I. Introduction
With the globally increasing shortage of energy, the diversity of sources and the flexibility of power grid are significantly emphasized in the current power system[l]. Under the background of active distribution network, the increase of installation capacity of distributed energy resources, the rapid development of electric vehicles and the active management of distribution networks (DN) have attracted extensive attention from both academia and network operators[2]. distributed generation and loads (DGL) (also called distributed power supplies and flexible loads) will have different effects on distribution network according to their different position and capacity. The researches show that reasonable planning of DGL will improve the reliability of distribution network, reduce the cost of upgrading and transformation of distribution network, and at the same time produce significant environmental benefits[3],[4]. On the contrary, unreasonable DGL planning and allocation will increase the power penetration of DG, raise the voltage risk, cause the congestion of power transmission and introduce harmonic problems, and then increase the cost of management and maintenance of the whole distribution network. Therefore, making full use of all kinds of schedulable resources and optimizing the position and capacity of the DGL is the key problem related to the reliable and economic operation of the active distribution network[5],[6].