Electric power grid structural vulnerability assessment

With the rapid development of economy and the increasing interdependence between national infrastructures, power system is becoming more and more complicated. Moreover, because of the deregulation of power system and the impact of power market, the deteriorated natural environment and the potential terrorism attack, power system is facing with more challenges and becomes more vulnerable than ever. So, It is necessary to assess the vulnerability of the power system, to identify the vulnerable parts so that to provide reference to protect the critical assets, develop the response to the unpredicted incidents, promote the awareness of the operators, standardize the procedure of operations and assure the safety and stability of power systems. Vulnerability assessment is a systematic project, and different methods lead to different results. The structural vulnerability of electric power grid discussed in this paper is to ascertain the ability that the system keeps integral and operates within the constraints in occasion that series equipments failed and out of service. As a common instance, node vulnerability and plain vulnerability are defined, as well as four kinds of structural vulnerability indices are defined respectively according to the violation of system limit, system adjustment, possible loss of load and sensitivity of the power on transmission line to the line impedance.