### Abstract

A method for establishing a complex value of the short-circuit
impedance from naturally occurring variations in voltage and
current is discussed. It is the symmetrical three phase impedance
at the fundamental grid frequency there is looked for. The
positive sequence components in voltage and current are derived
each period, and the short-circuit impedance is estimated from
variations in these components created by load changes in the
grid. Due to the noisy and dynamic grid with high harmonic
distortion it is necessary to threat the calculated values
statistical. This is done recursively through a RLS-algorithm. The
algorithms have been tested and implemented on a PC at a 132 kV
substation supplying a rolling mill. Knowing the short-circuit
impedance gives the rolling mill an opportunity to adjust the arc
furnace operation to keep flicker below a certain level.
Therefore, the PC performs a simultaneously measurement of
impedance and flicker.

Original language | English |
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Title of host publication | 32'nd Universities Power Engineering Conference, UPEC'97 |

Place of Publication | Manchester |

Publisher | UMIST |

Publication date | 1997 |

Pages | 453-457 |

Publication status | Published - 1997 |

Event | 32'nd Universities Power Engineering Conference, UPEC'97 - Manchester Duration: 1 Jan 1997 → … |

### Conference

Conference | 32'nd Universities Power Engineering Conference, UPEC'97 |
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City | Manchester |

Period | 01/01/1997 → … |

## Cite this

Nielsen, A. H., Pedersen, K. O. H., & Poulsen, N. K. (1997). Estimating the short-circuit impedance. In

*32'nd Universities Power Engineering Conference, UPEC'97*(pp. 453-457). UMIST.