Relay Protection Reliability Evaluation For Condition-based Maintenance

As the first line of defense of power system,relay protection has its own reliable operation as an important guarantee for electrical power system security and stability.With the large-scale construction of EHV and further realization of the national interconnection,the structure and operation mode of the power grid have undergone major changes,and have also proposed higher requirements for the reliability of relay protection.The maintenance of the relay protection system can effectively improve the reliability of the relay protection system.Meanwhile,the formulation of the condition maintenance strategy needs to be guided by the current reliability of the relay protection system.Therefore,the reliability evaluation of the relay protection system is of great significance to strengthen the reliability and operation level of the relay protection system and to ensure the safe operation of the power grid based on the assessment results of the reliability of each dimension.It is a common and universal issue to the electrical power system.This thesis evaluates the reliability of relay protection from three aspects:the reliability of hardware and software of relay itself,the reliability of relay protection of different protection schemes and the real-time reliability of relay protection in actual working environment.The main contents are as follows:First of all,based on the relay protection system with complete protection function,the reliability basic data of each function module of the protection system is focused on the protection of the hardware and software reliability of the system.Based on the failure characteristics of relay protection,Weibull distribution is the model of life distribution of relay protection.Considering the comprehensiveness,representativeness and testability,the evaluation index system of relay protection reliability is selected.Considering the hardware system and software system of the relay protection body,circuit breaker and transformers,the dynamic fault tree model of protection system are established;the conversion method of dynamic fault tree and fault matrix is established;and finally the quantitative evaluation of the dynamic reliability of the protection system is carried out based on Monte Carlo simulation.Secondly,taking the relay protection system with complete protection as the object and the relay protection system with different protection configuration as the focus,the significance of relay protection reliability evaluation with different protection configuration modes is analyzed.The research of power system components,power lines,bus line,transformers and other different power equipment specific protection configuration scheme;Based on Markov state-space method,different protection configuration scheme relay protection reliability model is established and different protection configuration scheme reliable model to apply to the actual example Conduct reliability analysis is also founded,comparing the reliability indicators and related factors and weaknesses of different protection configuration schemes;Thirdly,aiming at the relay protection system with complete protection function,the author focuses on the actual operation environment of relay protection such as temperature and humidity,and establishes the evaluation factor set which influences the reliability of relay protection.The multi-level fuzzy theory evaluation model,Based on membership function and analytic hierarchy process,the status of relay protection is evaluated.The evaluation results reflect the influence of the current operating environment of relay protection on its reliability.Finally,based on the evaluation of the reliability of the above three dimensions,a relay protection reliability evaluation software is developed,and a comprehensive maintenance strategy is formulated based on the evaluation results of the reliability of the above three dimensions.