Challenges in a distribution network

The success of the energy transition means that renewable energies have to be integrated on a huge scale. We are already seeing massive problems on days when large amounts of decentralized energy is being fed into the distribution grid and this is only set to worsen as the planned expansion of photovoltaics and wind energy comes on line. The most common problem is voltage range infringements. In accordance with the DIN EN 50160standard, a voltage range of ±10 % around the standard voltage should be observed in the low-voltage grid. Since below the medium-voltage level there is currently no further regulation equipment at grid operating level, the entire tolerance range of 20 % has to be split over both the medium- and low-voltage grids. In accordance with the current FNN guideline, 3 % of this is available in the low-voltage grid and 2 % in the medium-voltage grid for energy generated in decentralized locations. The remaining 15 % is used for voltage drops during supplies and for the tolerances of regulation equipment and actuators usually determined by the system technology.

A 2 % or 3 % increase (the maximum permitted) in voltage resulting from feed-in is currently reached with relatively low levels of feed-in power from renewable energy sources. This explains why the grid's limit on its ability to absorb more power is very often much lower than the ampacity of the equipment (especially cables) used. As a result, the problem described would lead to huge limitations on further expansion of renewable energies being generated in decentralized locations. However, because the operators of distribution grids are required by law on the one hand to immediately connect decentralized generation systems to their grid and on the other hand to continue to ensure a reliable supply voltage within the permissible tolerance limits, they are continually being forced into capital-intensive grid expansion work such as laying additional lines or installing more local grid stations even though their equipment is nowhere near its ampacity limit.

ECOTAP® VPD® is an on-load tap-changer for voltage regulation distribution transformers from Maschinenfabrik Reinhausen that offers an economical alternative to network expansion.