Enhanced grid frequency support by means of HVDC-based load control

The two major frequency incidents in Continental Europe and UK call for faster frequency regulation. Hvdc systems can dynamically adjust the power output to support the frequency regulation by means of droop characteristics. Adding derivative terms in the power controller enables inertia emulation that improves the system initial response. As drawback, due to the fast power transfer variation, the HVDC-connected areas suffer from temporary power imbalance and hence frequency deviation. To overcome this limitation, HVDC-based load controllers can be implemented at HVDC terminals to shape the consumption of nearby voltage-sensitive loads by means of controlled voltage variations, with the goal to minimize the frequency deviation in the supporting areas. In multi-terminal systems, the frequency support can be optimally shared among terminals depending on the load sensitivity. This minimizes the voltage deviation in supporting areas and limits the hvdc reactive power, while providing the same frequency damping in the faulty area.