Earthing Study for ewz

Submitted by daegerte on Thu, 04/20/2017 - 21:55

The aim of the study was to investigate the effects of the introduction of an impedance grounding of the transformer star points on the 150 kV high-voltage grid and the substations under the following questions:

  1. Appropriate size of the impedances for setting the short-circuit current in accordance with the requirements of the protection concept
  2. Effects in operation and in various errors and necessary fault shutdown times
  3. Effects on the insulation coordination, increase of the earth-fault factor, changes in the fault transients and switching transients
  4. Estimation of the risks due to the short-term shift of the star-point voltage for the high-voltage devices
  5. Effect on the grounding systems of the substations and on possible ohmic and electromagnetic influences

The short-circuit calculations were done using a extensive model of the 150 and 11/22 kV power grid in Neplan.