Microgrid is an organic system which consists of loads and micro-sources (distributed system which generations, consists DG) and energy storage devices. Microgrid can effectively integrates variety of new energy generation technologies; can
make economic and environmental benefits by using new energy power generation; can better meet the requirements of
customers for higher power quality and reliability of power supply; can achieve peak load shifting of power grid, and can
improve the utilization ratio of energy [1-3].
The optimal operation of the microgrid is a crucial and difficult problem, which caused widespread concern. The
characteristics of microgrid's optimal operation are listed as followed:
a) Since the microgrid is mainly connected to distribution network, the voltage level is low and the resistance of the
transmission line system plays the dominant role, line loss cannot be ignored [4];
b) New energy generations such as wind power and photovoltaic power are affected by the natural environment