Study On Preventing Override Trip System Under Coal Mine Electric Network Based On The CAN Bus

The Coal mine underground power system mostly pick with the copper core short electric cable to supply the current transmission, the impedance is small, the differences of short circuit magnitude at all levels is very small, Relay Protective is hard to set ,and coal mine shaft protective device does not renew promptly, or Environmental Considerations, exists insensitive action,poor validity,the parameter is hard to adjust, bad precision ,etc. Also , the design proposal of the traditional tripping protection has certain flaw, those cause Line Protection to be easy to have the misoperation and Override Trip incidents, leads to Large Area Blackout in the Coal mine underground power system.Aimed at this case, this paper uses the CAN Bus to have the prominent reliability, timeliness and flexibility in the data communication, and long transmitting distance, excellent the correcting ability, and very effectively constitutes distribut control system. Designed preventing Override Trip system under coal mine electric network based on the CAN bus by slightly transforming the tradition protective device to carry on the accuracy control, realize each protective device to coordinate. When breaking down, controls all levels of protections to use the corresponding movement mutually, satisfies the selectivity and fast breaking nature of all levels of protections, provides the possibility to prevents Override Trip.This article first analyses system to achieve standards in the concrete function in application, introduces as a whole system's structural feature and operation principle, schemes how to realize each part function of system ,and technical index that system should achieve. Then gives the detailed methods about the design of the hardware and software. On the hardware design of the system, chooses the 89c51 Single—chip Microprocessor Minimum System ,The external circuit,Photocouplers,A/D conversion circuit,Signal Adjust Circuit,and Trip Circuit to constitute microcontroller. Designs interface hardware to be used to communicate between each Microprocessor and Supervisory PC by CAN bus. At the same time chooses the 89c51 Single—chip Microprocessor Minimum System as processor of the Microprocessor, CAN controller chooses SJA1000, CAN bus sender/receiver chose PCA82C250.In supervisory system design, to cause the design of system is easy to realize, design and debug, Supervisory PC is still to select the 89c51 Single—chip Microprocessor and above integrates with LED lightings drived by the 74HC595 chip and HE1205B electromagnetic buzzer. In the software design, according to the CAN2.0B standard, system's correspondence application layer agreement picks with"the ID+ order + data"the form as communication protocol ,and picks with 51 Assembler languages to design CAN communication node receive-send processes, alarm process and system main program. Finally built simulation experimental platform to carry on the hardware debug and CAN node receive-send experiment, finally discusses the laboratory procedure and method in detail to the system protection reliability and correspondence time and result is testified by the experiment.