Methodology Study And Practices Of Optimal Maintenance For Gezhouba Hydro Power Plant

Advanced maintenance is currently the focus concern of hydro power plants. Though the condition-based maintenance system has been developed in succession in some large hydro power plant since 1990s, the expected objective hasn't been realized due to the lack in realization, technique and management.The Gezhouba project is constructed independently and is a large water conservation and hydropower project in China. Microcomputer Controlling turbine-generator sets and computer monitoring in Gezhouba Hydro Power Plant have been established via reformation and construction since the first turbine-generation was put into practice in 1981. And the plant takes the lead in passing the unattended standards. Besides, ePMS (Electric Production Management System) has been developed under the unified planning. Based on the investigation on the automation, informatization and the maintenance technique in home and abroad, the objective of researching and developing HOMIS (Optimal Maintenance Information System for Hydro power plants) is discussed, which use the independently developing experience in the plant, such as computer monitoring system, microcomputer-based governor, microcomputer-based excitation system, microcomputer protecting and so on. On one hand, HOMIS will integrate the control and management system and make full use of the existing resources of digitalization in order to realize maintenance automation. On the other hand, HOMIS will improve the informatization and automation of Gezhouba Hydro Power Plant to a higher level and make the combined operation between the plant and Three Gorges Hydro Power Plant which arrives at advanced level in the world.Considering the facts of operation and maintenance of hydro power plants in China, the optimal maintenance strategy is proposed, which comprehensively allows for the reliability and economic benefits. According to the principle of gradual and orderly progress, the guideline for the development of maintenance should be that the scheduled maintenance will be reduced, the corrective maintenance must be avoided, and the condition-based maintenance is gradually realized. Besides, the guideline focuses on the security and reliability of equipments and achieving economic and social benefits to the greatest degree. Finally, the optimal maintenance will be realized via scientifically combining different methods of maintenance.A system is composed of different equipments and sets accomplishing tasks as the goal. The structure relationship and the methods of describing and estimating the equipment status, the system behaviors and task-quality as well as the relation among them are clearly illustrated via modeling of system structure and its behavior relationship. Consequently, the tasks and the realization methods of controlling and maintenance automation are ascertained. On the basis of the model, the demands of HOMIS are clarified from the point of view of operation, maintenance, management and technique so as to enhance the pertinence of developing HOMIS and to make HOMIS acceptable for different workers in hydro power plants and join in the enterprise activities.Turbine-generator set digitization is pivotal to improve informatization and automation of power plants. The exploratory researches on digitization of turbine-generator set technical documents, expert knowledge and experience, and operating conditions, which can be used by human experts and computer experts, are carried out. And the whole idea of digitization modeling comes into being primarily. The modeling methods are presented with examples.Based on expert intelligent, the methods of analysis and diagnosis are given. The expert system via computer analysis and diagnosis, which imitates the analysis and diagnosis methods that operating and maintenance experts analyze and diagnose the health of equipments, is built on the basis of turbine-generator digitization. With respect to the performance indexes of operating condition and task accomplishment of systems, fault events and degradation events of performance can be found out via detecting condition and performance over limits or tendency analysis of condition and performance. And then, in terms of the digitization model of fault tree, the suspected equipments will be listed in decrease order of fault probability. Finally, the methods of model reference and signature analysis are employed in eliminating suspected equipments and discovering the fault equipment. In addition, the supervision, examination and intervention of experts are accepted in the whole process of analysis and diagnosis.Aiming at the trait of the high difficulty and long period of construction technique of the system of digitization of turbine-generator sets and power plants, maintenance informatization and automation, the system function and architecture is generally figured out one time, and the system is built step by step, and the benefits of system can be achieved in the construction process.The optimal maintenance information system for Gezhouba Hydro Power Plant is consisted of the digitization and analysis & diagnosis system of turbine generator sets, the wide area network platform, the remote monitoring and diagnosis, maintenance decision support expert system, training and assessing system. The topologic structure and functions of first two systems are designed.By now the digitization and analysis & diagnosis systems of three turbine generator sets and the wide area network have been set up and put into services. They played a very important role in the operation and maintenance in Gezhouba Hydro Power Plant. Markable benefits have been achieved.