The Development Of Protection For Large Tranformer Of Three Gorges Generator-Transformer Sets

Three Gorges Generator sets have very high-capacity, its running safety and stability have an important impact on Three Gorges station and even on the whole power system. So far most of the large multi-branch generator-transformer sets have adopted foreign protection, though they have had good performances, there still existed some problems to be improved. At the same time, as start building of many hydropower stations of China, the protection's nationalization of large generator-transformer sets needs to be solved. So taking the running characteristic and application requirement of Three Gorges large generator-transformer sets, it is a study with very important theoretical and realism value to develop domestic large generator-transformer sets protection with high performances.Combining the development of generator-transformer sets protection, this paper focused on the development of transformer protection. At first, development history of transformer protection has been reviewed and then the protection's study has been analyzed and surveyed. This paper presented the key points and the major contents on the basic of previous.The design principle and required function of transformer protection have been explained and the general design has been made on the basis of Three Gorges generator-transformer sets'structure and protection's requirement in this paper. This paper introduced the hardware basic structure, the protection design and supervisor software design.Hardware design is very important in the development of transformer protection. The hardware system needs higher reliability and better resource configuration because of the integration of main protection and backup protection, and also because of the digital output's flexible configuration based on the field requirement. The hardware adopted the working model which has one supervisor and double protection unit. Protection unit adopted the TMS320C6713 DSP as CPU, which has fast calculation speed and large storage capacity, and can meet the requirement of complex protection well. Supervisor unit adopted the ARM9 processor based embedded LINUX operation system; it has abundance resources to realize friendly human-computer interaction and communication. This paper produced the basic principle of compositionality and function characteristic of hardware. Protection principle is the core and basic of protection device, and plays a crucial role to the performance of device. A multi- principle main protection scheme has been presented in this paper to develop the different protection principle advantage and improve the general performances, which based on the analysis of some typical frequently used main protection principle. This paper introduced how to combined with each other between different main protection principle, the realize theme of backup protection and the main protection algorithm adopted.The modularity and transparency of protection software based on the design principle of reliability, reusability and expansibility has been studied in this paper. The object oriented and relay modular based software design method have been adopted to raise efficiency, to make it easier to extend and to realize the implementing monitoring and data record. This paper produced the basic structure of software, the basic concept of modularity design and the realization of main software module.The Three Gorges large transformer protection relay has already passed the implement static and dynamic tests. The results show that the general performance of this device has fully meet the requirement of design. The main test content and specific result has been produced in this paper.