Transient study of two 500 kV coupled lines in a transient network analyzer

Modern transmission systems require adapting old networks to new schemes with major operation flexibility. Frequently, the new operation states may lead the equipment out of the design conditions. This paper shows switching transient studies, carried out over an old system, to improve its performance. The disconnection of one section of the system, due to power flow requirements, produce resonance between two parallel lines. A transient network analyzer was used to study the system of two unbalanced-coupled 500 kV lines, saturable reactors, transformers and series capacitors. Main problems and results have been included.