What is a 12 pulse converter?
A 12-pulse rectifier uses two 6-pulse rectifiers in parallel (12 diodes) to feed a common DC bus. A transformer with one primary and two secondary windings creates a 30 degree phase shift between the two current waveforms, which eliminates the 5th and 7th harmonics and reduces current THD to between 10 and 15 percent.
What is pulse number in HVDC?
Pulse number is defined as the number of pulses in the dc output voltage within one time period of the ac source voltage. In high-power applications, ac–dc converters based on the concept of multipulse, namely, 12, 18, 24, 30, 36, 48 pulses are used to reduce the harmonics in ac supply currents.
What is the difference between 6-pulse and 12 pulse rectifier?
2、12-pulse rectifier principle: 12 pulses means that on the basis of the original 6-pulse rectification, a set of 6-pulse rectifiers is added at the input end and after adding the phase-shifting transformer, so that the DC bus current is completed by 12 thyristors, so it is also called 12-pulse rectification.
What is a pulse converter?
The pulse converter converts and divides pulse signals from third party devices into pulse signals that can be processed by controllers from Technische Alternative. The signals can come from a potential-free contact (e.g. Reed contact) or the open collector output of an NPN transistor.
Why more than six pulse is used in HVDC converters?
HVDC systems based on voltage-source converters normally use the six-pulse connection because the converter produces much less harmonic distortion than a comparable LCC and the twelve-pulse connection is unnecessary. This simplifies the construction of the converter transformer.
What is a 6-pulse converter?
It is called a 6-pulse design because it draws current in six distinct pulses from the AC system. It uses six rectifier devices to form a three-phase full wave bridge. This is the procedure for changing DC voltage into AC voltage in a converter station.
Which converter is used in HVDC?
An HVDC converter converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice versa. HVDC is used as an alternative to AC for transmitting electrical energy over long distances or between AC power systems of different frequencies.
Which converter is used in HVDC transmission?
In HVDC transmission a 12-pulse bridge converter is used. The converter obtains by connecting two or 6-pulse bridge in series.
What is a 6 pulse converter?
What is a 3 pulse converter?
Consider a three-phase 3-pulse converter, where each of the thyristor is in conduction mode during the third of the supply cycle. The earliest time a thyristor is triggered into conduction is at 30° in reference to the phase voltage. Its operation is explained using three thyristors and three diodes.
What is meant by 2 pulse converter?
What is meant by 2 pulse converter? Two pulse converters is defined as two triggering pulses or two sets of triggering pulses are to be generated during every cycle of the supply to trigger the various SCRs.
What happened with the DC voltage across a 6 pulse bridge?
Commutation failure in six pulse bridge is characterized by (i) Significant reduction of AC phases current amplitudes whereas current on the DC side is subject to increase. (ii) Significant increase of AC phases current amplitudes whereas current on the DC side is subject to reduced.
What is converter transformer in HVDC?
Spare converter transformer in the switchyard of an HVDC station. The converter transformers are designed to withstand dc voltage stresses and increased eddy current losses due to harmonic currents. One problem that can arise is due to the dc magnetization of the core due to unsymmetrical firing of valves.