Call for tenders' details

Supply, installation and maintenance of 2 battery storage systems - 2 lots.
Contracting authority:
European Commission, Joint Research Centre (JRC)
TED publication date:
Time limit for receipt of tenders:
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Question details
Points A4 and C6 - Technical Specifications: "smooth" transition from the on-grid to off-grid
On page 4 of the technical specifications, it indicates that the system should permit a "smooth" and automatic transition from the on-grid to off-grid state and vice versa (point A4) and it requires a switch to do so. At the same time, it indicates (point C6, page 5) that the system (being an active system) must be able to follow the requirements concerning the operation LVRT, which is in conflict with the requirement A4 unless the smooth transition, for which we are talking about, has certain time frame. We are asking 1) [how] to be able to have the features of this smooth transition on-grid <-> off-grid (time frame for opening the switch in case of voltage absence) and how to relate this with the LVRT characteristics (parameter of enabling the operation LVRT?)
The system can be operated in 3 different modes (see requirements A4, A5, A6, B1, B9, C1, C5, C10 and the explanatory notes on page 7): 1) Grid connected. In this case, the battery system is meant first to support the grid. LVRT functions should be available and the system will disconnect only at the last moment. 2) Island mode (see page 7, under the title: "Explanatory and requirements details" ) 3) Microgrid (UPS like). In this case, the system is meant first to protect sensitive loads. Priority is given to smooth transitions (for the protected loads) from island to grid-tie.