| Substation is the hub of regional power system network,which plays an important role in converting voltage grade and distributing power load.Compared with the mature conventional substation system,the design of the intelligent substation primary system and automation system is still in the practice stage.Evaluating the reliability of the intelligent substation automation system,and then evaluating the reliability of the entire intelligent substation primary system and secondary system,so as to guide the design of the substation primary electrical system and automation system.This is of great significance for improving the stability of the entire substation and regional power system.The traditional reliability analysis of substation automation system has many shortcomings in considering the correlation within the automation system.It often ignores the common devices and data communication between different subsystems or different bays,or when considering the functions of a system,it includes the irrelevant modules in the devices participating in the functions into the calculation.In addition,the traditional reliability analysis of substation automation system is mostly based on the binary division of all components intact or all components faults,failing to express the multi-level state of function degradation of substation automation system.Aiming at the correlation problems existing in the reliability analysis of substation automation system,this thesis first proposes a reliability analysis and model method based on FMEA(Failure Mode and Effects Analysis)for each equipment of substation automation system,and analyzes the distributed functions of the substation automation system in which each equipment is involved,as well as the failure mode of distributed functions caused by the failure of each functional module within the equipment.Then the reliability model based on node link network of two design structures of substation automation system are established.According to the similarity and relative independence of each bay model,the automatic system is divided into the bay model of each voltage level and each kind of bay,and the model of the communication of the station control level.According to the previous analysis of the distributed functions involved in each device and bay function module,FMEA is adopted to analyze the distributed functions involved in all functional modules and links in the bay model.Combined with the minimum downlink method of fault tree,the availability of distributed functions and sub-functions is calculated.On the basis of considering the correlation,the communication function of the station control level is integrated with the distributed function of each bay to obtain the fault tree of the whole station automation system,and then the distributed function and the overall availability of the whole station automation system are calculated.The comparison between the overall availability of the substation automation system with two structures and the comparison between the availability of each distributed function shows that the reliability analysis method proposed in this thesis is more accurate than the traditional analysis method in judging the actual reliability of the automation system structure.Aiming at the function degradation problem existing in the reliability analysis of substation automation system,this thesis proposing a state partitioning method based on functional degradation scenario analysis.By analyzing the different emphases of each subsystem in the actual work,it shows that the main part of the demotion state division can only be each subsystem but not the whole substation automation system.Based on the analysis of the different bay or different sub-function failure in each subsystem,the degree of power failure and failure scope enlargement of the primary system is different,and the degree of adverse impact on the actual work is different,the multi-level function degradation state of each subsystem is divided reasonably.Based on the improved FMEA analysis method,the state of each subsystem caused by different bay of each subsystem or the combination of different sub-functional states is analyzed,and the reliability model of subsystem function degradation based on the improved FMEA is presented.By giving the calculation method considering de-correlation,the multi-level reliability of each substation automation subsystem is obtained.The reliability calculation results of substation automation system with two structures considering functional degradation are compared and analyzed,and the results are compared with those of traditional reliability analysis methods.The comparison results show that the reliability analysis method of substation automation system considering functional degradation proposed in this paper can consider the reliability of the system from many aspects and multiple levels,and effectively solve the limitations and shortcomings of the traditional reliability analysis method. |
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