Research Paper No 8: Subsynchronous resonance of the Koeberg turbo-generators and of a laboratory micro-alternator system

The paper presents the results of in investigation into the subsynchronous resonance (SSR) behaviour of the 1 072 MVA nuclear powered turbo-generators to be Installed at Koeberg Power Station. A mathematical model describing the dynamics of the shaft system, the synchronous generator and the transmission network is presented. An eigenvalue analysis of a linearized model and the Fourier transformation of some of the time domain waveforms provide insight into the physical mechanism of SSR. The mathematical model is checked by measurements on a laboratory micro-alternator and transmission line simulator system. The results show that unless precautionary steps ere taken, unstable subsynchronous oscillations could occur at Koeberg.