Research And Design Of Microcomputer-Based Main Protection System For Transformer

Power transformers are most important equipment in power systems, with the development of the power system, especially with the evolution of the modern material and new crafts, and the enlarging of the capability in power transformers, they have a great influence on the secure and reliable operation of power system, and therefore, the requirement for transformers protection becomes much stricter. And then their reliability is of crucial importance for the energy system operation. The protection relay system is an automation system that it can reflect the fault and the deviant state of electric power system and drive the breaker's action or send out the fault message. The role of protection relay system is to cut off the fault module in an automatic, rapid and selective manner and avoid destroying the system. The exploration and application of microprocessor protector has a great active significance to ensure the safety operation of electric network.This paper mainly discussed the principle of 110KV-transformer microcomputer based main protection. A novel simple method for calculating the Discrete Fourier Transform (DFT) spectra applied in power system microprocessor protection and a scheme and realization of microprocessor-based protection system was put forward. This instrument has the features of rapid response speed and high sensitivity and has been passed through quality certification of state power correlation department. The preliminary running effect of this device shows that it satisfies the functions and indexes of system completely.The chapter arrangement of this paper is as follows: Chapter 1 simply describes the developing history, the actuality, trend of microcomputer-based relay protection, and then a scheme of microprocessor-based protection system is introduced, finally it describes the content of this research; chapter 2 analyzes and calculates the algorithm of microcomputer protection, and puts forward a simplified arithmetic based upon DFT in microprocessor-based protection; chapter 3 discusses the configuring and working principle of transformer protection; chapter 4 designs the hardware platform's structure of protection system by adopting industrial grade chip MCF5282 produced by Freescale and based on RISC technology as CPU of the device; chapter 5 proposes the software design of computer-based main protection relay of 110kv transformer; chapter 6 makes a conclusion of the paper and brings forward the continued research work in future.