Abstract: The large-scale grid connection of renewable energy with strong randomness and volatility and the

net load fluctuation caused by time sequence put forward higher requirements for the operation flexibility of power

system. In order to quantitatively evaluate the operation flexibility capacity of power system，a mathematical model

for operation flexibility evaluation of power system based on two-stage robust optimization method was proposed.

In the first stage，it is assumed that the output of renewable energy is determined，and the objective function is

based on the minimization of operation cost，air abandonment and load shedding. In the second stage，adjust the

operation scheduling strategy in the first stage according to the uncertainty of renewable energy output.

Constructing a class of adjustable robust sets to characterize for uncertain factors. The dual theory and big M

method（Big-M）were used to transform the model into a solvable optimization model. The column-and-constraint

generation（CCG）algorithm was introduced to solve the model，and numerical simulation was carried out on the

improved IEEE RTS 24 bus test system to verify the effectiveness of the evaluation method.

      Key words: two-stage robust optimization model；flexibility assessment；flexibility capacity；column-andconstraint generation（CCG）algorithm