Situation
The municipal utilities Stadtwerke Fröndenberg operate extensive 30-kV, 10-kV, and 400-V systems with two 110/30-kV transformer substations and three hydro power plants on the Ruhr. Decentralized producers including wind farms, cogeneration plants, and photovoltaic plants also feed power into the system. To maintain the voltage and supply quality and ensure simple system operation in the light of revised legal constraints, the distribution network had to be optimized both technically and economically.

Problem
The 30-kV, 10-kV, and 400-V distribution networks have grown organically, the number of applications for a 400-V connection of photovoltaic plants to the system is growing, closure and opening of commercial businesses alter the load centers, converter-fed machines and modern process technology make increasing demands on the local supply connection. Simpler network operation was required as well as ongoing technical and economical expansion.

Solution
We created a wide area network model of the entire area of coverage with all its voltage levels – from the service connection to the 110-kV network. Based on our system analysis and a strategic plan for the MV and LV networks, we developed simplified powerful system structures. They were tested for feasibility and then implemented in stages making use of synergies.

Service
Today, we update our simulated system model of the municipal utilities every year, thus providing a constant overview of all MV and LV system levels. This allows the system operator to assess the situation quickly when considering system expansion and the local power system quality, for example, before connecting additional loads or decentralized electricity producers.

We advise the Fröndenberg municipal utilities directly on any problems that arise. They can access the technical competence, experience, and problem-oriented calculations of the overall system model whenever it is needed.

Stadtwerke Fröndenberg (in German only)

Overview