To help power enterprises further understand the potential economic benefits from application off ault current limiter（FCL） and accelerate the promotion of FCLs in power grids

the concepts of reliability cost and reliability benefit are defined from the view point of using FCLs to improve the dynamic and thermal stability and operational reliability of the circuit breakers. The life cycle cost of an FCL is regarded as reliability cost. The outage loss difference caused by the change of the rejection probability of the circuit breaker before and after the FCL access is regarded as the reliability benefit. Considering the time factor of capital

the FCL economic evaluation index based on reliability and the comprehensive economic evaluation model of power grid are established

and the proposed model is simulated on Anhui power grid.The model may provide economic and technical reference for engineering application of FCLs.