Simple Geomagnetic Induced Current Detection and Monitoring in Power Transformers

This paper presents a detection system of geomagnetic induced currents based on the measurement of the magnetic field outside the magnetic core; it is possible to evaluate the core operating conditions of power transformers under the effect of geomagnetic induced currents. The nonlinear behavior of the core due to asymmetric saturation produces a distortion in the external magnetic field which can be evaluated by the measurement of the magnitude of even harmonics; we describe the experimental setup and the instrumentation required for real-time detection of asymmetric saturation caused by quasi-DC magnetic fields. The experimental results obtained by simulating the presence of geomagnetic induced currents are presented.