With large scale clean energy integrated into power grid, the intermittency and randomness of output power exert obvious influences on real time economic dispatch. This paper proposes preventive security constraint robust optimal power flow method considering mixed constraints filtering. In this method, an affine adjustable robust optimal power flow model is proposed and the preventive security constraints are also considered. In the solution procedure, mixed constraints filtering technique is adopted to reduce problem scale. Several tests on different systems are conducted to prove the effectiveness in real time economic dispatch considering uncertainty. This work is supported by National Natural Science Foundation of China (No. 51507031) and Science and Technology Project of Jiangsu Electric Power Company (No. J2018064 and No. J2018069).