Open AccessVoltage stability assessment accounting for non‐linearity of Thévenin voltages
Author(s) -
Karatas Bahtiyar C.,
Jóhannsson Hjortur,
Nielsen Arne Hejde
Publication year - 2020
Publication title -
iet generation, transmission and distribution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 110
eISSN - 1751-8695
pISSN - 1751-8687
DOI - 10.1049/iet-gtd.2019.1774
Subject(s) - voltage , instability , electrical impedance , control theory (sociology) , computer science , impedance matching , transformer , tap changer , electrical engineering , engineering , mechanics , physics , control (management) , artificial intelligence
This study presents a new method that overcomes the limitations of previous Thévenin equivalent methods used for detecting voltage instability. The new method determines the maximum deliverable power to a load by accounting for the non‐linearity of the Thévenin voltage seen from a load. The developed algorithm computes Thévenin equivalents seen from voltage‐controlled and non‐controlled nodes to determine how much load changes influence the contributing generators to a load. The algorithm computes an active load margin which gives information about the distance to instability. Tests are performed on the modified Nordic32 system, where the on‐load tap changer mechanism of transformers was the driving force causing voltage instability that leads to small‐signal rotor angle instability. The results demonstrate that the proposed method accurately detects voltage instability compared to the method based on the Thévenin impedance matching criterion, which first detects instability when the system conditions have crossed the critical boundaries.