A Multi-level And Multi-aspect Identification Method Of Critical Lines Considering The New Regulation For The Investigation Of Electric Power Accidents

With expansion of the scale of power grid and increasingly complexity of network structure,the operation security of power grid has induced great attention from government,company and academia.Using reasonable method to identify the key lines of power system is of great practical significance for the early detection of potential risks and the maintenance of social interests.This paper proposed a multi-level and multi-aspect identification method of critical lines considering the new rules for the investigation of electric power accidents.The core and purpose of this method is the find the critical lines by using risk theory as one of the methods,based on the identification of critical nodes.The model responded the new rules about loss of load requirements,considering technology standard of safety risk assessment in China Southern Power Grid and relationship between critical nodes and critical lines.The paper proposed comprehensive identification model of critical nodes based on the new regulation.The identification index system was constructed from the view of individual,local and global attributes,considering the difference between the load level and node itself.The utility theory was used to normalize the sub indexes,which avoids the shadowing effect and increases the identification effect.The subjective and objective combination weights of the sub indexes were obtained by using cooperative game theory,which can avoid the error caused by the single weight method.Finally taking IEEE-39 bus system as an example,the rationality,feasibility and superiority of the model were illustrated by comparing with existing classical research methods.Risk assessment model was established based on the new regulation,the critical nodes and the environmental impact factor.First the induced ordered weighted averaging operator was used to predict the forced outage rate of transmission lines.Combined the predicted rate with line load rate,weather conditions and equipment defects to make it more close to the actual situation.Then put forward the voltage deviation index based on the critical nodes,the load loss severity index considering load level and the weighted entropy of power flow index to measure the disconnection consequences of lines in response to the requirements of new regulation.Taking into account the social background conditions,the environmental impact factor of power supply was defined to correct the risk results.And the fuzzy comprehensive evaluation was used to achieve hierarchical management.Finally the example of IEEE-39 bus system proved the reasonable and feasible of the model.The paper also analyzed the relationship between the risk level and the load level.At last,the paper considered the relationship between critical nodes and critical lines,and put forward amulti-level and multi-aspect critical line identification method.Taking the IEEE-39 bus system as an example,the rationality and feasibility of the method are analyzed from the view of the structure,the state and the risk.This method can identify and sort the critical lines from different aspect according to the requirements of relevant personnel,which has great theoretical value and practical significance.