The Assessment And Theoretical Research Of Power System Vulnerability

With the rapid development of modern power grid, power system interconnection topologies is increasingly tight. On the one hand, it has a high supply capacity, on the other hand, it will easily give rise to wide ranges of flow fluctuations, node voltage loss, circuit overload fault because of component outage, and then let the power system separation. The important transmission lines in the grid is usually plays a vital role in the chain of accidents, which is the stable operation of weak links in the system. Identify network weaknesses in a timely manner, and make the early-warning and maintenance, to improve grid stability and reduce failure of large-scale topology has an important value.In order to identify vulnerable link and ensure the safe operation and risk control of the power system, an improved line’s vulnerability index and assessment method based on reliability theory was proposed. Firstly, the power flow betweenness was constructed according to the electrical betweenness, which was combined with generation node’s dispatch and line’s transmission capacity. Secondly, with a reliability weight coefficient introduced, the improved line’s vulnerability index was established, which was able to identify the critical lines of power grid by means of risk accumulation, network topology’s failure rate and power flow loading capacity. Then, the identification accuracy of the improved index was verified by the transmission level parameter, the experimental results of IEEE 24 nodes system showed that the transmission level of system would plug when the lines with high improved vulnerability index were attacked, which reflected the importance of these lines in power system. Finally, the improved line’s vulnerability index and assessment method were modified and applied to examples under the wind power grid integration systems. Experimental results show that the reasonable location of the wind farm into power system can effectively improve the whole level of network reliability, reduce the cumulative risks and topology the failure rate of the whole network; Wind power will improve system robustness of system. When the power system stability is poor, it makes some segments more vulnerable, due to absorption of wind farm reactive power, improved vulnerability index values and reduction in transmission levels will increase.