Research On Large Dynamic Range Acquisition Method Of Power Grid Fault Pulse

With the continuous development of grid fault location technology,more and more intelligent location algorithms are applied to fault location,positioning efficiency is greatly improved,and the requirements for the dynamic range of data collection are also increasing.However,existing acquisition devices have insufficient resolution for small signals and cannot meet the requirements of fault location technology.In order to improve the dynamic range of fault traveling wave acquisition,this thesis proposes the use of logarithmic amplifier compression properties to compress the fault traveling wave in real time,and studies related technologies.The main work is as follows:(1)A large dynamic range data acquisition scheme based on logarithmic amplifier is studied.According to the requirement of the scheme,a low noise solution is proposed.A low-noise preamplifier circuit is introduced in the pre-stage of the logarithmic amplifier circuit to reduce the noise level of the circuit.(2)The noise characteristics of the preamplifier circuit and the influence of the sensor parameters on the circuit noise figure are analyzed.According to the specific parameters of the circuit and the sensor,the total output noise voltage of the front-end circuit is 26.4?V.The voltage noise of the op amp and the thermal noise of the feedback network resistor dominate the circuit.(3)According to the bipolarity of the fault signal,a two-way acquisition scheme was proposed.And designed a specific circuit,analysis of the signal conditioning circuit,logarithmic circuit and analog-to-digital conversion circuit indicators.Finally,the simulation and analysis of each module and the overall circuit are carried out.The results show that this scheme can achieve large dynamic range acquisition,which has certain reference value for the fault acquisition and fault location of the power grid.