| At present,the core components that make up various types of relay protection devices are almost entirely rely on imports from Europe and America,which poses huge safety risks.Protective relaying is the first line of defending for the security of power network operation,and it is also the core secondary equipment of power network.Its reliability is particularly essential to ensure the safety running of power network.Therefore,State Grid Corporation has formulated an important development strategy for "Digital State Grid".This thesis researches the reliability design of relay protective device based on localized core components.The main works are as follows:At first,the failure rate of the core components of the relay protective devices is analyzed.By comparing different reliability prediction standards and based on the features of the secondary electronics equipment of the power system,the failure rate prediction models of domestic electronic components and imported electronic components are established to predict the failure rate of domestic and foreign core components.From the perspective of core component redundancy,the influence of different redundancy methods on the reliability of core components is analyzed to provide a basis for subsequent core component alternatives.Further,a replacement scheme of core components of low voltage level relay protection device considering failure rate and economy is proposed.Specifically,based on the structures of relay protection device,the optimization models of localization alternatives for core components of relay protection with the lowest cost under the fixed failure rate requirement and the lowest failure rate under certain cost requirement are established respectively,and the genetic algorithm is applied to compute the model.Based on the failure rate and cost data of domestic core components of relay protection,the possible replacement scheme for localization of core components is analyzed.Furthermore,a replacement scheme of core components of single relay protection device considering the risk of mis-operation and mil-operation is proposed.Based on the possibility of both mis-operation and mil-operation of relay protection,the calculating method of mis-operation and mil-operation risk of relay protection is deduced by Markov model.By establishing alternative optimization model considering risk,the corresponding mis-operation and mil-operation risks are calculated,and the possible localized alternatives of core components under different failure rate requirements of relay protection are analyzed.Finally,a replacement scheme for core components of high voltage level dualized relay protection device is put forward based upon the Markov model.In view of the dual characteristics of high voltage relay protection devices,the calculating method of relay protection unavailability is deduced by using Markov model.Further,from the perspective of one-by-one replacement and cross-substitution of domestic core components,by calculating the unavailability and replacement cost of relay protection devices when different domestic core components are replaced,and the replacement sequence of the core components is determined based on this,so as to constitute the alternative to the core components of the high-voltage dual relay protection. |
