In order to enhance the ability of load transfer of the new meshed network and improve power supply reliability while reducing cost

this paper presents an integrated methodology for expansion planning of the active distribution network based on the particle swarm optimization (PSO) algorithm. The method proposed deals with the coordinated planning of distributed generator (DG) units and a meshed distribution network with multiple power supply paths by taking into consideration the uncertainty related to renewable DG output power. A multi-objective optimization model is proposed considering economic efficiency

reliability and stability. Double nested PSO is used to solve the optimization problem. The siting and sizing of four types of DG

including wind power

photovoltaic solar energy

gas turbine and energy storage battery are reviewed. Uncertainties related to demand and power supplied by DG units are represented through multi-state probability models. Then in each state

the expectation of output power is used instead of random values. The rationality of the method proposed is verified by results concerning an actual test system in a certain development zone.