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Case Study

Reference: Energy Thun

Planning a 16 kV target distribution grid 

Energy Thun AG, Switzerland

The task

Energy Thun AG operates a 16 kV distribution grid to supply residential, commercial and industrial customers in Thun with power. On behalf of Energy Thun AG, Hitachi Energy initially assessed the distribution grid by doing an actual state analysis of the grid to identify any structural weak points. Another aim was to adjust historically developed grid structures and to disentangle the grid. Within the framework of target grid planning 16 kV grid variations which ensure high efficiency regarding grid costs and the provided supply quality were to be developed, analyzed and assessed.

Our solution

At the beginning of the project grid data was gathered and the grid was simulated in the network calculation program NEPLAN. First of all Hitachi Energy's experts checked an already existing NEPLAN data set for plausibility and added missing data or corrected some of the existing data.

During the subsequent actual state analysis for the grid the consultants performed load flow, short circuit current and voltage quality calculations. Through calculations they also determined the reliability parameters, the frequency of interruptions and the non-availability.

To complete the analysis phase employees from both Hitachi Energy and Energy Thun AG worked out the planning criteria to develop a future grid concept during a joint workshop. In the process the planners were able to draw upon many years of experience as well as a multitude of grid studies which had already been carried out.

The structured approach enabled a clear analysis of the initial situation, upon which the planning criteria to develop the future grid were determined. With these specifications and the experience from the many grid studies already carried out Hitachi Energy’s experts optimized the grid structure while considering the foreseeable development of load and generation. The target was a high quality of supply and at the same time high economic efficiency related to grid costs. Moreover, the developed grid structures were to be disentangled and made leaner. For example, secondary switching stations and lateral axes were put into question in the case of an upcoming need for renewal.

Assessment of the target grid was done by a comparison of reliability and costs between the actual grid and the target grid. In the process consideration was given to the investment required to implement the target grid and the saved re-investments – upon implementing the target grid – due to the absence of operating resources as well as annual costs incurred for both the actual grid and the target grid.

Furthermore, the intake capacity provided by the target grid was quantified for distributed feed ins from PV-plants.

The customer benefit

Together with Energy Thun AG Hitachi Energy’s grid planners have set the course in this project for the future development of a 16kV grid. The implementation measures were comprehensively documented in a geographical plan. Additionally, general-purpose planning criteria which will be applied during future planning at Energy Thun AG were determined.

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