A mixed integer second-order cone programming(SOCP)model for active distribution network(ADN)expansion planning is proposed

which minimizes the total investment and operation cost. Four active management strategies consisting of on load tape changer(OLTC)tap adjustment

distributed generator(DG)curtailment

load curtailment

and reactive power compensation are considered to cut the planning cost and future operation risks of the planning. The planning model allows alternatives to be considered for active management

new wiring

new substation

substation expansion and DG installation. The distribution network planning(DNP)problem is a mixed integer nonlinear programming problem. What with the active management and uncertainties

the DG integration has made the DNP problem considerably complicated. In order to find a polynomial time computable model

the DNP problem is converted to a SOCP model through power flow equations and constraint relaxation. A modified IEEE 33-bus system and Miranda 54-bus system are used to testify the proposed model. This work is supported by National High Technology Research and Development Program of China(863 Program)(No. 2014AA051901)and State Grid Corporation of China(No. 52094015000A).