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Register a new userStatistical Analysis of the Correlation between Anomalies in the Czech Electric Power Grid and Geomagnetic Activity
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Eruptive events on the Sun have an impact on the immediate surroundings of the Earth. Through induction of electric currents, they also affect Earth-bound structures such as the electric power transmission networks. Inspired by recent studies we investigate the correlation between the disturbances recorded in 12 years in the maintenance logs of the Czech electric-power distributors with the geomagnetic activity represented by the K index. We find that in case of the datasets recording the disturbances on power lines at the high and very high voltage levels and disturbances on electrical substations, there is a statistically significant increase of anomaly rates in the periods of tens of days around maxima of geomagnetic activity compared to the adjacent minima of activity. There are hints that the disturbances are more pronounced shortly after the maxima than shortly before the maxima of activity. Our results provide indirect evidence that the geomagnetically induced currents may affect the occurrence rate of anomalies registered on power-grid equipment even in the mid-latitude country in the middle of Europe. A follow-up study that includes the modelling of geomagnetically induced currents is needed to confirm our findings.
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Eruptive events of solar activity often trigger abrupt variations of the geomagnetic field. Through the induction of electric currents, human infrastructures are also affected, namely the equipment of electric power transmission networks. It was shown in past studies that the rate of power-grid anomalies may increase after an exposure to strong geomagnetically induced currents. We search for a rapid response of devices in the Czech electric distribution grid to disturbed days of high geomagnetic activity. Such disturbed days are described either by the cumulative storm-time $Dst$ or $d(textit{SYM-H})/dt$ low-latitude indices mainly influenced by ring current variations, by the cumulative $AE$ high-latitude index measuring substorm-related auroral current variations, or by the cumulative $ap$ mid-latitude index measuring both ring and auroral current variations. We use superposed epoch analysis to identify possible increases of anomaly rates during and after such disturbed days. We show that in the case of abundant series of anomalies on power lines, the anomaly rate increases significantly immediately (within 1 day) after the onset of geomagnetic storms. In the case of transformers, the increase of the anomaly rate is generally delayed by 2--3 days. We also find that transformers and some electric substations seem to be sensitive to a prolonged exposure to substorms, with a delayed increase of anomalies. Overall, we show that in the 5-day period following the commencement of geomagnetic activity there is an approximately 5--10% increase in the recorded anomalies in the Czech power grid and thus this fraction of anomalies is probably related to an exposure to GICs.
English: Solar eruptive events affect the close neighbourhood of the Earth. They also affect human infrastructure, power grids mainly, due to the induction of electrical currents. Only recently the attention was drawn not only to large flares, but also to estimate the long-term effects of increased solar activity by statistical methods. We analyse the failure rates in the main Czech power transmission system operated by the Czech national operator v{C}EPS. We show that the effects of solar activity on failure rate in the main Czech power grid cannot be excluded even for central-european country. This is a preliminary study. Czech: Eruptivni projevy slunev{c}ni aktivity ovlivv{n}uji bezprostv{r}edni kosmicke okoli nav{s}i Zemv{e} a postihuji prostv{r}ednictvim indukce elektrickych proudr{u} i pozemskou infrastrukturu, zejmena rozvodne sitv{e} silove elektv{r}iny. Teprve v poslednich letech byla vv{e}novana pozornost nejen hodnoceni bezprostv{r}ednich dopadr{u} silnych eruptivnich udalosti na zav{r}izeni rozvodne sitv{e}, ale take statistickemu zhodnoceni vlivu zvyv{s}ene slunev{c}ni aktivity. Ve spolupraci s v{C}EPS, a.s., jsme statisticky vyhodnotili v{c}etnost zavad na zav{r}izenich patev{r}ni rozvodne sitv{e} v{C}R v zavislosti na urovni slunev{c}ni aktivity a ukazujeme, v{z}e vliv nahlych eruptivnich udalosti na zavadovost zav{r}izeni v{c}eske rozvodne sitv{e} nelze vylouv{c}it.
Geomagnetically induced currents (GICs) are a well-known terrestrial space weather hazard. They occur in power transmission networks and are known to have adverse effects in both high and mid-latitude countries. Here, we study GICs in the Irish power transmission network (geomagnetic latitude 54.7--58.5$^{circ}$ N) during five geomagnetic storms (06-07 March 2016, 20-21 December 2015, 17-18 March 2015, 29-31 October 2003 and 13-14 March 1989). We simulate electric fields using a plane wave method together with two ground resistivity models, one of which is derived from magnetotelluric measurements (MT model). We then calculate GICs in the 220, 275 and 400~kV transmission network. During the largest of the storm periods studied, the peak electric field was calculated to be as large as 3.8~V~kmtextsuperscript{-1}, with associated GICs of up to 23~A using our MT model. Using our homogenous resistivity model, those peak values were 1.46~V~kmtextsuperscript{-1} and 25.8~A. We find that three 400 and 275~kV substations are the most likely locations for the Irish transformers to experience large GICs.
We use the am, an, as and the a-sigma geomagnetic indices to the explore a previously overlooked factor in magnetospheric electrodynamics, namely the inductive effect of diurnal motions of the Earths magnetic poles toward and away from the Sun caused by Earths rotation. Because the offset of the (eccentric dipole) geomagnetic pole from the rotational axis is roughly twice as large in the southern hemisphere compared to the northern, the effects there are predicted to be roughly twice the amplitude. Hemispheric differences have previously been discussed in terms of polar ionospheric conductivities, effects which we allow for by studying the dipole tilt effect on time-of-year variations of the indices. The electric field induced in a geocentric frame is shown to also be a significant factor and gives a modulation of the voltage applied by the solar wind flow in the southern hemisphere of typically a 30% diurnal modulation for disturbed intervals rising to 76% in quiet times. Motion towards/away from the Sun reduces/enhances the directly-driven ionospheric voltages and reduces/enhances the magnetic energy stored in the near-Earth tail: 10% of the effect being directly-driven and 90% being in tail energy storage/release. Combined with the effect of solar wind dynamic pressure and dipole tilt on the pressure balance in the near-Earth tail, the effect provides an excellent explanation of how the observed Russell-McPherron pattern in the driving power input into the magnetosphere is converted into the equinoctial pattern in average geomagnetic activity (after correction is made for dipole tilt effects on ionospheric conductivity), added to a pronounced UT variation with minimum at 02-10UT. In addition, we show that the predicted and observed UT variations in average geomagnetic activity has implications for the occurrence of the largest events that also show the nett UT variation.
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Gabriela C. Martins
, Leonardo S. Oliveira
, Fabiano L. Ribeiro andn Fabricio L. Forgerini
2016
Power Grids and other delivery networks has been attracted some attention by the network literature last decades. Despite the Power Grids dynamics has been controlled by computer systems and human operators, the static features of this type of network can be studied and analyzed. The topology of the Brazilian Power Grid (BPG) was studied in this work. We obtained the spatial structure of the BPG from the ONS (electric systems national operator), consisting of high-voltage transmission lines, generating stations and substations. The local low-voltage substations and local power delivery as well the dynamic features of the network were neglected. We analyze the complex network of the BPG and identify the main topological information, such as the mean degree, the degree distribution, the network size and the clustering coefficient to caracterize the complex network. We also detected the critical locations on the network and, therefore, the more susceptible points to lead to a cascading failure and even to a blackouts. Surprisely, due to the characteristic of the topology and physical structure of the network, we show that the BPG is resilient against random failures, since the random removal of links does not affect significantly the size of the largest cluster. We observe that when a fraction of the links are randomly removed, the network may disintegrates into smaller and disconnected parts, however, the power grid largest component remains connected. We believe that the even a static study of the network topology can help to identify the critical situations and also prevent failures and possible blackouts on the network.
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