Identification Of Vulnerable Links In Power Grid Based On Active Power Flow Betweenness

In recent years, several large-scale power outages occurred in the world. The failure of a running component may lead to the power flow moving in a large scale, partial lines overload and trip, voltage collapse and then the occurrence of cascading failures.The occurrence of cascading failures shows that the power network is still fragile. In view of these vulnerable links, corresponding protective measures effectively reduce the risk of cascading failure, prevent the occurrence of large area blackout, and improve the operation reliability of the system. Therefore, it is important to accurately identify the vulnerable links of power networks and then eliminate the potential risk of system under different operation modes. The research contents of this paper include the following three aspects:First of all, this paper introduces the three methods used in the study of vulnerability of power network, namely the state vulnerability assessment method, the structural vulnerability assessment method and the comprehensive vulnerability assessment method.This paper focuses on the complex network theory method in the structural vulnerability assessment method. The actual distribution of the power flow and the capacity of each transmission line are involved in the model which is more comprehensible to the physical backgrounds of power system. To improve the recognition accuracy, the indicator of active power flow betweenness is proposed in the model. The actual distribution of the power flow and the capacity of each transmission line are involved in the model which is more comprehensible to the physical backgrounds of power system. The experiment on IEEE-39 bus system and IEEE-118 bus system shows that a few high active power flow betweenness lines play a vital role in the power transmission grid. Vulnerable lines in the power network are mostly the key link lines or the lines with high power flow. Continuous attacks against these high active power flow betweenness lines have a great impact on the overall topology and operational status of the network.Secondly in this paper, the system transmission efficiency index and the power transmission efficiency index are used to verify the effectiveness of the identification results of vulnerable links. The change of power transmission efficiency of the system is simulated by the methods based on random attack, the electric betweenness attack and the active power flow betweenness attack. The results show that the continuous attack to the lines with high active power flow betweenness can lead to a dramatic decrease in thepower transmission efficiency. The downward trend is much faster than the other two kinds of perturbation methods. The validity of the critical lines identified by the active power flow betweenness model is verified from the other point of view.Finally, the influence of the access of new energy on the identification of the vulnerable link of the power network is analyzed in this paper. The vulnerable links identification results of the IEEE-39 bus system with new energy show that the local energy supply-demand relationships can be improved, the importance of related link lines become weakened. Comparison between the system with new energy access and no new energy access shows that the system anti-interference is enhanced with certain new energy capacity access.