Study On The Condition Based Maintenance Decision-making For Transmission And Transformation Equipments

Equipment maintenance is an important part of production management. As the rapid development of power grid, the number of power transmission and transformation equipment is increasing dramatically, and the traditional maintenance system has not met the demand of power grid, which is Time Based Maintenance (TBM) associated with Corrective Maintenance (CM). Condition Based Maintenance (CBM) is well-directed and effective, as well as can raise equipment's operation level, extend equipment's life and reduce maintenance cost.There are three parts of CBM:state information collection, health state assessment and maintenance decision-making. State information collection is the premise of CBM, while health state assessment is the foundation of CBM and maintenance decision-making is the core of CBM. Recently, health state assessment can be implemented according to related guide rules, while there isn't an effective maintenance decision-making model. So this paper targets at maintenance decision-making, whose main jobs are researching on reliability based on health state, optimal maintenance time estimation and optimal maintenance mode selection.On the basis of health state assessment, a reliability model based on equipments'health state is put forward. The key part of applying the model is to calculate the two parameters of the model. After analyzing the shortcomings of the inversion method, a new parameter calculation method based on life cycle states is proposed. By means of this method, we can build the same kind equipments', a single equipment's or an even more accurate life stage's state reliability models. This method needs fewer samples, considers life cycle states, and reflects maintenance's impacts.The maintenance time should extend or shorten according to equipment's health state. First, estimate the average residual life at current state, which is the deadline. Then according to the synchronization demand, an optimum maintenance time calculating model is proposed, which is based on the joint maintenance of primary equipments with their relays. According to analyzing joint maintenance, a markov space model of the system with single protection is build, and at last the optimal maintenance time based on reliability and economic analysis is calculated.On the aspect of maintenance mode selection, this paper proposes a maintenance mode selection model based on effectiveness and cost analysis using CBM information. It defines effectiveness composed of state health indictor, reliability and availability, gives each factor's formula, and analyzes the impacts of different maintenance modes. Then, it gives maintenance cost's components with their formulas. At last, it educes a maintenance mode selection model aimed at most effectiveness per unit cost.