What is line-commutated?
Line-commutated converters (LCCs) are the conventional, mature and well-established technology used to convert electric power from AC to DC or vice versa. In a current source converter (CSC), the DC current is kept constant with a small ripple using a large inductor.
What is line rectifier?
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it “straightens” the direction of current.
What is a line commutation circuit?
Natural or Line commutation is a Class-F SCR commutation technique in which, a thyristor is turned off due to natural current zero and voltage reversal after every half cycle.
What is the significance of line-commutated converter?
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 commutation is used in Rectifier?
The type of commutation used in controlled rectifier circuits is referred to AC line commutation or Natural commutation or AC phase commutation. When the input ac supply voltage reverses and becomes negative during the negative half cycle, the thyristor becomes reverse biased and hence turns off.
Why it is called line commutated inverter?
The thyristors in the converter circuit are commutated with the help of the supply voltage in the rectifying mode of operation and are known as “Line commutated converter”. Since the frequency of the harmonic voltage is higher smaller load inductance leads to continuous conduction.
Which commutation method is faster?
It has been found that with simple modification of the Input Current Filtering circuit and Diode Clamp circuit; the Stepless current commutation can be achieved giving the fastest, safe and simplest commutation technique without any voltage & current sensors and complex commutation steps.
What is commutation and its types?
The process used for turning off a thyristor is called commutation. By the commutation process, the thyristor operating mode is changed from forward conducting mode to forward blocking mode. The commutation techniques of thyristors are classified into two types: Natural Commutation. Forced Commutation.
What is pulse rectifier?
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 are the components in a simple converter?
AC Switchyard. The AC system connects to a HVDC converter station via a “converter bus”, which is simply the AC busbar to which the converter is connected.