On Accurate Location Of Power Cable Faults And Its Background Noise Reduction Technology

Eco-city is a new concept of modern city construction.People pay more and more attention to the utilization rate and aesthetics of space resources.The overhead lines used to transmit power resources have been gradually replaced by power cables.The difference is that power cables are mainly laid underground,which may malfunction due to aging,overload or accidental construction damage,which will have a huge impact on social life and industrial production.Therefore,it is of great significance to detect the fault location of underground power cable as soon as possible.Power cable fault detection includes pre-positioning and precise locating points.This thesis mainly takes precise locating points as the background,aiming at designing the precise locating detection system of double-sensor power cable,and studying the effective method of background noise reduction for the sound signal collected during fault detection.Firstly,the technology of power cable fault detection is studied,and the specific steps of power cable fault detection are clarified.The precise determination point process usually needs to use high-voltage signal generator to break through the faulty power cable.According to the characteristics of the sound and pulse magnetic field signals generated by the impact discharge,the appropriate method can determine the path of the power cable and detect the position of the fault point.Then,the commonly used path and the precise point detection method are studied.The acoustic magnetic synchronization method has higher precision than other precise point detection methods,but the impact discharge sound is often affected.It is difficult to detect the noise interference in the environment.It is difficult to effectively remove the non-stationary noise interference while taking into account the original impact discharge sound quality.Combining the characteristics of impulsive discharge sound signal,a background noise reduction technology based on wavelet transform and Independent Component Analysis(ICA)is proposed,The simulation and field data acquisition test of MATLAB prove that the algorithm can effectively reduce the noise of impulse discharge noise with noise.Then,a precise fixed-point detection system of double-sensor power cable is built,and the design of hardware circuit and the programming and debugging of software program are completed..The system integrates the two methods of acoustic and magnetic synchronization and step-voltage method,through two piezoelectric sensors and horizontal and vertical placement.Acoustic,magnetic and voltage signals are received by two piezoelectric sensors and two electromagnetic induction sensors placed horizontally and vertically and step-voltage metal probes,and after being processed by the signal conditioning circuit,they are converted into digital quantities by an A/D converter and transmitted to the core processor for digital signal processing,realize the judgment of power cable path,combine the background noise reduction,the time difference of sound and magnetic time and the voltage of stride voltage,and output them to the headphones and LCD display.Finally,the effectiveness of each part of the dual-sensor power cable precise point detection system designed in this thesis is verified by field experiments,which shows that the system can find the location of the fault point accurately.