Why Southern China Broke Up Its Power Grid

An abundance of high-voltage DC makes big AC grids unstable

4 min read
Photo: China Southern Power Grid
Eastward-Flowing Power: Hydropower projects feed China’s eastern megacities using HVDC technology.
Photo: China Southern Power Grid

Throughout the 20th century,utilities merged transmission systems with neighboring grids, creating ever-larger AC electricity grids. Some, such as Europe’s and North ­America’s, now approach continental scale. But a recent move in China to break up an AC grid suggests that growing use of DC transmission technology may turn back the clock.

Grid operators have synchronized their AC power grids with neighboring systems to take advantage of electricity trading opportunities and mutual support. When a storm knocks out a high-voltage line or power station, for example, larger AC grids offer the resources and electrical inertia to absorb the loss.

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This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

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