Vulnerability evaluation of power system integrated with large-scale distributed generation based on complex network theory

As the most wide-area industrial network, the power system can be modeled as a graph with edges and vertices, which represent the lines and buses of the power grid respectively. Further methodologies such as complex network theory may help in identifying the vulnerability of power grid, analyzing the contingency, preventing cascading blackouts and so on. When power system is integrated with distributed generation (DG), decentralized generation at distribution level replaces some of the centralized generation at transmission level. DG units are able to improve the reliability of the power system, shorten the electrical distance between the sources and loads, alleviate the long-distance large-capacity transmission, and increase the efficiency. This paper proposes several vulnerability indices, such as structural vulnerability index (SVI), contingency vulnerability index (CVI) and operational vulnerability index (OVI) to evaluate the impact of DG to power system vulnerability. The simulation in DIgSILENT/PowerFactory is conducted to assess the vulnerability of a 93-bus test power system, identify the vulnerable lines and buses, evaluate the improvement of the vulnerability index when the network is integrated with DG units, and may further to optimize the planning DG units in the future.