The development of DC technology provides a new way to deal with overload

voltage over limit and imbalance issues caused by high-penetration electric vehicles (EV) in distribution systems (DS). To cope with the increase of EV charging load

this paper proposes an AC-DC hybrid DS expansion planning scheme including the upgrade of charging stations (i.e.

from slow charging station to fast charging station). Firstly

the planning constraints incorporating DS topology variables are derived and the three-phase power flow model is utilized to describe imbalance situations in DS operation. Secondly

the deterministic AC-DC hybrid DS expansion planning model with the objective of minimizing investment cost and operation cost is presented. Thirdly

considering the uncertainties in EV charging load and DG output among different periods

the multi-stage stochastic programming model is established and the stochastic dual dynamic integer programming algorithm is applied. Finally

case studies on modified IEEE 33-and 141-bus DS are proposed to verify the effectiveness of the proposed method.