Processing Magnetometer Signals for Accurate Wide-Area Geomagnetic Disturbance Monitoring and Resilience Analysis

Geomagnetic disturbances (GMDs) can disrupt the operation of power systems by inducing a quasi-dc voltage and generating geomagnetically induced currents (GICs) in a vast area of the power systems. This gives rise to the importance of wide-area monitoring of magnetic field on earth's surface. Assessment of power system resiliency against GMDs requires an accurate calculation of GIC flows, which is achieved by wide-area monitoring of the magnetic field <italic>B</italic>, and processing the <italic>B</italic> signals that are recorded by magnetometers on the earth's surface. In this paper, a method is proposed to denoise the <italic>B</italic> signal. Spikes in the signal are detected using a stationary wavelet transform and then replaced. Time derivative of <italic>B</italic> signal is taken by a continuous wavelet transform to prevent amplification of the noises. Furthermore, a quantitative analysis is performed to detect the optimum sampling frequency to overcome the practical limitations associated with transmitting the recorded <italic>B</italic> signal and to modify peaks of <inline-formula><tex-math notation="LaTeX">${\boldsymbol{dB}}/{\boldsymbol{dt}}$</tex-math></inline-formula> signal negligibly. It is demonstrated that a sampling frequency of 1/15 Hz satisfies these conditions. Finally, GICs in a 118-bus benchmark power system are calculated with respect to a realistic geomagnetic storm to demonstrate the effectiveness of the proposed signal processing method.