Self-Excited Oscillations in a Transmission System Using Series Capacitors

Self-excitation can result from using series capacitors in EHV transmission circuits if the series compensation is large and the circuit resistance small. Such a condition can be realized in a highly compensated transmission line using bundle conductors. An analytical approach to solve for the borderline conditions between stability and instability is presented. The analysis presented is suitable for the simultaneous consideration of both electromechanical (hunting) and primarily electrical (self-excitation) oscillations using lumped circuit constants, or for cases of distributed circuit parameters (long lines and/or solid-rotor generators). Numerical examples are included.