Risk analysis of Geomagnetically Induced Current (GIC) in Power Systems
Abstract: Solar storms are a phenomenon that has a wide array of adverse consequences on technological systems, power systems in particular. During severe solar storms a geomagnetically induced current (GIC) starts to flow through long conducting structures, such as power lines and pipelines. The probability of solar storms has a roughly linear relation with the sunspot activity level which varies in 11 years cycles and at the moment of writing this thesis we are approaching the maxima of solar cycle 24. This thesis is a risk analysis of GIC in power systems and describes the causes and sources of GIC, the consequences, both on component level and on system level, and the likelihood of occurrence. When GIC flows through a transformer it causes the core to saturate, which leads to (a) increased reactive power consumption, (b) high levels of harmonics in the power system and (c) localized heating of the transformer. Point a and b are confirmed through simulations. High harmonics levels can cause protective relays to sense false fault conditions and trip. On a system level this can lead to (a) loss of production (b) local blackouts or (c) widespread blackouts. Localized heating of transformers can lead to permanent damage and spare parts and replacement units are associated with having long lead times. Communication and control systems are also subject to GIC and other solar storm related interferences. The thesis also contains a discussion about GIC risk associated to gas pipelines. The likelihood of solar storms is discussed and a method for determining the exceedance probability of extreme values for solar storms such as a 100-year storm is presented. The exceedance probability of a 100- year storm during 2012-2014 is estimated to 4.7%. Possible risk treatment strategies and forecasting capabilities are also briefly discussed, in order to briefly illustrate possible risk management schemes. This report should facilitate risk evaluation and provide the information needed to calculate quantitative risk values with respect to solar storms and power systems. In order to fully understand the extent of the consequences of a 100-year storm further studies are needed in order to take the complexities of covariance and the interconnectedness of different components and systems into account.
AT THIS PAGE YOU CAN DOWNLOAD THE WHOLE ESSAY. (follow the link to the next page)