The Research And Application Of Real-time CDT Protocol In DC Screen

With the popularity of the comprehensive construction of national smart electric powerand network technology, the dispatching automation equipment requires higher ability ofdata communication and security analysis. CDT (Cyclic Digital Transmission) is the remotecommunication protocol which is applied most widely in our country at present amongmonitoring system of power station computer and data acquisition of dispatch center andcommunication of monitoring equipment. Its application in DC screen mainly realizes datacommunication between DC screen monitoring module and other modules and the back endserver. However, in fact, because of lacking necessary research, the DC screen equipmentmanufacturers often cut down the CDT protocol based on the function requires of their ownequipment, which cause bad influence for forming a market uniform interface standard andequipment upgrades. In addition, in the face of increasingly powerful data, the software andequipment based on the common MCU is getting lower and lower in real-time andreliability.According to the discussion above, based on the kernel mechnism of μC/OS-II, whichis widely used in the environment of parallel multitask communication via messages andemails, we made a profound study for the real-time application of the CDT protocol, whichis realized on a32-bit development board designed for a DC screen system. This work isvery important and has practical significance.The paper firstly summarizes the development of the electric power dispatchingautomation system, and contrastively describes several domestic common communicationprotocols. Secondly, the format and transmission rules of CDT protocol are analyzed indetail, planted μC/OS-II on a32-bit LPC1788chip, and realized multitask synchronousparallel communication and scheduling method under the CDT protocol master-slave modein DC screen. And then, we designed a monitoring module core board based on the researchand experiment. In addition, to improve the accuracy of unified time reference for datacommunications between different devices, a GPS timing module is designed andimplemented. Through the close combination of basic theory and project practice, the research workgets good results. The result of communication test in the DC screen produced by a electriccompany shows that the application of CDT protocol in dispatching and monitoring moduleis timely and stably. Currently, this module has been applied in several kinds of DC screensystems in power substation.