Efeitos do Sol nas Redes Elétricas

Kepler de Souza Oliveira Filho

http://astro.if.ufrgs.br

Correntes induzidas

If a Coronal Mass Ejections passes the Earth, it penetrates into the Earth's magnetosphere and cause currents of a million Amperes or more arise in the Earth's ionosphere. These ionospheric currents, called electrojets, induces a varying magnetic field and thereby an electric field in the surface of the Earth. The electric fields drives semi-direct currents through the transformers neutrals and the power lines connecting them. If it exceeds about 50 Ampere, there might be some disturbances in the power system.

Geomagnetically Induced Currents

Geomagnetically induced currents (GIC) are driven by the electric fields produced by the magnetic field variations that occur during a geomagnetic disturbance. Because of their low frequency compared to the AC frequency, the geomagnetically induced currents appear to a transformer as a slowly-varying DC current. GIC flowing through the transformer winding produces extra magnetisation which, during the half-cycles when the AC magnetisation is in the same direction, can saturate the core of the transformer. This results in a very spikey AC waveform with increased harmonic levels that can cause misoperation of relays and other equipment on the system and lead to problems ranging from trip-outs of individual lines to collapse of the whole grid.

Saturation of the transformer core produces extra eddy currents in the transformer core and structural supports which heat the transformer. The large thermal mass of a high voltage power transformer means that this heating produces a negligible change in the overall transformer temperature. However, localised hot spots can occur and cause damage to the transformer windings.

The costs to power system operators involve not only replacement of damaged equipment but also the loss of revenue from sale of power. The Quebec blackout on March 13, 1989 had a net cost of about $13.2 million; damaged equipment accounts for about $6.5 million of that estimated cost. The transformer at the Salem, New Jersey, nuclear generating station, that burnt-out during the March 13, 1989 magnetic disturbance, cost several million dollars to replace. Such expensive units are usually built to order and the delivery time is normally about one year. Unusually, in the Salem case, a replacement transformer was available and delivery and installation took only 6 weeks. Even so , having the transformer out of service restricted the power that could be delivered from the Salem generating station and the purchase of replacement power from neighbouring utilities cost about $17 million, far more than the cost of the transformer.

Efeitos

Transformador em New Jersey

GSU (generation step-up) transformer at a nuclear plant in New Jersey in which a 1,200 MVA, 500kV bank was damaged beyond repair

GIC medido na Finlândia

Normal é > 1A

Medida no terra do transformador

Variação no brilho

Mínimo e Máximo

Manchas?

Sol no raio-X

Ejeta bolhas de partículas ionizadas

Bolhas com bilhões de toneladas

Viajam a 1 milhão km/hrLevam 3 a 4 d para chegar na Terra

Ejeção coronal de massa

Algumas bolhas vêm emnossa direção

Magnetosfera da Terra

Anomalia Geomagnética do Atlântico Sul

Vermelho: prótons de 30 keV

Bolha chega na Terra

http://www.sec.noaa.gov

Data Hora (UT) Índice Kp

20 nov 2003 12 hr 9

4 out 2003 12 hr 7

30 out 2003 0 hr 9

30 out 2003 11 hr 9

24 out 2003 14 hr 7

15 out 2003 9 hr 7

17 set 2003 11 hr 7

23 ago 2003 9 hr 7

18 ago 2003 9 hr 7

6 ago 2003 9 hr 7

12 jul 2003 6 hr 7

18 jun 2003 9 hr 7

29 maio 2003 22 hr 8

Últimas tempestades

Fluxo 100 000 maior!Equivalente a 10-100 raio-X

Índice planetário Kp

Média das perturbações (máximo-mínimo) ao campo magnético terrestre de 13 estações subaurorais, após subtrair a média.

O nome Kp vem de "planetarische Kennziffer" ( = índice planetário). Um K=9 varia de acordo com a estação, de 500 nT a 1500 nT.

International Association for Geomagnetism and Aeronomy, IAGA

Mudanças no Hp=campo paralelo ao da Terra, perpendicular ao da órbita do satélite. O campo médio da Terra é 4000 nT

4 Nov 2003

30 0ut 2003

Out-nov 2003

Julho 2000

Exposição à radiação

Sol mínimo: 3,6 mSy/anoRecomendado: 1 mSy/ano

Radiação ultravioleta ao meio-dia

Exposição à radiação UV

TipoComprimento de

ondaComentário

UVC 200-280 nm camada de ozônio filtra

UVB 280-320 nmcausa formação de melanina

UVA 320-400 nm oxida a melanina, dando cor

visível

400-780 nm  

Ozônio

Ozônio em 2001

Buraco de agosto a novembro

Em 2000

Absorção pela atmosfera

Exposição eritêmica

http://jwocky.gsfc.nasa.gov/ery_uv/ery_uv1.html