HVDC Quiz-2

In HVDC converters, the thyristor are connected in series

• To provide the required current rating, and they are turned on at the same instant.

• To provide the required current rating, and they are turned on at different instants.

• To provide the required voltage rating, and they are turned on at the same instant.

• To provide the required voltage rating, and they are turned on at different instants.

Asynchronous tie line is a

• AC transmission line

• DC transmission line

• either 1 or 2

• none of the above

Which type of connection on the secondary side of transformer-1 and transformer-II is used to obtain phase shift of 30 degrees in 12 pulses Converter?

• Delta-Star

• Star-Star

• Delta-Delta

• Star-Delta

The output voltage equation of 12 pulse converter is

• Vd = 0.5Vd0 Cosα

• Vd = 2Vd0 Cosα

• Vd = 3Vd0 Cosα

• Vd = Vd0 Cosα

If the firing angle becomes negative, then the rectifier begins to work as

• A rectifier

• A chopper

• An inverter

• A regulator

With increase in delay angle α

• p.f. is reduced

• DC voltage decreases

• both (a) and (b)

• kVAR requirement decreases

For inversion or inverter operation

• α ≤ 90°

• α > 90°

• 90° < α < 180°

• 180° < α < 270°

For stable operation of DC systems

• CC and CEA control is adopted

• α control, CC and CEA is adopted

• only CEA control is adopted

• only CC control is adopted

Characteristic of a converter is the relation between

• AC voltage and Id

• DC power and Id

• DC output voltage and Id

• α and Id

HVDC system prefer 12 pulse converter because

• High ripple and high harmonics

• No ripple and no harmonics

• Less ripple and less harmonics

• None of the above