How does a "converter transformer" handle DC voltage control?
1 Answer
A "converter transformer" is a type of transformer that is specifically designed for use in high-voltage direct current (HVDC) systems. HVDC systems are used to transmit electric power over long distances, often across regions or even countries, using direct current (DC) rather than alternating current (AC). Converter transformers play a crucial role in these systems by facilitating the conversion between AC and DC voltage levels.
In an HVDC system, the converter transformers are used at both ends of the transmission line, typically referred to as the "rectifier" end and the "inverter" end. The rectifier end converts AC voltage from the power grid into DC voltage, and the inverter end converts the DC voltage back into AC voltage for distribution. Here's a simplified explanation of how a converter transformer handles DC voltage control:
Rectifier End:
AC-to-DC Conversion: At the rectifier end, the converter transformer steps up the AC voltage from the power grid to a high level. This high-voltage AC is then fed into a set of rectifiers (typically composed of semiconductor devices like thyristors) that convert the AC voltage to DC voltage.
Voltage Control: The DC voltage level can be controlled by adjusting the firing angle of the rectifier devices. This angle determines when the rectifiers turn on and off during each AC cycle, thus controlling the amount of AC voltage that is converted to DC voltage. By altering the firing angle, the average DC voltage can be controlled, allowing for regulation of the transmitted power and voltage.
Inverter End:
DC-to-AC Conversion: At the inverter end, the converter transformer receives the high-voltage DC from the transmission line. This DC voltage is then fed into a set of inverters, which are also made up of semiconductor devices like thyristors or insulated gate bipolar transistors (IGBTs). The inverters convert the DC voltage back into AC voltage.
Voltage Control: Similar to the rectifier end, the inverter end can also control the AC voltage level by adjusting the firing angle or switching frequency of the inverter devices. This allows for the regulation of the output AC voltage and frequency.
Overall, the control of the DC voltage in an HVDC system is achieved through careful management of the rectifier and inverter devices, which are controlled by sophisticated control systems that monitor the grid conditions and adjust the converter operation accordingly. The converter transformer itself serves as a key component in enabling this AC-DC-AC voltage conversion process in HVDC systems.
In an HVDC system, the converter transformers are used at both ends of the transmission line, typically referred to as the "rectifier" end and the "inverter" end. The rectifier end converts AC voltage from the power grid into DC voltage, and the inverter end converts the DC voltage back into AC voltage for distribution. Here's a simplified explanation of how a converter transformer handles DC voltage control:
Rectifier End:
AC-to-DC Conversion: At the rectifier end, the converter transformer steps up the AC voltage from the power grid to a high level. This high-voltage AC is then fed into a set of rectifiers (typically composed of semiconductor devices like thyristors) that convert the AC voltage to DC voltage.
Voltage Control: The DC voltage level can be controlled by adjusting the firing angle of the rectifier devices. This angle determines when the rectifiers turn on and off during each AC cycle, thus controlling the amount of AC voltage that is converted to DC voltage. By altering the firing angle, the average DC voltage can be controlled, allowing for regulation of the transmitted power and voltage.
Inverter End:
DC-to-AC Conversion: At the inverter end, the converter transformer receives the high-voltage DC from the transmission line. This DC voltage is then fed into a set of inverters, which are also made up of semiconductor devices like thyristors or insulated gate bipolar transistors (IGBTs). The inverters convert the DC voltage back into AC voltage.
Voltage Control: Similar to the rectifier end, the inverter end can also control the AC voltage level by adjusting the firing angle or switching frequency of the inverter devices. This allows for the regulation of the output AC voltage and frequency.
Overall, the control of the DC voltage in an HVDC system is achieved through careful management of the rectifier and inverter devices, which are controlled by sophisticated control systems that monitor the grid conditions and adjust the converter operation accordingly. The converter transformer itself serves as a key component in enabling this AC-DC-AC voltage conversion process in HVDC systems.