08/07/2023
Source: Energy & Management Powernews
The transmission system operator 50 Hertz is testing a new operating mode for the transformers in a substation. This allows them to be utilized to a higher degree, and redispatch costs fall.
Transformers in the transmission network are not fully utilized in normal operation: Reserves are always kept free to respond to incidents. In the so-called "curative system management" 50 Hertz is currently testing a new procedure at the Pasewalk substation (Mecklenburg-Western Pomerania).
The idea behind it: By exploiting the thermal inertia of the transformers, they can now be utilized at 75 percent instead of the previous 70 percent. As a result, more electricity from renewable energy sources can be fed from the distribution grid into the transmission grid and transported away to the southern German load centers, according to a statement from the transmission system operator. The necessary Redispatchbedarf decreases disproportionately.
In the rare case of a transformer failure, the utilization of the remaining transformers increases and can thus for a short time even be above their load limit. As a countermeasure, the feed-in from the distribution network is reduced so that the transformers are again below their load limit after a short time. Technically this procedure is unproblematic, since the limit value for the operating temperature of the transformer is not exceeded in the short period, so 50 Hertz.
A first evaluation of the pilot project shows according to data of the transmission system operator that by the new driving mode in the transformer station in Pasewalk in the first half-year 2023 substantially more river from the distribution net into the extra high voltage net was transported. It was possible to avoid down-regulating renewable energy in the amount of 2 million kWh. 50 Hertz puts the redispatch costs saved at 176,000 euros. Since 2023 has been a comparatively low-wind year so far, the transmission system operator expects even higher savings in redispatch costs in the future.
"The efficient integration of renewable energies into our power supply requires a set of different strategies for the secure operation of the power grid. This includes comprehensive grid expansion as well as innovative concepts in system management," emphasized Dirk Biermann, Managing Director Markets and System Operations at 50 Hertz. With the curative transformer driving method one successfully tested such a concept.
Due to the good experiences with the new procedure in the Pasewalk substation, it is now to be transferred to further plants. In particular, grid interconnection points to the distribution grids, in which particularly much renewable energy is fed in, come into question.
Author: Günter Drewnitzky
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