Study On Proactive Maintenance Strategy For High-speed Railway Traction Power Supply System Based On Health Status

In pace with the rapid and tremendous construction progress of high-speed railway(HSR)in China in recent years,as well as a result of the Silk Road Economic Belt Initiative,huge miles of HSR home and abroad are facing a comprehensive operation and maintenance period in the next few years.The traction power supply system(TPSS)is the sole power source of HSR.It is very crucial to ensure the healthy operation and efficient maintenance of TPSS.As a result of mileage accumulation,service time increase and performance deterioration of power equipment,potential safety hazard of TPSS will be exposed gradually,and the pressure of maintenance service will shoot up.However,the existing maintenance theory and technology for TPSS are severely lagging behind for the style of “reactivity” in many ways.For example,the operation state judgment of equipment and system is inaccurate or incomplete,judgment and treatment method of failure is imperfect,and the maintenance mode is quite fall behind.Therefore,it is urgent to develop a “proactive” theory and technology of maintenance for HSR TPSS.The proactive maintenance strategy can help to improve service ability and efficiency of equipment and system,while save operation and maintenance cost and reduce workload and work pressure of the maintenance personnel.As a result,proactive maintenance strategy is able to ensure a smooth transition of HSR to the comprehensive operation and maintenance period.This paper first analyzes the characteristics of HSR TPSS in its operation and maintenance activities,including the characteristics of multi time and space scales,dynamics and stochastics.New concept of proactive maintenance for TPSS is presented with the following points: Proactive maintenance focuses on the “whole service life cycle”;Proactive maintenance is related to the issue of big data;The decision process of proactive maintenance is multiattribute;The implementation of proactive maintenance is adapted to multistate;The proactive maintenance strategies are customized according to various actual field situation.On this basis,theoretical research contents and technological implementation approaches of the proactive maintenance is proposed.As a result,a theoretical framework of proactive maintenance for HSR TPSS is formed.The core and basis of proactive maintenance is monitoring and acquiring the health status of TPSS equipment and system comprehensively and accurately.Therefore,a health assessment method for TPSS equipment and system is presented in this paper.A layered analysis model is established through the analytical hierarchy process(AHP).The fuzzy statistics method is proposed and concept of fuzzy membership degree is introduced to eliminate the influence of the randomness of cognition.This method unifies those data which have multi time and space scales into one index,i.e.,health value,to describe the health status of each equipment,each subsystem and the whole TPSS system.Results of analysis on practical example show that the health status of the TPSS equipment and system can be assessed comprehensively,accurately,intuitionally and quantificationally by the presented method.With regard to the proactive maintenance strategy for TPSS equipment,equipment served in TPSS suffers from both progressive degradation and random shocks.The failures of TPSS equipment are caused by both soft failures and hard failures.In this paper,performance deterioration and failure model are described by stochastic process.The reliability indices are obtained by considering competing failure mode of soft failure and hard failure.A proactive maintenance strategy combining monitoring,inspecting and repairing is proposed based on complete maintenance assumption.Index of reliability cost rate associated reliability and maintenance cost is defined to evaluate the maintenance strategy performance.The decision and optimization method are applied to achieve the best performance of the proactive maintenance strategy.The analysis results of gas insulated switchgear(GIS)in the case study show that the inspection period and the shock threshold,as two mainte-nance decision parameters,can be optimized to achieve both high reliability and low maintenance cost.In order to describe performance deterioration and failure process of TPSS equipment more precisely,the proactive maintenance strategy should be developed more practically.In this paper,three major issues related to the actual field maintenance operations of TPSS equipment are addressed: s-dependent degradation and shock process;both spatial and temporal failure thresholds of shocks;incomplete maintenance.The coupling model with spatial and temporal thresholds is presented.In this model,extreme shock model and ?-shock model are introduced to describe spatial threshold and temporal threshold respectively,and acceleration effects of load shock on degradation are also described.The reliability indices are obtained based on characteristic function.Furthermore,the index of availability which combines both reliability and maintainability is derived under the incomplete maintenance consideration.Based on the balance of availability and maintenance cost,the maintenance strategy for TPSS equipment is developed.The analysis results in the case study show that the proposed model and maintenance strategy in this paper are not only more suitable,but also have been further improved for the actual field situation.With respect to the proactive maintenance strategy for the whole TPSS system,a maintenance mode decision method is presented in this paper.The existing and future maintenance modes are summarized with their merit and demerit to establish the maintenance modes set.Various properties showed in the service and maintenance process are analyzed to establish the influence factors set.The Analytic Network Process(ANP)is introduced and an ANP decision model is proposed to figure out synthesize weight and to order the priorities of several maintenance modes.Results of practical example show that the proposed model can describe the decision issue with intricate structure accurately and deeply.The priorities of several maintenance modes can be ordered by allocating the weight reasonably.In the proactive maintenance strategy for both TPSS equipment and system,sensitivity analysis is an effective way to investigate the influence of model parameters or weight allocation on decision and optimization results.By sensitivity analysis,one can flexibly adjust the proactive maintenance strategy to adapt various TPSS distributed in different regions and different period.It ensures the customizability of proactive maintenance strategies to various actual field situation.The implementation of proactive maintenance strategy can maintain the excellent health status of TPSS equipment and system during their whole service life cycle.It utilizes maintenance with low cost and high efficiency to keep the best service performance of equipment and system.It ensures the permanent and high quality electric energy supply for HSR by TPSS.By proactive maintenance,the safety,reliability and economic operation of huge miles of home and abroad HSR are able to be ensured.