Voltage Collapse Owing to Cascading Failures Under Geomagnetic Disturbances in Electromagnetic Transient Perspective

Under severe geomagnetic disturbances (GMDs) caused by intense solar activity, transformers in the power grid will generate groups of massive reactive power losses and harmonic currents. At the same time, harmonic currents can readily cause the mal-operation of relay protection device for reactive power compensation, which puts the power grid in a state of insufficient reactive power, leading to local reactive power imbalances. This may cause cascading failures and even voltage collapse, resulting in a large-scale power blackout. This article analyzes the mechanism and triggering conditions of cascading failures, proposes the development process of voltage collapse caused by sensitive equipment in the power grid. Based on this, the electromagnetic transient simulation of a four-station eight-node and IEEE 118-GMD grid was used to simulate the voltage collapse owing to cascading failures under GMDs, verifying the correctness of the proposed theory. Further, the occurrence patterns of cascading failures in the power grid during geomagnetic storms were summarized based on the simulation result, and the triggering conditions and influencing factors leading to voltage collapse were identified. This provides guidance for accurately and quickly identifying risk nodes during geomagnetic storms invasion to permit timely disaster prevention measures to avoid voltage collapse under GMDs.