Intelligent Residual Current Opreating Protective Relay Base On MCU Of P87LPC767

An intelligent Residual Current Operating Protective Relay is designed in this article based on the analysis of domestic and foreign Residual Current Operating Protective Relay present product performance, which is controlled by P87LPC767 monolithic integrated circuit. The instrument managing the resources of the P87LPC767 monolithic integrated circuit has lots of functions such as data display, storage, inquiry and manual setting steps, automatic fluctuation, action phase instruction and so on. The thesis systematically proposed the whole design and the implement method.The technique of measuring residual current phase and its root-mean-square is discussed in detail in the thesis. This paper also has analyzed the digital sampling technique and has introduced three main digital sampling methods, which are synchronous, non-synchronous and quasi-synchronous sampling method. According to the function requirements of the Residual Current Operating Protective Relay, I choose non-synchronous sampling method to reduce product costs and to enhance performance and price ratio; at same time I select software to control measuring accuracy by the means of adjusting the differences. To the signal measure, I make the best use of external interrupt resources, timer and so on provided by P87LPC767 monolithic integrated circuit, meanwhile sampling and measure half period wave and calculate root-mean-square. Thus the contradiction between data sampling operation and protector action has been solved well.The debugging is analyzed as the emphasis in the article, including the realization of criterion, and the design of multi-time-lapse program, and analysis on error and restrictor on it, and the design on electromagnetic compatibility and so on. All these problems are settled in the paper, which gives two criterions on residual current protection and designs of hardware and software to cut down the infection of error. In the software programming aspect, the datum signal the trigger pip is used for the monolithic integrated circuit interrupt, so that multi-time-lapse procedures can be designed to realize a new to write time-lapse and delay procedures without timer. The problem of electromagnetic compatibility is settled effectively by a program designed to monitor the interference signal in high frequency.