The realization of the dual-carbon goal requires the construction of a new power system with a high proportion of new energy access. The reduction of synchronous machines will inevitably lead to a decrease in the inertia level of the power system

directly affecting the stability of frequency and threatening the safe operation of the power grid. To avoid the power system falling into the predicament of ultra-low inertia operation

it is necessary to scientifically assess the minimum inertia demand of the system

which can be used as the basis for judging the adequacy of inertia. This paper comprehensively reviews the theory and methods for evaluating the inertia demand of the new power system

reveals the energy transfer law of inertia response

points out the nonlinear adaptation contradiction between the dynamic characteristics of power electronic equipment and the frequency stability requirements

summarizes the minimum inertia demand evaluation method based on the dual constraints of frequency change rate and the lowest frequency point

and proposes feasible solutions and lists some engineering examples

providing a new path for the exploration of the frequency stability mechanism and engineering practice of high-proportion new energy power grids.