This presentation will outline a number of different approaches for enhancing transmission system planning for low inertia grids by including stability constraints in within the planning process. Special attention will be given to low inertia systems, and how energy storage and flexible power transmission equipment, HVDC transmission in particular, can help to improve the stability of the system, while decreasing the need for classical sources of system inertia, e.g., synchronous machines. The presentation will show how interzonal exchange of energy by means of virtual inertia can decrease the total operational cost of the system by a quantitative analysis applied to the national electricity network in Australia. Providing an outlook some future grid concepts for renewable dominated power systems will conclude the talk.