I. Introduction
At present, the development of power grid in China is changing from a high-speed to a high-quality stage, and at the same time, also from a well-off power grid focusing on power supply reliability and power quality to a modern power grid considering economy and coordination [1 – 3]. The power grid is now entering a stage of large-scale utilization of clean energy focusing on intelligent grid [4], presenting both new features and new challenges:
Both extreme light and heavy load problems exist in power grid, it is therefore urgent to improve the quality and efficiency of the grid;
On the other hand, some planning districts are faced with the problem of power supply coordination during the process of grid transition;
In addition, the efficiency problem of the power grid aroused from the expiration of the service life, the decommissioning of the used equipment and the alteration between the new and used equipment;
The national macro energy policy is greatly supporting the development of new energy and energy storage with the proportion of new energy power increasing and the number of supporting energy storage demonstration projects adding, thus resulting the complexifying factors and heavy tasks during the planning.