| The accurate and effective equipment maintenance strategy is the cornerstone of stable,efficient and healthy operation of all kinds of electrical equipment,and is the guarantee of improving the reliability of power supply and the safety,stability and economy of the whole power system.The modern power grid is constantly developing towards being intelligent and environmental friendly.As a result,the effective operation of each equipment component is disturbed by various factors,which brings new challenges to the maintenance,early warning and safe production of power grid equipment.The traditional post-fault maintenance and time based maintecance(TBM)strategy is no longer applicable.Condition based maintenance(CBM)strategy emerges as the times require,and becomes an important means and technical support for improving the optimal management of power grid equipment.In view of the main problems existing in the maintenance of power network equipment and the actual requirements of enterprise management,this paper systematically discusses the maintenance strategy of power network equipment in the state of operation risk.The main research contents are as follows:First,by analyzing the equipment level in the power distribution network,and determining the equipment state parameters and status evaluation standard according to the relevant guidelines,the existing evaluation points system of state parameters is improved,and the equipment running status is comprehensively analyzed and evaluated.The analytic hierarchy process(AHP)combined with expert knowledge is applied to determine the weight coefficient of each state parameter,comprehensively score the health degree of the equipment,and so as to understand the operation status of the equipment,and provide the basis for the subsequent risk assessment and state maintenance decision.Taking 10 kV oil-immersed transformer and 10 kV overhead line of distribution network as an example,the state parameters stratification model of transformer and overhead line is established,and the weight coefficient of each state parameter is determined by its characteristic vector.Secondly,under the background of real-time state feature monitoring,and considering the relation between the reliability of power network operation and the failure probability of electrical equipment,this paper obtains the health information of the equipment synthetically,judges the health status of the equipment components,and then studies the distribution rule of the failure rate of electrical equipment.In addition,the close relationship between equipment failure rate and climate factors is investigated in this paper from the angle of externalenvironment change,and based on multi-state Markov process,an external accidental failure rate calculation model of transformer and overhead line considering weather factors is established,which can synthetically calculate failure rate under different conditions of electrical equipment,and lay a foundation for the next operation risk calculation and condition based maintenance strategy of equipment.Finally,based on the results of the state evaluation and failure rate calculation,a condition based maintenance decision model based on grid operation risk is established in the study.This paper first constructs the risk assessment model of power equipment,and introduces the composition and calculation method of the comprehensive risk value.The impact of equipment status on power supply enterprises is considered from two aspects: the risk of loss of equipment itself and the risk of loss of power network operation.Then,the risk values are graded according to the Technical Guidelines for Risk Assessment and Operation and Maintenance of Power Distribution Equipment,and the corresponding risk levels are assigned with maintenance strategies.In the end,we demonstrate the usage of the method with practical cases,and give the corresponding maintenance strategy,to verify the applicability of the theory proposed in this paper. |
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