Power Semiconductor Devices for HVDC and FACTS Systems

Power Semiconductor Devices for HVDC and FACTS Systems

• Power semiconductor devices are key components in power converters for High Voltage Direct Current Transmission (HVDC) and Flexible Alternating Current Transmission Systems (FACTS).

History of Power Semiconductors

• 1940-1945: First steps toward modern power electronics with the appearance of ignitron and excitron, and development of silicon and germanium devices.
• 1950: W.B. Shockley initiates the idea for a thyristor (THY) with a p-n hook-collector.
• 1952: Ebers analyzes the operation mechanism of THY.
• 1956: J.L. Moll further investigates the switching mechanism of THY.
• 1957: First THY, known as silicon-controlled rectifier (SCR), is produced by General Electric Company.
• 1960: Gate turn-off thyristor (GTO) is developed.
• 1968: Insulated gate controlled thyristor (IGCT) is developed.
• 1975: Metal oxide semiconductor field effect transistor (MOSFET) is developed.
• 1980s: Isolated gate bipolar transistor (IGBT) is developed, combining the advantages of bipolar transistors and MOSFETs.

Classification of Power Semiconductor Devices

• Not-Controllable Devices: Power diodes, which do not need control, with examples of applications in rectification, clamping, and overvoltage protection.

Thyristor (THY)

• Structure: Four-layer p-n-p-n material with three p-n junctions.
• Operation: THY can be turned on by applying a short positive current pulse at the gate, and remains in the on-state until the next current zero crossing.
• Features: High current densities possible (in the range of kA), latched operation, and controllability limited to one switching per half-cycle.
• Applications: HVDC, with highly reliable and robust operation, used in series-connected THY valves.

Light-Triggered Thyristor (LTT)

• Triggered by optical fibers transmitting the gate signal in the form of infrared light pulse directly to a light-sensitive region of the silicon around the gate.
• Features: Improved noise rejection, simplified circuit, and reduced complexity, but with higher cost and limited manufacturers.

Gate Turn-Off Thyristor (GTO)

• Structure: Similar to THY, but with turn-off controllability.
• Operation: GTO turns on with a short positive current pulse, and turns off with a large negative current pulse.
• Features: Long turn-off times, limiting applications to only 1 kHz switching frequency, and requiring external snubber circuits.
• Applications: Being replaced by IGCTs in more demanding applications.

Integrated Gate-Commutated Thyristor (IGCT)

• Structure: Press-pack device with improved characteristics.
• Operation: IGCT turns on with a short positive current pulse, and turns off with a large negative current pulse.
• Features: Reduced forward voltage and shorter commutation times compared to GTO.
• Applications: Used in HVDC and FACTS systems, with improved performance and reliability.

Power Semiconductor Devices for HVDC and FACTS Systems

• Power semiconductor devices are key components in power converters for High Voltage Direct Current Transmission (HVDC) and Flexible Alternating Current Transmission Systems (FACTS).

History of Power Semiconductors

• 1940-1945: First steps toward modern power electronics with the appearance of ignitron and excitron, and development of silicon and germanium devices.
• 1950: W.B. Shockley initiates the idea for a thyristor (THY) with a p-n hook-collector.
• 1952: Ebers analyzes the operation mechanism of THY.
• 1956: J.L. Moll further investigates the switching mechanism of THY.
• 1957: First THY, known as silicon-controlled rectifier (SCR), is produced by General Electric Company.
• 1960: Gate turn-off thyristor (GTO) is developed.
• 1968: Insulated gate controlled thyristor (IGCT) is developed.
• 1975: Metal oxide semiconductor field effect transistor (MOSFET) is developed.
• 1980s: Isolated gate bipolar transistor (IGBT) is developed, combining the advantages of bipolar transistors and MOSFETs.

Classification of Power Semiconductor Devices

• Not-Controllable Devices: Power diodes, which do not need control, with examples of applications in rectification, clamping, and overvoltage protection.

Thyristor (THY)

• Structure: Four-layer p-n-p-n material with three p-n junctions.
• Operation: THY can be turned on by applying a short positive current pulse at the gate, and remains in the on-state until the next current zero crossing.
• Features: High current densities possible (in the range of kA), latched operation, and controllability limited to one switching per half-cycle.
• Applications: HVDC, with highly reliable and robust operation, used in series-connected THY valves.

Light-Triggered Thyristor (LTT)

• Triggered by optical fibers transmitting the gate signal in the form of infrared light pulse directly to a light-sensitive region of the silicon around the gate.
• Features: Improved noise rejection, simplified circuit, and reduced complexity, but with higher cost and limited manufacturers.

Gate Turn-Off Thyristor (GTO)

• Structure: Similar to THY, but with turn-off controllability.
• Operation: GTO turns on with a short positive current pulse, and turns off with a large negative current pulse.
• Features: Long turn-off times, limiting applications to only 1 kHz switching frequency, and requiring external snubber circuits.
• Applications: Being replaced by IGCTs in more demanding applications.

Integrated Gate-Commutated Thyristor (IGCT)

• Structure: Press-pack device with improved characteristics.
• Operation: IGCT turns on with a short positive current pulse, and turns off with a large negative current pulse.
• Features: Reduced forward voltage and shorter commutation times compared to GTO.
• Applications: Used in HVDC and FACTS systems, with improved performance and reliability.

This chapter covers the history and development of power semiconductor devices, including thyristors, ignitrons, and excitrons, and their applications in HVDC and FACTS systems.