A new concept of schedulable ability(SA)is proposed to represent the ability of dynamic and two-way energy balance for electric vehicles(EVs)in a certain distribution network

with a priority-based intraday scheduling optimization model for EVs built. Firstly

the SA model is formulated to analyze SA of EVs quantitatively

which takes battery loss

customer's credit and discharging capability of EVs into account. Secondly

based on an analytic model of SA and two-stage supply-demand coordinated optimization method for EVs

the optimal threshold value of SA for EVs is obtained to minimize the peak-valley difference of distribution system load considering customer's driving habit. Finally

the scheduling priority of EVs is determined by numerical comparison between its SA assessment result and the optimal threshold value of SA

thus creating the priority-based intraday scheduling strategy for EVs on the event-driven basis. A certain residential district is taken as an example to show the rationality and effectiveness of the proposed optimization model. This work is supported by National Natural Science Foundation of China(No. 51507153)and Zhejiang Provincial Natural Science Foundation of China(No. LY16E070005).