Chapter 16 - Geomagnetically Induced Currents: A Threat to Modern Power Systems

Abstract

Geomagnetically induced currents (GICs) are a potential threat to power system stability and availability. The inclusion of particular elements in the power system can optimize the resilience of the system to this threat. The flow of GIC through transmission lines and transformers across a power network could have negative consequences. These include an increase in the reactive power demanded by GIC-laden transformers, transformers operating within the region of nonlinearity due to half-wave saturation, excessive heating in transformers leading to thermal damage, malfunction of transmission line protection schemes, and voltage problems in affected sections of the network. The literature on GICs originally dealt with GICs in power lines in high-latitude countries where GICs are most likely to occur. This includes research on GICs in high-latitude countries such as Finland and in Canada, where the March 1989 geomagnetic disturbance plunged millions of Canadian inhabitants into darkness. GIC-related damage to power systems can occur in mid- and low-latitude regions (as reported in papers about GICs) in South Africa, Scotland, Brazil, Spain, China, Japan, New Zealand, and Australia. Highly interconnected power networks—which is characteristic of modern power systems—with long transmission lines are most susceptible to high GICs, as research has proven. When coupled with the heavy dependence of the economy on a reliable electrical power network, it becomes evident that GICs are a new challenge to modern power system operation and planning. This book chapter will discuss space weather as the root-cause of GICs, the effect of GICs on power system components such as transformers and protection devices, and the threat caused to the security of power supply. It will explore methods for estimating GICs in power lines, and present methods for the mitigation of the impact of GICs on power systems.