L12 - PE for HVDC Flashcards
What are power electronics?
The application of solid-state electronics to control the conversion or transmission of electric power
Vo = V̂ * cos(w*t)
V̂ = amplitude w = frequency
What to power converters do?
Control the grid, electrical machines etc.
More effectively and increase efficiency
What is a semiconductor material?
A material whose conductivity can be controlled by applying an electric field
Isolator - open switch
Conductor - closed switch
Regulated by adding impurities during manufacturing process doping.
What is an ideal power switch?
A switch with instant turn on/off
Made of a semiconductor material
What determines the switching patterns of the gate?
By the application where the switch is used
Name 5 semiconductor types
- Diode
- Diode rectifier
- Thyristor
- MOSFET
- IGBT
What are the qualities of the different power semiconductors?
Thyristor: Very low frequency, Very high Voltage/Current
IGBT: Low frequency, High voltage and current
MOSFET: High frequency, low voltage and current
Difference between SiC and Si IGBT
SiC can:
- withstand higher voltages
- Lower conduction losses
- Much lower switching losses
- Can handle higher operating temperatures (> 250 C)
What are shunt capacitors and what are their qualities?
- Capacitors connected in parallel to the AC transmission lines
- Locally boosting reactive power increasing the efficiency of the grid and boosting the voltage of that mode
- Low flexibility into tuning the required reactive power using discrete number of capacitors
Name three types of capacitors
Ceramic - low power, more expensive Film - Electric drives, harmonic filters Electrolytic - Inexpensive, low frequency
Advantages and disadvantages with tidal power
+ Fully predictable tidal stream and rubustness against weather volatility
- Very costly and large infrastructure
