Research On Time-varying Fault Probability Model Andapplication Of Power Equipment Based On The Change Of Operating Conditions

With the development of the UHV grid, AC/DC hybrid and new energy, the complexityof the interconnected power grid is more and more high, the pressure of power grid operationcontrol is increasing, so the power dispatching operation is faced significant challenges. Thepower development trajectory based on risk degree is a kind of power system developmenttrend indicator, which is combined with the accident probability and its consequences in realtime and future short time scales; it has the guiding role for power personnel to analysis theblackout risk. The time-varying fault probability of power equipment is the basis data of riskdegree calculation, so the equipment fault probability model is an important part of thepower system development trajectory. The power equipment time-varying fault probabilitymodel based on the changes of the equipment operation conditions and its applications arestudied in this paper.Equipment fault probability is usually calculated by the reliability parameters, such asfailure rate, so the equipment failure rate model is improved in this paper. Equipment failurerate is combined with the aging failure rate and the occasional failure rate, aging failure ratemodel is established by using the multi-state Markov process, which the method of assessingthe equipment status is improved by using the equipment monitoring information. Theoccasional failure rate is established by using the weighted average method through theIEEE three states weather model.Equipment fault probability model is improved, the equipment failure probability modelis divided into the device itself fault probability model and device outage developmentprotection action model. The device itself fault probability model is established by using theMarkov process considering the device is irreparable, and the device outage developmentprotection action model is established by using linear fitting method, both of them make upthe equipment time-varying fault probability model. The model can predict the equipmentfault probability of the future period of time when the device status and the future operationcondition are known.Considering the uncertainty of the external environment and the power systemoperation condition and historical statistical data is not perfect, the method of using thesubjective bayes to establish equipment fault probability model is proposed in this paper.Using fault tree analysis method to classify equipment fault firstly, then fuzzy expert systemis used to establish the credibility of equipment fault considering the different operatingconditions, finally using calculation formula of subjective bayes method to get the fault probability of equipment under operation condition. This method not only considers theuncertainty of operation condition information, but also solves the influence of theincomplete statistics to fault model.The application of equipment time-varying fault probability model in the power systemdevelopment trajectory based on the risk degree is discussed in this paper. From thealgorithm process of the power grid trajectory, time-varying failure probability is one of thebasic data about the power grid trajectory, so the equipment time-varying failure probabilitymodel is reasonable directly affects the power system trajectory is reasonable.