A Research Of Mining Power Transform's Protective Relaying Equipment Based On DSP

The mining power transformer is very important equipment in coal mine safetyproduction system. The safe and stable operation of the power transformers aredirectly related to the normal and effective operation of coal mine. So, accordingto the parameters such as transformer capacity, it is necessary to research varioustypes of faults and not normal working conditions and then design wellperformance reliable equipment for mine transformer protection device.This essay based on a coal substation reconstruction for background. Firstly,discusses the mine transformer protection system's development situation andexisting problems, and focuses on the existing hardware problems of currentmine transformer protection device. According to the characteristics of DSP,choose DSP as the microprocessor for a transformer protection device. Secondly,author makes detailed study on some main aspects of transformer protectionprinciple of power transformers (over-current,overload,zero-sequence ofover-voltage and over-current,non electrical quantity). In order to meet thereal-time reflect and troubleshooting requirements, the design adopt a doubleDSP chip structure. The main protection and back-up protection are integratedinto one piece of called protecting DSP. Communication and control function areintegrated into another piece of called supervise and control DSP. The protecting DSP device independently completes all digital filter protection, algorithmimplement and export logic control CPLD. The supervise and control DSPcompletes some functions such as general start-up of device, man-machineinterface, ground communication. The advantages of this design can not onlyraise the fast and timely for device, but also ensure the equipment not because ofsupervise and control CPU plug in any spare part damages to cause theprotection mistake action. So this design can strengthen systematic reliability fordevice.Through the study of the microcomputer relay protection set's all kinds of figurearithmetic and DSP compute ability, the author present an improved algorithmbased on recursive Fourier algorithm. This algorithm can not only enhancesreal-time performance, but also have higher precision, better filtering effect andmoderate amount of calculation. At the same time, it is also can calculate thesolid and falsely department of fundamental wave. Then it can compute negativeelectric voltage, zero electric voltage power and the power direction withelectricity quantity.