Reducing network expansion using AC and DC meshing concepts

The strong increase of wind energy and photovoltaic systems (PV), which are mainly connected to the medium voltage (MV) and low voltage (LV) level, leads to corresponding network expansion demands and thus to significant investment costs. In the context of this publication, it is investigated to what extent different concepts for dynamic meshing in the MV level can contribute to a reduction of the network expansion demand. The concepts under investigation are the change of topology in existing grid structures by closing switches at open ring network stations (AC meshing) and the alternative application of medium voltage direct current (MVDC) technology as a back-to-back application (DC meshing). The investigation was carried out for a rural, a suburban and an urban MV grid in order to test the advantageousness of the two concepts for different grid types and thus supply tasks. The results of the study show that both concepts can lead to significant savings in the needed network expansion, with the integration of a back-to-back MVDC being more effective than AC meshing. However, the result is not evaluated against the expected investment costs of AC meshing and MVDC applications. Thus, an economic evaluation still must be carried out in future work.