frequency responses are only shown for a single parameter set for each controller, but it is clear that the tuning of the controllers will impact the resulting frequency responses. In both Fig. 5 and 6 the frequency responses for reactive power and power factor control overlap and it is not possible to distin-guish between the curves for these controllers. The frequency response for the voltage control is fundamentally different from that of the reactive power and power factor control. For frequencies below 1 Hz, reactive power control and power factor control show a response that varies for different SCRs, whereas much less variation is noted using voltage control. For higher frequencies, i.e. > 1 Hz, the transmission delay dominates the phase response with an increasing phase lag.