Research Of DC System Grounding Detection Device In Embedded System Based On ARM

Embedded system has already been extensively applied to many fileds, because it has the outstanding characters of strong performance, low power consumption, high reliability and facing application. 32 bit RISC processor, produced by ARM Company, which has many excellent performances, has already become RISC standard of the embedded solution.It is important for safe operation of power system that DC system grounding fault in power plants and transformer substations is detected timely and exactly. The method of low frequency signal injection, which is widely used, is easily influenced by the capacitors between ground and each branch. Because of its eminent characteristic of time-frequency analysis, wavelet transform is used to analyze and dispose the signal of branch current; thereby the influence of the capacitors could be resolved effectively. The former detecting devices are mostly designed based on SCM, which limits the use of advanced algorithms based on wavelet transform. The paper attempts to apply embedded system into DC system grounding detection, utilize its advantages of high performance, high stability and real time and realize the detection method based on wavelet transform. The main contents of the research include:1,Design of hardware system: integrated scheme and interface of the units; MPU control unit: according to requirement of the subject, choose the appropriate MPU and expand peripheral components to accomplish control of signal collection unit and realization of wavelet algorithm; signal collection unit: including grounding insulated monitor, voltage and signal disposal circuit, choice of branch currents and voltages, production and loading of low frequency signal, to realize sample, disposal of DC system signal and take over the instruction of control unit; control key and display unit: realize control of MPU unit and display running states of detection device.2,Design of software system: rootμC/OS-II operating system to S3C44B0X; develop the startup program for S3C44B0X; realize the system application program according to DC system grounding detection principle based on wavelet transform.3,Validate the program: in the embedded system based on S3C44B0X+μC/OS-II, prove the detection method based on wavelet transform, realize schedule of multitasks and calculate the grounding resistance to distinguish grounding fault of branch; finally, develop program for peripherals correspondingly. The research of the paper attempts to choose ARM processor to carry through embedded system development and design application program, realize an integrated DC System Grounding Detection Device, which is meaningful for use of embedded system in industrial control field.