The fluctuation of renewable energy generation brings challenges to voltage stabilization and optimal power flow. As a flexible electronic device, the electric spring (ES) can form a smart load with its connected non-critical load, which provides voltage support and mitigates power congestion to ensure safe and reliable operation of the distribution network. Considering the uncertainty of renewable energy resources, this paper proposes a two-stage robust optimization model for ES allocation to reduce the transmission power congestion. Subsequently, due to the nonlinear nature of ES modeling and power congestion, McCormick envelope and conic relaxation methods are performed to reformulate this model as a mix-integer second- order cone programming problem. Moreover, the column-and constraint generation algorithm is employed to solve the proposed two-stage power congestion optimization problem. Numerical results on a modified IEEE 33-bus distribution network demonstrates the effectiveness of the proposed robust ES allocation scheme.