Abstract: In order to compensate the decreasing frequency stability control resource caused by the large-scale integration of the renewable energy in the power system, a chance-constrained optimal configuration scheme considering the time-of-use price and the maximum transient frequency deviation（MTFD）is proposed for the energy storage system（ESS）. Firstly, an extended system frequency response model is established to estimate the frequency dynamic response characteristics under the predefined contingency, from which the constraints of MTFD are extracted by the max-affine function based piecewise linearization method.Secondly, taking into account the uncertainty of contingencies, a chance-constrained optimization model is built to optimize the capacity of the ESS, with the objective of minimizing the investment cost and maximizing the peak-valley arbitrage income.Thirdly, the linear weighted method and the Monte Carlo-and nonlinear decreasing inertia weight-based particle swarm optimization algorithm are used to attain the optimal capacity of the ESS. Finally, a case study is carried out to validate the effectiveness of the proposed method.