Reliability Analysis Of Station Power System Based On Fault Tree And Markov Mode

With the constant development of power industry The Structure of power grid is more complex and compact.Under the background of building f Strong and Smart Grid,the requirements of power system's reliability should meet higher standard.Station undertakes important functions such as power transformation connection.With the continuous promotion of unattended station.How to maintain the safe and reliable operation of equipment in substation stations is particularly important.Station power s system is responsible for all kinds of AC,DC equipment.The uninterruptible power supply is responsible for the communication,monitoring system,The AC power loss will lead to the station to be isolated.DC power supply can provide DC power for the relay protection,circuit breaker and other automation equipment.Equipment refusal to move and incorrect operation cause large-scale blackouts.The safety and reliability of the power system for the station is the cornerstone for stable operation of the equipment in the station.With the advancement of substation intelligence and digitization,the reliability level of the station power system should meet higher requirements.In the past,the analysis of the station power system analyzed the AC uninterruptible power supply or the DC operation power supply separately,and there were certain deficiencies in the previous maintenance methods and maintenance contents.Therefore,in the new environmental context,the reliability and maintenance of the station power system maintenance methods need to be reassessed.Based on the fault tree theory and Markov space state method,the paper analyzes the reliability-related indicators and the typical reliability model.The fault tree analysis method is used to model the uninterruptible power supply part and the direct-current power supply part of the station power system.The fault tree model of single UPS system,double UPS series system,dual UPS parallel system,and fault tree model of double-charged single-storage DC system and triple-charge dual-accumulation DC system,quantified the weakness of the system through probability importance.Combining with the level of the failure rate of utility power,established the reliability change curve of the system in the first ten years of operation under different levels of power failure,and conducted a comparative analysis.The results show that with the increase of the level of mains failure rate,the importance of the battery increases significantly,which is the weak link of the system,and the inverter is also the weak link of the communication part.Aiming at the weak links of the system,a state maintenance scheme based on internal resistance monitoring was proposed.Taking a typical 110kV substation as an example,a multi-state Markov model of the station power system was established by the Markov state space method.In comparison with the improved scheme,the reliability transition curve of the system under considering the overhaul mode is obtained by solving the state transition matrix equation.The results show that the state-based maintenance scheme based on battery internal resistance monitoring can detect system failures early and maintain the system reliability at a higher level,which is superior to the traditional scheme of improving only the AC system.It provides a certain reference value for the operation and maintenance of the station power system.