The Transient Magnetic Field Measuring Instrument Hardware Design And Implementation

The transient electromagnetic interference in the substation is a key issue that mayaffect the safe and stable operation of secondary equipment. The development of smartsubstation and digitized substation made the secondary equipment moved forward. Theproblem of transient electromagnetic interference between the primary equipment andsecondary equipment was even more prominent. Although existing transient magneticfield measuring devices can measure magnetic field within a certain amplitude rangeand frequency range, there are some defects of these devices that can not meet therequirements of transient magnetic field measurement in smart substations. Accordingto this issue, this thesis designed and developed a transient magnetic field recorderbased on magneto-resistance sensor. An Anisotropic Magneto-resistance sensor basedtriple-axis transient magnetic field probe was developed. The performances of therecorder were tested by simulating the magnetic environment in the laboratory. Thisthesis measured the magnetic field in a500kV substation by using the transientmagnetic field recorder. After that, this thesis discussed the magnetic shielding andconducted an experiment by using the transient magnetic field recorder. The maincontent of this thesis are as follows:1. Magnetic interference in substation caused by switching operation and fault wasassessed by simulation. Existing transient magnetic field measurement methodsand devices were discussed and then a new method based on magneto-resistance wasproposed.2. This thesis researched the implementation of magnetic field measurementdevice based on magneto-resistance effect. The AMR sensor based triple-axis probe andtransient magnetic field recorder was designed and developed. The measurement rangeof the recorder is-6Gauss to+6Gauss and the frequency range is DC to5MHz. Therecorder has functions as waveform displaying, data recording and data analysis, etc.3. Performances of the recorder were tested in the laboratory. Measurement andrecording of power frequency magnetic field, pulse magnetic field anddamping oscillating magnetic field were tested. 4. This thesis measured the magnetic field in a500kV substation of our country.Magnetic field data of several important positions such as high voltage bus, line inlet ofmain transformer and TCRGD were obtained.5. This thesis researched the low frequency and high frequencymagnetic field shielding theory of different metals. Experiments on the magneticshielding effect were conducted to verify the shielding effectiveness of severaldifferent metals.