Protection System And New Dynamic Simulation Experiment Technology Of Huge Hydro Generator

With the fast development of power system, many hydropower projects equipped with huge hydro-generator have been put into operation and some starts their construction. Among them, three gorges power plant is the typical representation. Huge hydro-generator will gradually become the main power of hydro power in our country. Its safety running or not will directly affect the safety of power grid. And because of the complexity of huge hydro-generator structure, the requirement for relaying protection system's performance must be higher, so the research development of huge hydro-generator protection system with good performance is the most important task for the protection technicians in our country. The research work centering on the protection system research development and some key technical issues, such as: the construction of dynamic physical model system, the research and improvement of protection principle and technique will be done in the dissertation.The dissertation dissertate the protection system scheme of the huge hydro-generator. It includes the overall design scheme, protection principle scheme, device hardware scheme and software design scheme. Protection system scheme considered the huge hydro-generator's characters such as design, structure, connection, operation and so on, and used the design and operation experience of the current related protection system for reference. By the reasonable panel configuration, the perfect protection configuration, the combination of new technology and mature theory, on the basis of hardware platform with high performance processor and modular software structure, protection system can meet the demands of huge hydro-generator operation requirement, at the same time, has a more strong universality.The dynamic physical model system of huge hydro-generator is introduced in the dissertation. The model system is the only one experiment system used as structure simulation for huge hydro-generator in our country until now. Its main components and the subsystem's structure, parameters and performance are same with prototype generators or basically consistent. Some experiments which are done in the model system are also introduced. The experiment results show that the dynamic physical model system provides a good physical experiment research platform of further research on the operation condition analysis, fault study, parameter setting, related protection performance verification and improvement for huge hydro-generators.As one of the most important generator main protection, unit transverse differential current protection could protect stator winding inter-trun short circuit fault and branch cut fault effectively. The unit transverse differential unbalance current (UTDUC) and unit transverse differential fault current (UTDFC) are the two components of unit transverse differential current, and the value and change law of this two current on various operating conditions are very important to the setting choice and criterion improvement of unit transverse differential protection. The cause and main influence factors of huge hydro-generator UTDUC are analyzed in the dissertation, then, the UTDUC on various operating conditions are researched by dynamic simulation experiment, digital simulation experiment and prototype experiment. Furthermore, the UTDFC change law on various internal fault conditions is also discussed. Based on the above research results, the new schemes of protection algorithms, criterions and setting methods are proposed. The experiment results indicate that the new scheme improves protection sensitivity remarkably on the basis of good reliabilities as compared with original protection scheme, and the reliability, rapidity, sensibility and selectivity of protection are unified well by the new scheme.In current field circuit ground fault protections, Ping-Pang type protection and low frequency voltage injection type protection are widely used for their merits, but there are some problems in protection application. The Ping-Pang type protection's performance will be influenced by the improper choice of component parameter in switch circuit and the change of ground resistance value, moreover, the protections cannot detect field circuit ground fault while generator is in free-running operation or shut down. The injection voltage sources of low frequency voltage injection type protection are special low frequency voltage source, the sources have the disadvantage of large volume and high price, moreover, their output voltage frequency could not be regulated conveniently according to the practical operation requirement. Aiming at these problems, some research work is done in the dissertation. Some proposal about the component parameter choice and structure of Ping-Pang type protection switching circuit are put forward, and an improvement scheme about the protection implementation is proposed. Combining the merits of Ping-Pang type protection and low frequency voltage injection type protection, a new protection: switching type protection with injection voltage is introduced, the operating condition of new protection in three gorges power plant indicates that the protection runs reliably, its performance is very good, so the protection's engineering application have a good prospect.In order to fully exert generator' efficiency on the basis of ensuring generator's safe operation, various inverse-time characteristic protections of huge hydro-generator are researched in the dissertation. The research includes the performance comparison for various protection operating characteristic curves and algorithms, and the setting calculation and some related application problems of protection are also analyzed. Based on the research results, the optimum inverse-time characteristic protection scheme which is suitable for huge hydro-generator is formed.In the dissertation, the comprehensive dynamic simulation experiment and stator winding ground fault protection dynamic simulation experiment of huge hydro-generator protection system are also introduced. The sensitivity, reliability and operation stability of protection system are proved by the experiments.At the end of this dissertation, the research results are summarized and the further investigative directions are pointed out.