In traditional power grid planning, only one of the economy and security risk is focused. With that irrationality, the security risk is translated into available transfer capability and added in the objective function. Then, a planning model considering both invest cost and available transfer capability is proposed, to maximize the comprehensive benefits. Finally, an improved niche genetic algorithm, which is used to solve the planning model and then the corresponding optimal scheme is obtained with different wind power penetration. The effectiveness of proposed model and algorithm are verified by case study.