| The insulated state is one of the most important problems of large power transformer safely running in power system. The most efficient method in monitoring the running transformer's insulated state is to extract partial discharge signals in real-time. In this paper, the essentiality of developing online partial discharge monitoring, the actuality and develop trend in home and abroad are discussed. In order to solve the problem in online monitoring system, a high effective detection PD circuit is designed, at the same time, wavelet transform and DSP technology are applied to improve capability in real-time process.Carry on electromagnetism and permit sex design to the power supply part first, analyzed the line form power supply and switch power supply to produce component and frame diagram of interference, immediately after main analytical each back track of the switch power supply creation interference of reason, include to commutate back track at a time and two times commutate back track, switch back track, control electric circuit and distribute electric capacity and the interference from power cable and charged barbed wire net;Finally analyzed to repress switch power supply the measure of the interference, include decrease interference the interference energy of the source, break and die down interference Zao a voice dissemination path, shield, reasonable of component layout and cloth line etc.Secondly, wavelet analysis is suit to extract break signal, so, it is programmed to implement the function of filter and signal extract.End, the electromagnetism of the structure system of PC board and system and permit a design:Totally build up 6 kinds of electric circuit models come analytical to importation signal, total mold interference signal and come from DSP chip internal interference signal of filter an effect, because of this text measure according to main Pin higher DSP application, the interference from DSP side the frequency be higher, and A/D sample frequency is 128:00/each cycle, consider system Gao the content is very low at 64 time Xie wave, adoption have no source two ranks filter wave then, in the high-speed DSP surroundings should also arrange to the Ou electric capacity nearby, the best method is to place them in the PCB first floor, is tightly tightly close together with spare part pin, in the meantime for let big electric capacity close to go to Ou electric capacity, put big electric capacity in the PCB crest layer. Adopt 4 laminations that the one side places a spare part, adopt an alternation to arrange inside the electric capacity of pit and I/O pin, so can make to lead line to the distance of its top electric capacity arbitrarily the most short. This kind of layout method can let to walk the line be the most short and the electric current back track be minimum, can also reduce radiation and live on to respond in the meantime.
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