HVDC Concepts: section 5 - 6-pulse inverter

In a similar way to the 6-wave rectifier we discussed earlier, a 6-pulse inverter converts DC to AC. You can see this diagram now shows the three sets of full-wave inverters joined in parallel. We will now run through each pulse in turn. With pulse 1, you can see red phase on the positive side pulse on the increasing side of the sine wave. Yellow phase is on a negative pulse on the decreasing side of the sine wave. Blue phase is not conducting. With pulse 2, you can see blue phase on a negative pulse on the increasing side of the sine wave. Red phase is on a positive pulse on the decreasing side of the sine wave. Yellow phase is not conducting. With pulse 3, you can see yellow phase on a positive pulse on the increasing side of the sine wave. Blue phase is on a negative pulse on the decreasing side of the sine wave. Red phase is not conducting. With pulse 4, you can see yellow phase on a positive pulse on the decreasing side of the sine wave. Red phase is on a negative pulse on the increasing side of the sine wave. Blue phase is not conducting. With pulse 5, you can see red phase on a negative pulse on the decreasing side of the sine wave. Blue phase is on a positive pulse on the increasing side of the sine wave. Yellow phase is not conducting. And finally, with pulse 6 you can see blue phase on a positive pulse on the decreasing side of the sine wave. Yellow phase is on the negative pulse on the increasing side of the sine wave. And red phase is not conducting. You can see the pulses all coming together in sync to invert. Transpower uses solid state devices called thyristors as rectifiers and inverters for the conversion of high-voltage DC to high-voltage AC, and back again. The thyristors operate in 12-pulse mode which gives a smoother and more efficient conversion with less harmonics. The HVDC converter station being used by Transpower consists of a total of 792 individual thyristors.

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Keywords: system operator, electricity, High-voltage Direct Current, Energy, Transpower New Zealand Limited (Organization), transpower, New Zealand (Country), hvdc, training

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Length: 2min 30sec (150 seconds)

Published: Wed Oct 09 2013