Study Of Condition-based Maintenance Strategy For Electric Equipments In Power Grids

The maintenance strategy of power grid equipments plays a leading role in assuringhealthy operation of the equipment, improving power reliability and safety and security as wellas the economic efficiency. The power grid in China marches towards green power grid andstrong power grid and aims at realizing the development objectives of reliability, safety,economic efficiency, high efficiency and safe use, with consequently higher production qualityand management on electricity grid. Facing the challenge and opportunity of the developmentof power grid, manufacturing of power grid equipments has been improved on quality, theequipment performance and quality have been developed a lot, the conventional maintenanceafter fault and periodic maintenance strategy are not applicable and the condition-basedmaintenance and strategy comes out and become the key means and technical support foroptimization management of power grid equipments management. Aiming at main issues inthe maintenance of power grid equipments and actual demands of corporate management, thispaper systematically researches the maintenance strategy of power grid equipments, discussesthe involved condition evaluation, fault probability analysis, risk evaluation, maintenance,planned maintenance optimization and auxiliary decision-making and development, andproposes complete thoughts for maintenance of power grid equipments condition and somenew evaluation, evaluation and analysis algorithm applicable to power grid equipments, withmain researches as follows:1. To solve the concept of fixed right evolved into varying rights in the conventionalpower grid equipment and inconsistency core thoughts of the evaluation model, based on themulti-attribute and multi-layer analysis method, propose the model for varying rights of powergrid equipments. The model breakthroughs the restriction conditions that all conditionparameters in the conventional condition evaluation must have the same condition values andeach condition parameter of the equipment shall be divided into definite probable values toenable description of each condition parameter is more accurate. This model, to some extent,reserves the Reductionism of the conventional AHP in combination with the analysis thoughtof holism, the analysis process is easily operable and more scientific and proper. Analysis andcomputation are carried out with220kV circuit breaker and10kV overhead transmission line. Based on theoretical research, the J2EE system framework is used to develop the auxiliarydecision-making system for condition of the equipment, which has been in trial operation inthe power system.2. Based on the deviation with the EA experience formula on analyzing interrelationshipof power grid equipments condition and fault probability and the non-linearity regressionanalysis principle, with the history statistics data of power grid equipments condition and thefault probability, propose the modification method to the EA experience formula. Throughtracking and collecting the condition evaluation results and fault data of Shenzhen power grid110kV power cables and Guangzhou power grid10kV overhead transmission lines from theyear2010to2011, the SPSS statistics analysis method is applied for sample parametersestimation and compose the relationship curve on operation condition of power gridequipments and its fault probability, and the non-linearity regression relevancy ratio is used tocalibrate the modification function.3. On the basis of evaluating the equipment assets and load losses to the power grid byequipment faults, risk evaluation of power grid equipments is carried out, and maintenancestrategy is formulated based on the operation risk level of the equipment, and analysis andcomputation is carried out with Shenzhen power grid110kV power cables. Based on the totalservice life of the equipment, based on power grid equipments risk evaluation, propose theeconomic analysis model of the optimum maintenance proposal with minimum annual averagecost. The annual average cost is the annual average cost of fund losses, operation cost,investment cost and etc. from the equipment operation risks considering the time value of thefund. This model considers its own risk of the equipment and the risk caused to the power gridby the equipment fault. Maintenance of the equipment is expanded from the conventionalsingle tier to the comprehensive tier of equipment and power grid. Analysis and computationare carried out with220kV transformers of Shenzhen power grid.4. Based on actual demands of maintenance of power grid equipments, in consideration ofinitial condition of power grid equipments to be maintained arising from planned maintenance,provisional maintenance, fault maintenance and etc., propose the multi-objective andmulti-restriction decision-making and analysis model on optimization of comprehensivemaintenance schedule of power grid equipments. This model combines the health condition of the equipment, with the permutation and combination of the maintenance sector of theequipment to be maintained as the decision-making variants, with power grid operation mode,load level and operation and maintenance resources as the restriction conditions and the powergrid economic efficiency, reliability and working quantity as the joint optimization objective.The optimization process is the multi-objective different evolution algorithm based on the elitereservation strategy and objective function sequencing to acquire the full Pareto frontieroptimum solution sets to produce several optional proposals and offer the power enterprises forcomparison analysis and final decision-making. Take RBTS-BUS6as example for analysis andcomputation to verify reasonableness and effectiveness of the model. Based on theoreticalresearch, propose the physical structure, logic structure and function module design thoughtsfor auxiliary decision-making system of the comprehensive power grid equipment maintenanceschedule and adopt the Java corporate application platform is used for systematic development.The system automatically produces the optimized decision-making proposal by quantifiedanalysis, evaluation and comparison for maintenance of power grid equipments, and hasfunctions of automatic relevancy reminding, working quantity balance analysis, auxiliarymaintenance schedule updating and maintenance equipments analysis and evaluation and otherfunctions and has been in trial operation in the power system.