Geomagnetic disturbance effects on power systems

The trends in interconnected power systems and the equipment to transmit and control power flows and system voltage profiles have made power systems more susceptible to geomagnetic disturbances (GMDs). A summary is presented of the state of knowledge and research activity to the present time on GMD/geomagnetically induced currents (GICs) phenomena, transformer effects, the impact on generators, protective relay effects, and communication system effects. Other topics addressed include modeling and predicting GIC, measuring and monitoring GIC, mitigation methods, system operating guidelines during GMDs and alerting and forecasting procedures and needs for the power industry.<>