With the increase of power output fluctuation on the source side and the continuous increase of power demands on the load side

the static voltage security boundary becomes the main factor of limiting the increase of loads and leading to insufficient adequacy. In order to improve the system adequacy and avoid load loss

this paper proposes an adequacy enhancement method that considers the relaxation of the static voltage security boundary. Firstly

the Continuation Power Flow (CPF) method is used for static stability margin analysis to describe the static voltage security boundary and limit boundary; meanwhile

according to the obtained residual load margin as the sufficiency index

the critical voltage nodes are identified for selective security boundary relaxation. Secondly

the risk of security boundary relaxation is described by calculating the probability of voltage breaking the limit boundary due to load uncertainty fluctuation after relaxation and taking preventive control measures to solve the product of the minimum cost of voltage recovery. Finally

the IEEE39-node system is used for simulation analysis

and the results of the numerical example verify the effectiveness of the proposed method.