Research And Development Of A New Experimental Device For Digital Relaying Protection

This paper analyzes the development of the microcomputer protection and the actuality of power system relay protection teaching in college. Based on the demand of the experiments in college, a full multifunctional protection device for experiments is studied. This instrument can basically satisfy all the theories, which are mentioned in the relay protection textbook, so the students can carry out all kinds of experiments on it. Furthermore, the 16-bit advanced Flash type MCU produced by Motorola brings high performance for this instrument. And the circuits surrounded are multifunctional, including 16 channels for analog input, 16 channels for switching input, 8 channels for switching output, and the RS-232 and USB communicating interfaces. In order to get high precision in the analog-to-digital converting, two 12-bit, bipolar-input, multiplexed-input successive-approximation analog-to-digital converters are used in the instrument. In addition, a PLL ( phase-locked-loop ) circuit is used, in order to use adaptive sampling technologic in analog-to-digital converting. So the sampling frequency would make adaptive adjusting if the frequency of the power system changes any. This can keep the high precision in serious cases. Otherwise, this instrument contains enough test points for experiments, a JTAG interface for convenience debugging, and a flexible structure for easy disassembly. With a configuration software in PC and friendly interface for browsing and setting, It is easy to accomplish all the experiments and do a comparison among them.