Analysis of Self-Excitation in Turbine-Generators Induced by Static Blocking Filter

In the Tuoketuo project in North China, a phenomena of system destabilization was impressively recognized during the field test of the subsynchronous resonance (SSR) mitigation device, static blocking filter (SBF). This paper, with the test of the SBF device in the Tuoketuo project as the background, presents a comprehensive analysis to the nature of the system instability. The instability behavior is firstly validated by PSCAD/ EMTDC simulation. Through insights into the mechanism of the phenomena, the instability is then determined as self-excitation in generators induced by SBF. To further investigate its characteristics, eigenvalues approach is adopted to analyse the effect of the SBF in-service and the sensitivity of self-excitation to generator parameters. Finally, possible countermeasures are proposed to mitigate this kind of self-excitation.