Short-Circuit Calculation in Distribution Networks with Distributed Induction Generators

Abstract

This paper presents an improved current source equivalent model method to determine the short-circuit current of a distribution system with multiple fixed-speed and variable-speed induction generators (IGs). The correlation coefficients of flux components between stator and rotor under the unsymmetrical fault are analyzed using the positive and negative sequence steady-state equivalent circuits of an IG. The terminal voltage and current responses of fixed-speed and variable-speed IGs with and without the rotor slip changes under different penetration levels are compared to investigate the coupling relation between the short-circuit currents of IGs and the nodal voltages in the distribution network. Then the transient equivalent potential of an IG at the grid fault instant is derived. Sequence components of the short-circuit current in the network can be determined using the proposed technique. The correctness of the proposed method is verified using dynamic simulation.

A validation approach for short‐circuit currents calculation in large‐scale power systems

“…Taking this into account, as well as mentioned problem of numerical modeling of large-scale EPS, all validation experiments of SCC calculation results are currently performed using software tools of electromagnetic transient calculation, which are used as reference for small test scheme and are not used for large-scale EPS. [37][38][39][40] Moreover, the research 41 proves that the calculation results obtained for the test scheme are not applicable for large-scale EPS. Therefore, validation of processes calculation, especially of SCC, for large-scale EPS is important task to ensure EPS operation stability, but currently, it is insufficiently studied.…”

“…This fact is confirmed by the performed studies analysis. Taking this into account, as well as mentioned problem of numerical modeling of large‐scale EPS, all validation experiments of SCC calculation results are currently performed using software tools of electromagnetic transient calculation, which are used as reference for small test scheme and are not used for large‐scale EPS . Moreover, the research proves that the calculation results obtained for the test scheme are not applicable for large‐scale EPS.…”