Identification of Vulnerable Lines in Urban Power Grid Based on Voltage Grade and Running State
Yong Cai · Proceedings of the CSEE · 2014
Critical lines have serious impacts on large scaled blackouts and on cascading failures in urban power grids. Considering the state of power grids, a new concept of power flow entropy based on entropy theory was introduced to quantitatively describe the unbalanced distribution of power flow. Then the paper proposed the changing of flow entropy as a vulnerability index to see the variation of load distribution due to any lines removed. Based on the complex network theory and topological characteristics, the index of node-important was defined which is corrected by factors according to the voltage grade and location of geography. Thus, the identification of vulnerable lines includes the changing of flow entropy, voltage excursion, node-important and correcting factors. Vulnerability analysis was carried out on the Changsha urban power grid, operational plan on summer, 2011, and the time-domain simulation results verified that the index this paper proposed can identify critical lines in accordance with the real systems, especially can find which line has light loads but has great impacts on vulnerability due to their special position in the power grid. Simulation on IEEE 39-bus system proves that the proposed method is reliable.