plants to numerous small and decentralized systems.

In Europe, to ensure that electricity grid stability is maintained, EU2016/631 regulations have been developed for implementation throughout the European Union.  Now that these regulations have  been incorporated into European national standards VDE4105 – VDE4120, there are three ways to ensure networks conform to these regulations:

  • A unit certificate for machines,
  • A prototype process that also leads to a unit certificate,
  • Individual verification procedure for each machine.

Typically, the certification is performed by a third party.

With these certification procedures, manufacturers, plant operators and grid operators are now faced with additional responsibilities and workload. This is especially the case with customer-optimized, smaller steam turbines where the certification process can also be a commercial challenge.

The Howden KK&K steam turbines are often used to convert residual steam into electricity, as a reducing station in the likes of heating networks or biomass plants. In order to generate maximum power out of the customer process parameters such as steam volume and steam pressure, each machine is designed and optimized according to that customer’s specific requirements.

For these types of turbines, the only reasonable way of certification is through Option 3, the individual verification procedure. The additional costs caused by this, which do not add value, can amount to up to a third of the total machine costs, representing a significant economic burden.

Why is individual verification so costly? There are two major challenges for this approach, namely the technical requirements of all the components and the procedural coordination of many participants in the process. The technical requirements are usually met by two or more components, which often come from different manufacturers and consideration of the interaction of these components is essential, especially in the evaluation of dynamic processes.

In the procedural coordination there is a requirement to show how all those involved - from network operators, plant users, manufacturers, numerous suppliers, test laboratories to accredited certifiers – work together in order to bring the process to a successful conclusion.

By mastering this complex process, system certification is possible for individual customer-optimized steam turbines.

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