The Assessment And Improvement Study Of Electricity-gas System Resilience Under Extreme Natural Disasters

As the greenhouse effect intensifies,extreme natural disasters have occurred frequently all over the world in recent years,which poses a serious threat to the normal operation of integrated electricity-gas system.The extreme natural disasters to which the integrated electricity-gas system may be subjected are diverse in type and uncertain in parameters.It is important for planners to comprehensively assess and quantitatively enhance the resilience of integrated electricity-gas system.Therefore,this paper focuses on the resilience assessment and enhancement of integrated electricity-gas system under extreme natural disasters,with the main work including:1.A database of extreme natural disaster scenarios required for resilience assessment is proposed.First,the feasible regions of disaster basic parameters are divided into multiple value intervals,which are combined and enumerated to generate a series of potential disaster scenarios.Then,the weight of each scenario is determined on the basis of the disaster probability model,while the component failure probability group under each potential scenario is calculated by the disaster attack model.The weights and component failure probability groups corresponding to all potential disaster scenarios are integrated into the disaster scenarios database,which is called for resilience assessment.2.An optimal load shedding algorithm for integrated electricity-gas system based on a two-stage gas network optimization model is proposed.The algorithm is based on the decoupling optimization framework and iterates alternatively between the power subsystem and the natural gas subsystem.The gas network optimization part applies a two-stage optimization model: a simplified mixed integer linear model is built in stage1,while a nonlinear continuous model is built in stage 2.The optimization results in stage 1 include real and integer variables respectively.The former provides initial values for the interior point method in stage 2,while the later serves as the fixed input value in stage 2.The proposed optimization algorithm has superior in both model accuracy and computational efficiency.3.A resilience assessment method based on the reusable impact-increment database is proposed.As the intermediate data in the calculation process of the impactincrement state enumeration method(IISE),the impact-increments stay the same in different disaster scenarios.Therefore,this paper constructs a reusable impactincrement database in advance and calculate the expected load shedding under each disaster scenario by repeatedly recalling the impact-increments.In the resilience assessment considering the uncertainties of multi-type extreme natural disasters,the large number of potential disaster scenarios leads to huge time cost for computation,which can be solved by reusing the impact-increment database.4.A resilience enhancement method based on the global sensitively analysis is proposed.First,this paper derives the global sensitivity based on the impact-increment,which is used to quantitatively analyze the joint influence of the simultaneous changes in failure probability of several components on the resilience index.Then,the global sensitivity is inserted into the resilience enhancement optimization models under budget limitation or standard reaching constraint,so as to decide the target components to be strengthened and develop a cost-effective resilience enhancement scheme.The global sensitivity considers the effect of the interaction among different component failure probabilities on the resilience index,which can accurately reflect the resilience enhancement effect of the component strengthening strategy and help to quantitatively enhance the system resilience.