A unified power flow controller (UPFC) is an

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

device for providing fast-acting reactive power compensation on high-voltage electricity transmission networks. It uses a pair of three-phase controllable bridges to produce current that is injected into a transmission line using a series transformer. The controller can control active and reactive power flows in a transmission line. Unified Power Flow Controller (UPFC), as a representative of the third generation of FACTS devices, is by far the most comprehensive FACTS device, in power system steady-state it can implement power flow regulation, reasonably controlling line active power and reactive power, improving the transmission capacity of power system, and in power system transient state it can realize fast-acting reactive power compensation, dynamically supporting the voltage at the access point and improving system voltage stability, moreover, it can improve the damping of the system and power angle stability. The UPFC uses solid state devices, which provide functional flexibility, generally not attainable by conventional

thyristor A thyristor (, from a combination of Greek language ''θύρα'', meaning "door" or "valve", and ''transistor'' ) is a solid-state semiconductor device which can be thought of as being a highly robust and switchable diode, allowing the passage ...

controlled systems. The UPFC is a combination of a static synchronous compensator ( STATCOM) and a static synchronous series compensator ( SSSC) coupled via a common DC voltage link. The main advantage of the UPFC is to control the active and reactive power flows in the transmission line. If there are any disturbances or faults in the source side, the UPFC will not work. The UPFC operates only under balanced sine wave source. The controllable parameters of the UPFC are reactance in the line, phase angle and voltage. The UPFC concept was described in 1995 by L. Gyugyi of Westinghouse. The UPFC allows a secondary but important function such as stability control to suppress power system oscillations improving the transient stability of power system.

Power flow controller for direct current

A counterpart for unified power flow controller that can be used in

direct current Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow throug ...

systems was proposed for use in high-voltage direct current grids and for low-voltage direct current

microgrid A microgrid is a local electrical grid with defined electrical boundaries, acting as a single and controllable entity. It is able to operate in grid-connected and off-grid modes.

s. It uses a high-frequency isolated

DC-to-DC converter A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of Electric power conversion, electric power converter. Power levels range from ...

cascaded with a controllable full-bridge inverter that creates a small bipolar voltage in series with the line. The controller can control the power and compensate for accumulated voltage drop in a distribution line. The main advantage of the solution is the ability to control the bulk power flow in the line while actively processing only a small fraction of the bulk power. The partial power processing leads to increased system efficiency and use of derated components. The use of derated components results in small and cost-efficient designs.

References

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External links

NR Electric PCS-8200 UFPC Solution
Electricity

Power flow controller for direct current

See also

References

External links