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Two types of HVDC converters are used for conversion of AC to DC and vice versa. The first type is the line commutated converter (LCC). This converter valves in the LCC systems requires that they are connected to an AC power source for their operation. The valves can be turned on but not turned off by the application of a voltage injecting currents into the gate of the device. This type of system consumes a significant amount of reactive power for its operation. Also, the polarity of the current flow is always the same, so a power flow direction change requires a change of the DC voltage polarity. The second type is voltage sourced converters that include valves that can be turned on as well as tuned off by means of gate control actions. A VSC converter can generate its own reactive power support. That is, it can operate with a power factor of one irrespective of the amount of active power that flows through the converter. A VSC converter can change its current flow polarity and therefore does not require a change of the voltage polarity to accomplish a change of the power flow direction. Although in many respects, the power flow control as seen from the AC connection points is in many respects similar, the control systems for the two types of converters are as described here quite dissimilar. For hybrid HVDC transmission systems that contain both LCC and VSC converters, the control and protections systems for the different types of converters have to be built to accommodate both types of converters.

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Control and Protection of LCC and VSC HVDC Converter Stations

  • 工具书词条

  • 发表日期：

    2025年

查看全文
  • Hans Björklund,
  • Rodrigo Alvarez,
  • Fredrik W. Jansson,
  • Stig Nilsson,
  • Benedikt Regnier,
  • Hani Saad,
  • Lin Zheng,
  • Magnus Öhrström,
  • Xiaoyu Zhang

摘要

Two types of HVDC converters are used for conversion of AC to DC and vice versa. The first type is the line commutated converter (LCC). This converter valves in the LCC systems requires that they are connected to an AC power source for their operation. The valves can be turned on but not turned off by the application of a voltage injecting currents into the gate of the device. This type of system consumes a significant amount of reactive power for its operation. Also, the polarity of the current flow is always the same, so a power flow direction change requires a change of the DC voltage polarity. The second type is voltage sourced converters that include valves that can be turned on as well as tuned off by means of gate control actions. A VSC converter can generate its own reactive power support. That is, it can operate with a power factor of one irrespective of the amount of active power that flows through the converter. A VSC converter can change its current flow polarity and therefore does not require a change of the voltage polarity to accomplish a change of the power flow direction. Although in many respects, the power flow control as seen from the AC connection points is in many respects similar, the control systems for the two types of converters are as described here quite dissimilar. For hybrid HVDC transmission systems that contain both LCC and VSC converters, the control and protections systems for the different types of converters have to be built to accommodate both types of converters.