Design Of Self-powered Relay Protection Device Based On STM32

Today,in China,with the rapid development of the national economy,both industry and technology have qualitative changes.Both industrial production and residential electricity consumption are constantly expanding,people's demands for the safety and reliability of the power system are more and more higher.If power system fails and cannot be repaired in time,it will cause users' property loss.While the relay protection device can protect the circuit in time.However it is not possible to provide power for the relay in some specific work environments.Based on this issue,the study designed the relay protection device which obtains electrical energy from measured circuit instead of providing a working power.This paper introduces the development of relay protection device and its development background.Based on the development trend of relay protection device and the actual working environment,a self-powered relay protection device based on STM32 chip is designed.In the design of the hardware circuit,the circuit is divided into power modules,data acquisition modules,communication modules and protection circuit modules.The power module provides the working power for the device;the data acquisition module converts the small current signal output by the current transformer into a voltage signal that the A/D chip can collect through the signal conditioning circuit;the communication module can realize the data exchange between the device and the upper computer to achieve remote control.Based on current data collected from A/D,protection module can estimate whether the circuit is failure,if the circuit has fault,it will protect the line.In order to calculate the current value of the circuit accurately,the Root mean square method and low-pass filter are used to process the collected data.Self-powered relay protection software is based on uC/OS-II operating system.According to the different functions of the software code,the software is designed into many modules such as data acquisition program,protection function program,communication program and power management program.Software modularity can enhance the readability,portability and real-time performance of the code.In the communication software design,MODBUS protocol is used to achieve data exchange.Finally,a series of hardware and software tests on the self-powered relay protection device are carried out.The results prove that the self-powered protection device designed in this paper has perfect functions and can completely realize the protection of the faulty line.