The presentation generated many questions from the audience that I did not have time to address. This blog post addresses a few of those questions. Stay tuned for more posts, with more questions and answers.
Question: Can a Geomagnetically Induced Currents (GIC) event knock out a substation?
Answer: The Hydro Quebec and other previous storms have shown that substations can experience forced outages. Past events have shown station loss can occur due to relay or SVC control misoperation, or lack of system VAR support. This is due to the large increase in VAR consumption and harmonic generation during GIC flow. However, immediate transformer failure causing a forced outage during a storm due to thermal damage is very unlikely, unless the transformer is already compromised due to old age or previous thermal degradation.
Question: Are there transformers failures because of GIC?
Answer: The literature cites a few cases where transformer thermal damage has been attributed to GIC. These cases indicate that the transformers in question were removed from service after the geomagnetic disturbance (GMD) event. However, Siemens is not aware of any particular case where a forced outage or failure of a transformer due to GIC current has occurred during a GMD event.
Question: You said that we are in a cycle 24 peak. If you were a betting man, what month and year would you predict the next GMD might happen? Is Siemens ready with replacement transformers with short delivery times?
Answer: NOAA-issued chart of observed sunspot activity predicts the present sunspot cycle will peak sometime during 2nd or 3rd quarter of 2013. However, it is impossible to predict with current space science when the next solar storm could strike earth. Solar storms do not always correspond to solar sunspot maxima. Also, note that our primary concern is only with the small fraction of coronal mass ejections that are precisely oriented to impact earth. As a result, solar storm occurrences and their effects must be treated as probabilistic events.
Siemens does not have a fleet of ready transformers since they are custom-made and tailored to each user’s specific requirements. However, we would be pleased to review customer requirements and needs in order to offer the best possible deliveries. With 22 plants worldwide, Siemens has exceptional capacity to meet customer demands.
For the latest update on this topic:
NASA just reported that another coronal mass ejection erupted from the Sun last Thursday. Read a description of the event with video.