Abstract: The failure of the commutation at the inverter side of the new energy through the high-voltage DC external transmission system may lead to the transient overvoltage problem of the sending end system. As one of the dynamic voltage support devices, the synchronous condenser can effectively improve the voltage support strength of the power grid, which has received widespread attentions in suppressing transient overvoltage and speeding up fault recovery. Aiming at the problem of suppressing the transient overvoltage by using distributed synchronous condensers, this paper first analyzes the influencing factors of power grid strength based on the multiple renewable energy station short circuit ratio. Then, the influence of the condenser access on the power grid parameters and intensity is studied. The gray correlation analysis is used to calculate the degree of correlation between the influencing factors and the power grid strength. Then, taking it as a weight, an α index is proposed for the capacity allocation of the condenser that comprehensively considers the influence of each electrical parameter. Finally, taking the α index and the overvoltage levels as constraints, the distributed synchronous condenser capacity configuration scheme is studied. The electromechanical transient simulation is used to verify the correctness of the condenser capacity configuration scheme from the two aspects of economy and effectiveness.