The Design And Implementation Of Communicative Intelligent Circuit Breakers Based On Modbus

The development of intelligent of power grid further enhanced the intelligence requirements of power supply system, the traditional low-voltage circuit breakers can not meet the requirements of new applications, new generation intelligent and communicative low-voltage circuit breakers become the inevitable choice. To improve the intelligence level and have the communication capabilities, the key is to development and upgrading the core control unit intelligent controller and related communication protocol modules. This paper mainly developed intelligent controllers for low-voltage molded case circuit breakers and communication modules support Modbus protocol.(1) By analyzing the research and development trend in the domestic and overseas of low-voltage molded case circuit-breaker, according to prime design requirements of a new generation intelligent circuit-breaker, an implementation of communicative intelligent circuit-breaker based on Modbus protocol is given, also, the main functions and property indexes are given. The paper analyzed the key techniques related, such as three-phase protection technology,embedded real time operating system technology and Modbus fieldbus technology.(2) According to the basic functional and performance requirements of communicative intelligent controller, proposed the design of hardware system. Respectively given the design of hardware module, including microprocessor unit,power module,the signal acquisition module,memory expansion module,human-computer interface module and the debug module, and described the principle and realising method of each module. The software core of the intelligent controller is embedded real-time operating systemμC/OS-Ⅱ. The paper discussed migration ofμC/OS-Ⅱ, applications software design, such as data acquisition,three-phase protection,communications and other tasks in detail.(3) According to the basic functional and performance requirements of the Modbus communication modules, and refer to the relevant national standards, the paper described the hardware and software design and implementation of Modbus communication module. Power conversion, communication interface, address decoding and enable control hardware modules circuit schematic are given and analyzed in detail description. Software system design implementation flow chart are showed, as well as the implementation of Modbus protocol stack method, part of the code implementation and debugging of the module.(4) A testing platform was setted up according to the current technical condition and equipments. Performances and communication tests have been done, combined with the intelligent circuit-breaker,the electric operating mechanism,Modbus communication module and PC control software.Finally, the relevant test data were analyzed, testing shows that the system is stable and reliable, not only to achieve an accurate measurement and protection, but also have the functions of telemetry, remote control, remote communication, remote regulating, completely achieved the desired requirements.