.PowerSystems.AC3ph.ImpedancesYD

Information

Contains lumped impedance models for Y and Delta topology.

General relations see 'Impedances'.

All elements allow the choice between Y- and Delta-topology.
The impedance parameters are defined 'as seen from the terminals', directly relating terminal voltage and terminal current. With this definition same parameters lead to same network properties, independent of topology. The necessary scaling is performed automatically.

In Delta-topology the conductor voltage is sqrt(3) higher, the current sqrt(3) lower, compared to the terminal voltage and current. Therefore the impedance relating conductor current and voltage is a factor 3 larger, the admittance a factor 1/3 smaller than the impedance and admittance as seen from the terminal.

If impedance parameters are known for the WINDINGS, choose:

  input values impedance parameters = (winding values of impedance parameters)/3

In dq0-representation the following relations hold between
terminal-voltage term.v and -current term.i on the one hand
and conductor-voltage v and -current i on the other:

Y-topology:

  v = term.v - {0, 0, sqrt(3)*v_n}: voltage between terminal and neutral point
  term.i = i
  i_n = sqrt(3)*term.i[3]

Delta-topology:

  v[1:2] = sqrt(3)*R30*term.v[1:2]: voltage between phase-terminals
  v[3] = 0
  term.i[1:2] = sqrt(3)*transpose(R30)*i[1:2]
  term.i[3] = 0

with R30 = rotation_30deg
(Alternative solutions corresponding to permuted phases are R-90 and R150 instead of R30).

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