Research On Magnetic Field Measurement Method And Its Application In The Detection Of Substations’Grounding Grids

Grounding grids intact for the safe operation of substation plays a crucial role, it not only provides reference potential public for various electrical equipment, but also can rapid excretion occurred, effectively reduce the surface potential anomalies when the system failure occurs lightning or short circuit, to protect the safety of persons and electrical equipments. However, due to the reasons of welding, corrosion, often caused by the grounding conductors broken, thinning defects. The grounding grids structure detection, fault diagnosis and condition evaluation of the transient electromagnetic method is researched, the main research contents are as follows:1. Based on the applied frequency current, realization method of grids structure and docking detection defect diagnosis by measuring the magnetic field distribution of grounding grids’ surface; proposes a method to detect the position of the grounding conductor and mesh network structure in the case of grounding grids’drawing missing or defect.2. Determine the best frequency-frequency current and the electric field intensity size by researching the means of theoretical calculations, modeling and simulation and experimental tests, combined substation actual topography, terrain and other factors affecting the surface of the punch and the degree of deviation from the coil and other factors on the measurement results.3. Improved the special pilot frequency power supply system by using high frequency pulse width modulation inverter power and push technology, developed a weak mobile signal-frequency magnetic field scanning system by low-noise preamplifier, band-pass filter, and so on, synchronization signals effectively measure the magnetic flux density and position information in the complex electromagnetic environment of substation.4. Substation grounding grids structure developed to detect and diagnose software defects based on labVIEW platform. Implementation of data acquisition, storage and analysis of integration and automation, improve the efficiency and accuracy of grounding fault detection and condition assessment.5. The diagnosis method and technology are tested and applied in practical substations and experiments in a testing grounding grid. The testing results show that this diagnosis idea is feasible, this diagnosis method is effective and this diagnosis technology is dependable.