Research On Reliability Assessment Of Dower Grid Considering The Reliability Of Towers Under Different Disaster Conditions

With the increase of the national economy,the scale of the electric power system is correspondingly expanded,the economic loss and social influence caused by the failure of the power system are increasing,and the importance of its safe and stable operation is also significantly enhanced.In recent years,a number of natural disasters have put the power grid under severe test.For example,in some areas of southern China,long-duration,high-intensity large-scale freezing disaster weather occurred in 2008,which resulted in many power transmission towers collapse and break.The transmission tower is one of the basic supporting structures of the transmission line.Its reliability will have a direct impact on the reliability of the line and the whole network.Therefore,it is very important to study the reliability assessment of power grids considering the reliability of towers under different disaster conditions.Firstly,taking the actual climate data of a certain place in Zhejiang Province as reference,setting the different climatic conditions,studying the load effect,load effect ratio,load calculation,the function parameters of the tower,the basic random variables statistical parameters,and so on.Based on the JC method and narrow bound method,the reliability model of towers is established,and the reliability and failure probability of the tower system under different climatic conditions are calculated.The results indicate that the model can accurately evaluate the reliability and failure probability of the tower system.Then aiming at the contradiction between the precision and the calculation time of the Monte Carlo simulation method and in order to improve the sampling efficiency of the sampling method of reliability assessment of power system,the state space partitioning method,the system state rapid sequencing technique,the important sampling method and the Latin hypercube Sampling method are studied and an efficient improved SSP power grid reliability evaluation model based on hybrid sampling strategy is proposed.By using the model,the state space of the system to be evaluated is partitioned to obtain two subspaces,SF and SM.The analysis was carried out by analytical method and important-Latin hypercube sampling method respectively.The results indicate that the proposed model is an efficient and accurate evaluation model.Finally,set up the area to be assessed by different climatic conditions and the degree of impact,combined with the above model,calculate the failure probability of tower system.To make appropriate simplification,assuming that the line is composed of several tower systems composed of series system,and thus calculate the line failure rate.Improved SSP Reliability Evaluation Model Based on Hybrid Sampling Strategy is used to evaluate the reliability of the system.The results indicate that the method can quickly and accurately evaluate the reliability of the power grid affected by different climatic conditions.