Design And Development Of 35kV-line Microprocessor Integrated Protection Device

Since human society entered the age of electricity,electrical energy has become an important pillar in economy.At the same time,the scale and complexity of the power system have also been constantly expanded.To maintain reliable and stable supply of electric energy,microcomputer protection devices were developed.However,with the improvement of the system voltage level and the development of the mode of protection and decentralization,the requirements on the performance and reliability of the microcomputer protection device are also continuously raised.Therefore,it is necessary to develop a microcomputer protection device with perfect performance,high stability and reliability,cost-effective.This thesis is based on the development trend of microcomputer protection and the problems during the period of using microcomputer protection by power equipment companies,then we designed a multi-function microcomputer protection device with high-performance STM32F407VET6 microcontroller,below the voltage of 35kV.By analyzing requirements of the project,the hardware structure,functional modules,the selection of the chip and the design of the software scheme are determined.This design adopts hardware modularity design technique and software layering design technique,which not only realizes the functions required of the device,but also greatly improves the expansibility and maintainability of the device function.In hardware,using cost-effective STM32 F4 high-performance MCU STM32F407Vet6 as the core hardware structure and using the signal acquisition module,the switch value module,power-supply module and the human-computer interaction module hardware overall program design as the assistance,which give a more detailed introduction of the various functional modules circuit design and some demonstrative simulation experiments.In software,adopting the method of hierarchical design,firstly introducing the bottom of the driver,then discussing the use of μC/OS-II real-time operating system,and finally analyzing the application layer from the angle of view,the main application program of the device is introduced.In the aspect of software algorithm,by comparing several common sampling algorithms and digital filters,the differential digital filter and full-wave Fourier algorithm are combined to realize the sampling of voltage and current signals.Finally,this article combines the research and countermeasures against interference in the design of this device,introducing the sources and ways of common interference and the anti-interference measures that can be applied in practice.A variety of tests were performed on the prototype of the device,including accuracy measurement,protecting sensitivity,protecting delay,and EMC test(4kV/100kHz electric fast burst test).The experimental results show that the device meets the requirements of the project design requirements,and in terms of anti-interference,meeting the national EMC requirements for power products.