Design Of Partial Discharge Online Collecting System For Transformers Based On DSP

The dissertation presents an online partial discharge(PD) collecting system of large power transformers based on digital signal processing(DSP).It gives an analysis of the partial discharge signal's characteristics and properties.According to the fundamental of the Rogowski coil current sensor,the homotactic model of high frequency pulse sensor is established in the paper.It discusses the effects of the coil's dimension parameters(D,d), sensor coiling number(N),stray capacitance(C₂) and loading resistance(R₂) on pass-band width and sensitivity by Simulated Analysis in Matlab.Then the sensor is designed and the choice method of the optimal parameter of the sensor has been summarized and proposed.The design of the prepositive Conditioning system,which is consist of preamplifiers, polarity discrimination circuit,alternative band-pass filter and postamplifiers,is given in the paper.According to the principle of polarity discrimination and analogue filtering,the prepositive conditioning circuit can inhibit the most of the noises and undesired signals except the white noise in the pass-band of filter.Meantime,the Signal-to-Noise Rate is able to be increased by differentially amplifying.The dissertation gives the design of the high speed data collection system,which is made up of programmable amplifiers(AD8250),A/D converting circuit(AD9224),phase synchronization circuit,digital signal processor(DSP,TMS320F2812) and module of communication.According to the idea of 'Fast Collecting Slow Transmitting' and 'Time-sharing Collecting',the output signals of long transmitting are amplified to meet the need of A/D,which turns analog input to 12-bit digital signals for DSP.The samples of signal which are one-to-one related to the phase are written into a 512K×16 Asynchronous SRAM until a power frequent period is over.Finally,CPU sends them to PC for further processing by module of communication.