Prospective single and multi-phase short-circuit current levels in the Dutch transmission, sub-transmission and distribution grids

As elsewhere in the world, also in the Netherlands utilities face an increase in the actual and future short-circuit current levels at all voltages. This development is provoked by the required increase in transmission capacity as well as the concentration of power generation capacity. Large electricity production sites are moved to peripheral locations, thus overstressing the local transmission networks with respect to both the transmission capacity and the short-circuit power withstand capability. Dispersed power generation facilities, like windmills and co-generation plants for greenhouses, tend to appear in the same (optimal) neighborhoods, thus overstressing the local distribution and subtransmission networks. In the paper the development of short-circuit currents in the Dutch 400 kV-grid is illustrated. In addition, some particular aspects of the short-circuit currents will be addressed: three-phase and single phase fault currents, DC-time constants, peak values, contributions from transformers and distributed generators. Practical calculation guidelines on the actual short-circuit contribution from generators will be given. An example of design of a 400 kV station extension, emphasizing short-circuit current considerations is evaluated. National and international trends are addressed. More severe specifications of substation equipment lead to adapted designs and adequate testing procedures. Examples from testing of the consequences of short-circuit currents and fault arcs of 80 kA and above are highlighted