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Customer Success Story
Reference: Netzgesellschaft Düsseldorf

Planning a target distribution grid "Südstadt" 

Netzgesellschaft Düsseldorf mbH, Germany

The task

Netzgesellschaft Düsseldorf mbH (NGD) previously operated two distribution networks: the city network and a network to supply the southern part, both networks were exclusively connected through the networks of the superordinate network operators Westnetz GmbH (high voltage) and Amprion AG (extra high voltage).

The concept to be developed under this target network planning was a high-side connection of the South City to the city network and the separation from the network operator Westnetz GmbH. The previous location of the substations should be considered questionable and the optimum for the future supply object locations should be determined.

Following this, a target network and implementation planning for the 10 kV and 25 kV network of “Südstadt” should be carried out, wherein it the decommissioning of the 25 kV network level should be pursued.

Our solution

The target network planning was carried out in several phases: During the preparation phase initially planning criteria and constraints to the development of a future network concept were developed. Here our planners intervened on their many years of experience from a variety of already carried out network studies. In the initial planning stage, they drew first a plan of “Südstadt” network in the network calculation program NEPLAN. Based on the load distribution, the existing cables and lines in 10 kV and 25 kV network and the possible 110 kV lines the optimal locations for the two newly created sub-stations have been identified.

Based on this, the experts determined the 110 kV side connection of new substations and devised concepts for future power structure of the underlying network layers. They determined the future main lines as well as the locations and functions of the central switching stations. To conclude the initial planning phase, the experts initiated from the established plans from the budget prices for to be incurred in the individual voltage levels investments.

The detailed target network planning of the 10 kV distribution network was the beginning of the second planning phase. Synergies across voltage levels should be used and adjusted, historically grown network structures as well as network unbundling should be enabled. The planners took into account the present power structure by possible given example in the restructuring XLPE cables and cross-sectional weak ground cable questioned.

The development of the target network was carried out in close coordination with NGD. Here that target network had not to meet only the agreed technical planning criteria, the efficiency of the planning was also detected by a reliability and cost comparison with the actual network. For the target network, a record in the network calculation program NEPLAN was created, where all necessary measures for the implementation of the target network were stored in separate graphic layers. In a final presentation to the customer, Hitachi Energy's experts explained the future network concept and the results of the target network planning.

In the third planning phase, the preparation of the implementation plan was carried out. Since the implementation of the target network for operational reasons and due to the short time frame can not be done in one step, developed and documented the project team initially on all voltage levels cables to be laid in the main roads from the target network dataset. Subsequently, all measures have been identified and documented, that must be implemented for swirling the feed of the old substations on the new substation. From this a first rough schedule for implementation was designed.

Following the target network planning Hitachi Energy received additionally the order for consideration of the insulation coordination and to evaluate the grounding systems of the new substation.

The customer benefit

The Hitachi Energy network planners have defined in this project together with the customer the course for the future development of the 110 kV, 25 kV and 10 kV grids of NGD. With the target network development the overall voltage levels usable synergies and a significant improvement in efficiency as compared to a 1:1 replacement have been achieved. The measures to be implemented have been extensively documented in a geographical plan. In addition, general planning criteria have been established to be used in future planning of NGD.

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