Design Of Protection Module Of Intelligent Pole-mounted Switchgear Controller Based On Embedded Operating System

For there are various types of pole-mounted switchgear in service, the universality and compatibility of controllers are hard to achieve. For this reason, a protection module of universal pole-mounted switchgear controller which is capable of current and voltage signal sampling and operation signal output was designed in this study. By using the Samsung development board which is based on S4C2440 processor with ARM920 T core, a development and test platform for protection was designed. The platform is ported to the Linux for embedded system, analog signal sampling, operation, logical judgment, controlling of switching value input/output and communication functions were realized cross multi-thread technique. The protection programs were developed as applications which were installed in Linux operation system. The protection function can be configured and updated flexibly and conveniently, which make the controller can control different types of pole-mounted switchgears and fulfil requirement of different distribution automation solutions, and then achieve its universality.For the algorithm selection, sampling algorithms including two points product algorithm, half-cycle integration algorithm, differential operation and all wave Fourier algorithm were studied, and the operation speed, accuracy and filtering quality were compared.For the program design of protection, by using the Linux for embedded system and Qt development platform, functions were realized including the three-section and zero-sequence current protection for pole-mounted circuit breaker, the reclosing function for pole-mounted recloser, voltage-time/current-count/current-voltage sectionalizer for pole-mounted load switch. The controller interface and the function of automatic inquiry and download for install/update files were designed based on FTP agreement.A distribution network model was built on MATLAB/Simulink and types of faults and faults waveforms caused by automation distribution solutions were simulated. The fault waveforms were imported to protection module installed on the 10 k V vacuum circuit breaker by a signal generator. According to the test results, the protection module can function properly and drive the circuit breaker under all types of fault waveforms.