Research On The Feeder Protection Unit Suitable For Traction Substation Automation Systems

The traction substation automation is the fundamental to guarantee the safe and stable operation of the electrical railway. In China, the technology of traction substation automation can't meet the requirement of the development of the electrical railway. Therefore, it is necessary to develop the new-generation product based on the previous operation and product developing experiences. Of which, the traction feeder of the electrical railway can be considered as the long and heavy-load transmission. The protection of such feeder obtains features different from the feeder protection of power systems although both feeders are at 35kV level. Therefore, the research on the microprocessor based protection and measuring-controlling unit using the state-of-the-art microprocessor technology becomes the main work of this dissertation. Firstly, the characteristic of traction load is introduced. The function configuration and protection set of traction network relay protection is achieved, based on the analysis of traction network relay protection principles. The adaptive distance protection is chosen as the main protection. The hardware design of traction network relay protection device is introduced. For the sake of higher reliable performance, more friendly interface and implement of TCP/IP protocol based on Ethernet, double CPU hardware structure is designed. One of the CPU module kernel implemented with 32-bit floating-point processor TMS320C32 DSP (Digital Signal Processor) focuses on protection calculation and control. The other one uses ARM (Advanced Reduced Instruction Set Computer Machine) S3C44B0X to handle rested tasks such as communication and human-machine interface. With the use of 16-bit parallel output analog-to-digital converter AD676, conversion time is greatly cut yet conversion precision get improved. The peripheral circuit is simplified by CPLD (Complex Programmable Logic Device) EPM7192S, which expands I/O and controls the peripheral electronic components. Embedded operating system used in the device is a bright spot. To programme more stable and maintainable software for protective relay, this dissertation attempts to use RTOS (Real-Time Operating System). A highly portable, ROMable, very scalable, preemptive real-time, multitasking kernel uC/OS-II is ported to TMS320C32 DSP. And the embedded Linux operating system uClinux applied on ARM S3C44B0X makes it easy to implement TCP/IP protocol based on Ethernet. As to the application protocol, this device chooses the ASDU (Application Service Data Unit) of IEC 60870-5-103 together with TCP protocol as the protocol used in traction substation, chooses IEC 60870-5-104 protocol as the protocol used between traction substation and remote control center.