Impact of delays on a consensus-based primary frequency control scheme for AC systems connected by a multi-terminal HVDC grid

This paper addresses the problem of sharing primary frequency control reserves among non-synchronous AC systems connected by a multi-terminal HVDC grid. We focus on a control scheme that modifies the power injections from the different areas into the DC grid based on remote measurements of the other areas' frequencies. This scheme is proposed and applied to a simplified system in a previous work by the authors. The current paper investigates the effects of delays on the control scheme's effectiveness. The study shows that there generally exists a maximum acceptable delay, beyond which the areas' frequency deviations fail to converge to an equilibrium point. This constraint should be taken into account when commissioning such a control scheme.