Assessment On Economic Life Of Intelligent Station Relay Protection Based On Life Cycle Management

At present,the basis for the development of the overhaul protection plan for relay protection devices in the power industry are mostly based on the analysis of the reliability of the device,the over-maintenance,or early decommissioning,which results in the loss of company assets.Therefore,when considering the reliability of a protective device,it is necessary to take economical considerations into account.taking the whole life cycle management as a theoretical basis,comprehensively evaluate the cost of the operation,the economic life of the protective device,and finally determine the best time for retiring.It also can make electric power companies improve the management of secondary equipment such as protection devices.Firstly,analyzing the method of solving the real-time state probability of the protection device and fitting the failure rate curve.Starting from the concept of reliability of relay protection equipment and its main evaluation indicators,explain the definition of the method of reliability,failure rate,repair rate,and average time between failures.After that,a method to obtain the real-time state probability based on the Markov process is proposed,and then obtain the real-time failure rate of the protection device.The bathtub curve commonly used in engineering is used to describe the life of the device intuitively,and the failure rate prediction curve is accurately fitted through the Weibull distribution function.The example analysis shows that the classification of the protection status can be obtained based on the information of the actual intelligent station message,which helps to calculate the probability of the real-time status and predict the failure rate curve.Then,we study on the risk consequences of protective devices and calculate the risk assessment.According to the general definition of risk assessment,the risk of a protective device is defined as the product of the probability of failure of the device and the damage it may cause.By correlating the primary power device corresponding to the protection device,it can ensure the load loss of the primary power device caused by the protection failure which is regarded as the risk consequence,and a multi-state failure risk assessment model is established.The example verification shows that this model can effectively evaluate the fault risk of the protection device in the power grid system and has guiding significance for the decision-making.Finally,the economic life of the protective device was evaluated.Based on the real-time failure rate and failure risk assessment results of the device,we analyze the protection device economic elements,and also calculate the annual operation and maintenance costs,the annual accident risk cost and the annual maintenance cost.Considering the reliability and economy,we propose a life-cycle assessment model for protection devices based on life-cycle management theory.We can calculate the current value of the device based on the depreciation method for the sum of the years,and the lowest cost equivalent of the life-year is used as the criterion to obtain the best economical retirement time.The actual power grid calculation example shows that this model can accurately obtain the best decommissioning time of the economical protection device and help improve the management level of the secondary equipment for the power company.