Design And Implementation Of Substation Remote Terminal Unit

In recent years, because power networks become increasingly large and complex, a large number of nonlinear devices and high power equipments, inverter devices are in use, which makes the stability and reliability of the power grid under threat, so the real-time monitor and control the running status of transformer substation becomes particularly important. In the field of substation automation, the development of intelligent electrical, in particular such as intelligent switch and photoelectric mutual inductor, electromechanical integration equipment, and the development and application of computer in the high-speed network and real-time system, provide a theoretical and technical foundation for all information collection and transmission intelligently in the transformer substation, at the same time the performance requirements of remote terminal unit also becomes more and more high. As the traditional RTU based on single chip microcomputer cannot meet the requirements of high-speed, real-time, remote communication, etc, so the paper puts forward a high-speed, multi-channel, diversity of communication’s RTU solution based on processor STM32F207. Adopting multi-channel analog switch selection techniques and IO port extension technology, the acquisition channel number of RTU increases under the condition of limited hardware resources.This paper first introduces the development course and trend of RTU, compares and analyzes all kinds of RTU solution, determines the design scheme of remote terminal unit based on STM32F207. Then according to the functional requirements, the paper designs the RTU hardware modules and the hardware overall composition block diagram, and analyzes the working principle of each module circuit, including the choice of multi-channel analog switch circuit, signal modulation circuit, I/O port extension circuit, RAM extension circuit, communication interface circuit. Then, on the ARM MDK integrated development environment software platform, in accordance with the modular and hierarchical design thought, the paper designs each software module, mainly introduces the RTU’s ac sampling algorithm principle and concrete implementation, and uses modbus protocol as communication protocol. Finally the paper sets up a test platform for the RTU, various properties test of RTU has carried on by professional RTU tester, puts the test data and theoretical data to contrast, and calculates the relative error, and analyzes the causes of error. Test and practical application show that the design of the substation remote terminal unit based on STM32F207is stable and reliable running, high sampling precision, fast response and has good market prospects.