Abstract: The integration of high proportion of wind power intensifies the uncertainty of power system

operation. The sufficient flexibility is vital for the safe and reliable operation of the power system. An evaluation

method of power system flexibility considering wind power prediction interval was proposed. First，considering the

stochastic fluctuation and prediction interval of wind power，a stochastic extreme scenario set was constructed，

which can characterize the uncertainty of wind power generation and slope climbing，and reduce the complexity of

the problem. Then，considering the operating characteristics of units and power system，the comprehensive

evaluation indices of operational flexibility of units and system were proposed. Finally，in view of the system cost

constraints and the operating constraints under the forecast and stochastic scenarios，the flexibility optimization

evaluation model considering the wind power forecast interval was established to quantify the flexibility supply

capacity of units and system，so as to effectively ensure operational robustness. Simulations on the improved IEEE

39 bus system were carried out to verify the feasibility and effectiveness of the proposed method.

      Key words: wind power；uncertainty；prediction interval；extreme scenario；power system；flexibility；flexible

resources；evaluation index