Relay Protection Systematic Communication Converter On The Basis Of RS232/CAN Bus

The relay protection system is an important component in transformer substation automation system. The communication that relaying with local monitor and distant manager makes substation automation successed, which reduced cost of protective and control equipment. In home RS422/RS485 is major way. Communication task, control and measure are complete by single CPU, which limited the development of performance. Developing communication converter between fieldbus and RS232, changing the communication way, meet new function demand in transformer substation and accord with market demand and national conditions. Because the technological advantage in performance, dependability, CAN has already become the world widely used fieldbus. This text through further investigation of CAN and relay protection system, develop the communication converter products of RS232/CAN.This text has described control technology of fieldbus, application of the fieldbus in relaying, CAN domestic and international studying situation at first, summarized the technological characteristic of CAN, including communication consults model, transmitting medium, format of message, structure of the frame, wrong type and location timing, etc.. Second, provide the design and implementation method of the hardware of communication converter. Adopts PIC18F248 as the master controller, realize the interface conversion between RS232 and CAN. Third, provide the software design and implementation method, including overall workflow, point-to-point CAN application layer protocol, CAN message acceptance filters and masks, CAN and RS232 interface software and treatment when message conflict. Fourth, give the function test method of communication converter lying in the transformer substation of JingShan town in NanJing county seat of FuJian province, summarize the performance of communication converter.The communication converter has put into field application. The running situation shows : The communication converter has already reached the designing requirement, has realized the relaying and local monitor's communication on CAN, at the same time to provide reference for other equipment inserts CAN bus.