| Along with the rapid development of our country’s electric power system and the unceasing expand scale of the power grid scale, the smart power grid technology has been gradually matured and pushed to the market. The implementation of the smart power grid has also put forward the higher request to the middle and low voltage power line distribution protection. Currently widely used circuit breaker intelligent control equipments widely use32bit DSP, although it can meet the requirement of the current power system protection. With the expansion of the smart power grid’s scale, these equipments gradually cannot make the power grid parameter measure more accurately and troubleshoot more faster. After a large number of research to the products of the same type at home and abroad, this topic summarized the advantages and disadvantages of the different production and combine these with the development trend of low voltage transmission line protection device, in order to develop a double CPU structure based on DSP and ARM, which had the function of power grid frequency witg low voltage circuit breakerintelligent control device. This device which would set measure、protection、control、communication and other functions in a body, would have the open protection parameter structure at the same time. These advantages could make this device be easily applied to different occasions.Firstly this paper analyzed and designed the hardware structure according to the function classification, identifies the double CPU structure which regarded LPC2132and TMS320F2812as the core processor, and at the same time made the necessary design and simulation analysis to Synchronous sampling simulation module、Frequency detection module、Switch input/output modules、Man-machine interface and communication module. Through modular hardware design, the whole device could be divided into analogue part、digital part and driving part. They connected with flexible flat cable.This method reduced the interference of digital circuit on analog circuit.Secondly, this paper analysed the parameters’s mathematical model of the different power grid and made a use of the power grid parameter which had the DC decay component and be calculated by the full wave Fourier algorithm. This paper carried on the detailed analysis of many algorithm including three-step current protection algorithm、inverse time zero sequence current protection algorithm and voltage protection algorithm, and gave the DSP programming flow chart. Except for the protection algorithm, this paper also made brief analysis to the device of man-machine interface、RS-485communication and failure treatment, and gave the flow chart. The whole software programming used the ideas of modularity and each protection module or function module was written into the independent function unit, making the debugging and test by software conveniently.At the same time, this paper also put forward the improvement of switching strategy, new strategy can effectively suppress the overvoltage and surge current and improve the protection of the reliability of the system, reduce the possibility of misoperation.Finally, this paper realized the prototype production of the circuit breaker intelligent controller through the prototype hardware manufacturing and the software testing. This paper also realized the required function of this paper, including power grid parameter measurement、 transmission line protection、the man-machine interface and RS-485communication. It could be obtained from the test data that this design whose idea was clear and reliable, accuracy of measurement was high and protection action was quick has achieved desired effect... |
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