1 Interconnected Operation Of Large Power Systems

1 Interconnected operation of large power systems

1.3

Interconnected systems world wide

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Interconnected systems in North America

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Interconnected systems in Japan

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Interconnected systems in China

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1.3.1

1.3 Interconnected systems world-wide

1.3.2

Interconnected systems in North America •

In the US and Canada more than 3.000 companies are engaged in generation, transmission and distribution of electrical energy. These are mostly private companies but there are also large utilities in public ownership (e.g. Tennessee Valley Authority, Bonneville Power Administration).

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The network in North America consists of 4 synchronous systems interconnected with Back-Back HVDC ties and HVDC lines:

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Eastern Interconnection: Eastern part of the US and 4 provinces of Canada (Installed Capacity approx. 610 GW)

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Western Interconnection: Western part of the US and 2 provinces of Western Canada and the Northern part of Baja (Mexico) (Installed Capacity approx. 160 GW)

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Texas system:

State of Texas (Installed Capacity approx. 62 GW)

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Quebec system:

Province of Quebec (Installed Capacity approx. 30 GW)

The voltage levels range from 230 kV, 345 kV, 500 kV, 735 kV, 765 kV up to 1000 kV DC.

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1.3 Interconnected systems world-wide

Interconnected systems in North America

1.3.3

Quebec System

Eastern Interconnection

Western Interconnection Texas System

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1.3 Interconnected systems world-wide

Break-even distance for HVDC

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1.3.3 /1

1.3 Interconnected systems world-wide

1.3.4

Interconnected system in Japan •

The interconnected system in Japan is composed of 9 electric power companies.

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The 3 companies Hokkaido, Tohoku and Tokyo in the eastern region operate their networks with the frequency of 50 Hz, the 6 companies in the west with a frequency of 60 Hz. Between the two regions with different frequencies there are two Back-Back HVDC couplings with the capacities of 600 MW and 300 MW. The island Hokkaido is interconnected with the main island Honshu by a HVDC cable (± 250 kV) with a capacity of 600 MW.

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Installed capacity (2000): 190 GW - 115 GW (60%) in coal, oil, gas units - 42 GW (22%) in nuclear units - 33 GW (18%) in hydro and other units

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Total demand (2000) 950 TWh

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1.3 Interconnected systems world-wide

1.3.5

Interconnected system in Japan •

In Japan 44 nuclear power units were in operation in 1992. 10 nuclear power plants with a total capacity of 12 GW are under construction or in the planning phase.

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Until 1992 the highest voltage level for AC transmission was 500 kV. Three 1000 kV AC lines located in the Tokyo area are under construction. Operation with 1000 kV will start early in the 21st century.

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Synchronous condensors and SVCs are widely used to improve voltage stability and to suppress voltage fluctuations near DC converter stations.

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In selected power stations PSSs are installed to suppress low frequency power oscillations.

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1.3.6

1.3 Interconnected systems world-wide

Interconnected system in Japan

Hokkaido [3%]

[%]: kWh demand in 2000 (total 950 TWh)

HVDC Cable 600 MW

Hokuriku [3%]

HVDC Back-Back 600 MW

Kyushu [8%]

Chugoku [7%]

Shikoku [3%]

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Kansai [19%]

Chubu [15%]

Tokyo [34%] HVDC Back-Back 300 MW

60 Hz

50 Hz

Tohoku [8%]

1.3 Interconnected systems world-wide

1.3.7

Interconnected systems in China • 82 % of coal reserves are concentrated in the north • 67 % of hydro resources are located in the southwest of China • Majority of electricity consumption located in the coastal regions of the east and south and the central regions • 6 regional power systems interconnected by 500 kV AC-lines and ± 500 kV DC lines; Xinjiang region and Xizang region operated as electrical islands • Three Gorges; famous hydro power project in the southwest of China with 26 generating units 700 MW each

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1.3 Interconnected systems world-wide

1.3.8

China: Interconnection of six regional systems (2005) North East China North West China

North China

Central China

East China

Three Gorges South China

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HVAC HVDC

1.3 Interconnected systems world-wide

1.3.9

The electric power system in China (2004) The installed generation capacity was in 2004: -

326 GW

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7 GW

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108 GW

(74 %) in coal, oil or gas units (1.6 %) in nuclear power plants (24 %) in hydro generation or others

The total generation was in 2004: -

1640 TWh

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15 TWh

-

525 TWh

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441 GW

(75%)

2187 TWh in coal, oil or gas units

(0.7%) in nuclear power plants (24%)

in hydro generation or others