Design of Volts per Hertz limiter with consideration of the under-excitation limiter control actions

The dynamical relationship between the Volts per Hertz limiter and the under-excitation limiter control loops in a synchronous generator is examined using the frequency response technique. From the analysis, it is concluded that sustained oscillations due to the interaction between the two limiters can occur should the loading level of the generator exceeds a certain threshold value. For generator operation below this value, a systematic design procedure has been proposed for the limiters which will ensure network stability.