  Compared with relational database (RDB), graph database (GDB) is a more
intuitive expression of the real world. Each node in the GDB is a both storage
and logic unit. Since it is connected to its neighboring nodes through edges,
and its neighboring information could be easily obtained in one-step graph
traversal. It is able to conduct local computation independently and all nodes
can do their local work in parallel. Then the whole system can be maximally
analyzed and assessed in parallel to largely improve the computation
performance without sacrificing the precision of final results. This paper
firstly introduces graph database, power system graph modeling and potential
graph computing applications in power systems. Two iterative methods based on
graph database and PageRank are presented and their convergence are discussed.
Vertex contraction is proposed to improve the performance by eliminating
zero-impedance branch. A combination of the two iterative methods is proposed
to make use of their advantages. Testing results based on a provincial 1425-bus
system demonstrate that the proposed comprehensive approach is a good candidate
for power flow analysis.
