The distribution systems are usually of high complexity with a large system scale and varieties of load types. Moreover, they are also expanding at an unbelievable rate in terms of complexity. The world faces a significant investment challenge to build, expand or improve the electrical power systems to meet the continuous increasing loads.

Meanwhile, power system operation process often encounters a significant and growing demand for the connections of renewable energy systems such as solar panels, wind-turbines, micro-turbine generators and so forth.

Nowadays in the smart grid application area, intelligent algorithms are widely utilized to control the distribution systems with complicated topologies. However, there is a huge gap between the application area and theoretical field. Although highly automated and integrated control systems have been proposed, systems with coverage from the zone substation to the middle-voltage (MV) feeders practically do not exist.

By researching the basic structure of active distribution networks, this study is aimed to propose a hierarchical optimization strategy that is feasible to fully exploit the capabilities of both traditional and emerging devices, expand the network load capacity and accommodate more renewable resources connections.