Prevention Strategy Of Improving The Safety Level Of Power Grid For Cascading Tripping

The development of society is increasingly dependent on electrical energy,and the construction of the power grid is also growing.Complex interconnected power grids are not only convenient for people,but also suffer from blackouts caused by cascading failures.Blackouts in recent years not only affect people's normal work life,but also bring huge economic losses.Therefore,defending cascading failures is an important topic in power grid research.From the analysis of grid cascading failures,there is a strong correlation between cascading tripping and cascading failures.The early stage of cascading failures usually appears as cascading tripping.In order to avoid complex cascading failures,measures should be taken at the early stage to avoid cascading tripping,which is very helpful for preventing cascading failures.The research focus of this article is to resist cascading failures by preventing cascading tripping and to study how to improve the system's ability to defend against cascading tripping.First of all,from the perspective of relay protection,the mechanism of the occurrence of cascading tripping is analyzed,and whether or not the branch trip occurs is determined by judging the electrical distance between the branch operating parameter and the relay protection value after the initial fault occurs.On the basis of the method of judging the occurrence of cascading tripping,the electrical distance between the system and the occurrence of a cascading tripping accident is used as the evaluation index of the safety level of the system for cascading tripping,and the specific calculation method is given.Then.The influencing factors of safety level evaluation index are analyzed,and it is found that the unit output before initial failure has an impact on its numerical value.The safety level of the system will change if the unit output changes.On the basis of the above work.this paper gives the prevention strategy of the defense cascading tripping.This strategy is an optimization model based on the optimal target of the safety level evaluation index and the allocation of unit output as the optimal variable.Based on particle swarm optimization,a solution method of the optimization model is proposed.Further,an improved algorithm based on particle swarm optimization is applied to optimize the algorithm.Finally,the simulation verification is carried out by an example analysis.Through this study,it can be found that optimizing the unit output can effectively improve the safety level of the system defense cascading tripping,and then availably prevent the cascading tripping accident.