31-01-2015, 01:40 PM
about ten difference between upfc and upqc
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ten difference between upfc and upqc
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about ten difference between upfc and upqc
25-03-2017, 03:20 PM
A unified power flow controller (or UPFC) is an electrical device for providing fast acting reactive power compensation in high voltage electricity transmission networks. It uses a pair of controllable three-phase jumpers to produce current that is injected into a transmission line using a serial transformer. The controller can control active and reactive power flows on a transmission line. The UPFC uses solid-state devices, which provide functional flexibility, generally not achievable by conventional thyristor controlled systems. The UPFC is a combination of a static static compensator (STATCOM) and a static synchronous series compensator (SSSC) coupled through a common DC link. The main advantage of the UPFC is the control of active and reactive power flows in the transmission line. If there is any disturbance or fault on 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 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 as the stability control to suppress oscillations of the power system that improve the transient stability of the power system.
Power electronics are playing an important role in the transmission and use of electric power because of their ability to process electrical energy in the most efficient and cost-effective way. However, the nonlinear characteristics of electronic power devices give rise to two important limitations; They generate harmonics and draw the delayed utility current. In recent years, UPQC is an all-in-one device for active energy conditioning to compensate for both harmonics and reactive power. UPQC is an advanced version of the Unified Power Flow Controller (UPFC). The performance of UPQC depends mainly on the speed and precision with which the compensation signals are derived. The UPQC mitigates harmonics and provides reactive power to the grid of power systems to improve the power factor close to unity. The penetration of wind energy has increased dramatically in recent years, so it has been necessary to address the problems associated with maintaining a stable electrical power system containing different sources of energy including hydroelectric, thermal, coal, nuclear, Wind and solar. In the past, total installed wind power capacity was a small fraction of the electrical system and the continued connection of the wind farm to the grid was not a major concern. With an increasing share of wind energy sources, the continuous connection of wind farms to the system has played an increasingly important role in allowing uninterrupted power supply of the load, even in the event of minor disturbances.
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