European Grid Code Development - The Road Towards Structural Harmonization

For historical reasons today's grid codes are diverse in structure and make use of many different terminologies and concepts. A trend is observed that grid codes become much more complex and constitute an ever increasing number of technical requirements There is an urgent need to start performing a grid code harmonization process for wind power plants, in order to turn this trend into a better manageable situation, looking at the worldwide perspectives for variable renewable generation in the near and long term.For this reason EWEA initiated in 2007 a working group to work on grid code harmonization, which has lead to the concept of structural harmonization. A detailed grid code template has been defined (see www.EWEA.org) to enable the formulation of a 'common language'. The template can be considered as a first part of a two-step process consisting of a structural harmonization to be followed by a (more slowly developing) technical harmonization.The Germany Grid code situation is a good example regarding the puzzling situation of standards in Europe. On the basis of this situation the need of a contemporary harmonization of European grid codes is shown.Fault ride through was introduced more than 10 years ago which should give reason to think that this issue is routine by now. However as shown by examples in the paper there are many larger and smaller conceptually issues which can not be considered routine. The most important aspects are how FRT voltage profiles are established and applied in practice.The last chapter of the paper is discussing detailed aspects of fault ride through (FRT) requirements that have been developed over the last four years in Germany. Some examples are given to demonstrate how unclear definitions could complicate a proper understanding of connection requirements.