Approaches for dealing with increasing short-circuit currents in transmission systems

Inhalt:
One of the most important aspects of planning of electrical installations is the consideration of short-circuit withstand and breaking capability. In that term, proper dimensioning of the equipment requires thorough investigation of both current and future scenarios in order to select a grid condition deemed relevant for selecting the required properties. Since the structure of the electrical systems is undergoing constant changes, both in the areas of generation and transmission/distri-bution of energy, it is crucial to follow these changes and develop planning strategies being able to cope with the upcoming challenges. This paper presents the forecasted development of the short-circuit level in the control areas of two German TSOs: Amprion and TenneT. The main focus lies on identification of the reasons for the increased short-circuit level – giving an insight into dependencies between the grid development and the value of short-circuit current at the considered substations. Mitigation methods are described, with pros, cons and feasibility of the suggested solutions. The given ex-amples have the goal to illustrate the necessity of developments both in terms of grid planning and future proof equipment manufacturing.