Research Of Monitoring And Managing Subsystem For Large Scale Three-Winding Autotransformer Protection

Autotransformer is extensively used as the increase of the demand for extra high voltage & large scale transformer in power system just for the following merits: saving in material, low cost of manufacture, low loss, high operational efficiency, low no-load current, low exciting power, small volume, improve the stability of the net, etc. As the operation reliability and performance of human-machine interface of autotransformer do not work well in the field, therefore it is of urgent and practical significance to research reliable & perfect protections and intelligent monitoring & managing system.First of all, this paper analysis the development of autotransformer protection device. Based on the typical connection of large-scale three-winding autotransformer, reliable protection configurations are proposed. As the monitoring & managing system is the bridge of human-machine interface, this paper analysis the hardware demands & software function demands, based on witch hardware schemes & software function schemes are proposed.The monitoring & managing system develops program with the hardware platform of ARM processor, with the development environment of embedded Linux and with the development tool of Qt/Embedded. Based on the discussion of embedded operation system and its related technology, this paper describes the function of file system and its making process in detail after witch realization process of menu function and the key implementation technology are introduced.Inner communication in protection device is the foundation of the monitoring & managing system. After introducing the communication principle of inner CAN bus, this paper proposes taking Modbus protocol as the inner communication protocol which consumes little resource and takes reliable data check.With the development of integrated substation automation, digital substation set a still higher demand to the monitoring & managing system which is to realize protection data share based on network topology in the substation. After considering the field adaptability and communication speed, this paper proposes a communication mode which takes Ethernet as the communication channel, IEC 60870-5-103 as the communication protocol to realize the communication between protection device and integrated substation automation. This paper specifies several communication processes to make the process of communication clear.Fault-tolerant processing is the other important consideration during the software design. Based on the detailed analysis of possible situation during the process of operation for the autotransformer protection device, this paper proposed according solutions which has been proved to be reliable.The autotransformer protection device has verified by virtual data test. The result shows that the monitoring & managing system has friendly interface, convince operation and good fault-tolerant mechanism. Its also realizes real-time multitask and standard communication. Abundant hardware interface and modular design method for software enhance the function expansibility and field adaptability of the system.Finally the author summaries the work, and gives outlook of this project.