A method of evaluating the transfer capacity for power system considering of the power injection and the power grid topology

The transfer capacity is a varying value for a certain power system, which may be changed with the evolution of the system. Although the topology of a power system is usually designed in an optimizing way to maximize the transfer capability, the capability itself will be inevitably weaken because of a time lag between the increasing load and the enhancement of grid topology. Due to the lack of qualification tools to deal with the varying transfer capability, related topics are seldom to be discussed. This paper proposes a new method to evaluate the transfer capacity, in which the mechanism describing the mismatch can be boiled down to a new index named Spatial Characteristic Length Ratio (SCLR) considering of both the power injection and the power grid topology. By calculating the index SCLR, the transfer capability as well as the factors affecting it can be analyzed, which has an important meaning for power grid planning personnel. The method is used to analyze the transfer capacity of IEEE 4-node system, IEEE 9-node system and IEEE 162-node system, each under different modes of operation. Calculation results has proved the validity of this concept, and the related method is effective.