Multimachine subsynchronous resonance part i — line representation

This paper is the first part of two companion papers which describe a theoretical investigation into the subsynchronous resonance (SSR) behaviour of a multimachine power system. Eigenvalue techniques are applied to the linearized system equations to determine the small-signal stability properties of a case study based on the Koeberg power station in South Africa. The results show that an equivalent single-line representation of two parallel but separately compensated transmission lines is only valid at a single compensation level. The companion paper evaluates the effects of shunt loads, including induction motors, on the SSR behaviour of such a multimachine system.