Modeling as Support for the Implementation of the Project "Renewal of the Töging Power Plant"

The energy provider VERBUND Innkraftwerke GmbH is planning the construction of the new weir Jettenbach and the powerhouse Töging on the river Inn in Germany as part of the project "Renewal of the Töging power plant". The new construction is necessary due to the old-age of the plants (commissioning 1924) and the associated technical needs for renewal. The new weir Jettenbach is to be built about 50 m downstream the existing weir and the new construction of the Töging hydroelectric power plant is located on the orographic right side of the existing powerhouse. Until the completion of the new buildings, the existing weir and power plant will remain in operation. This is a special challenge for the planners and contractors as well as for the operator during the construction phase.

The renewal of the existing diversion hydropower plant Töging and its weir Jettenbach requires testing of several construction components. Therefore, physical and numerical modelling were performed. The construction phase for the weir was tested and significant parameters like flow velocities or shear stresses were determined. Parallel operation of both weirs, the old and the new one, are critical and had to be studied. The optimization of the stilling basins, flow pattern to the existing (residual water) hydropower plant, the scouring of the riverbed and new developed downstream fish passage structures were tested and optimized.

As mentioned already, the existing hydropower station Töging should be in operation during most of the construction time. Thus, numerical and physical tests were carried out both in the upstream part and in the downstream reach to fulfil this requirement. To guarantee a most sustainable operation of the new power station for decades, approach flow to the turbines had to be optimized extensively. The application of numerical tools and physical models led to a successful implementation of the planning phase.

The above-mentioned fish ladder, which is needed today at many hydropower plants in Europe, is not yet state of the art and satisfactory solutions are sought in a variety of ways. In this project a solution was found in a scaled physical model test by measuring and determining flow fields which suggest that the system works.

This contribution exemplifies some results of the investigations.