Flexible-AC-Transmission-System
The concept of Flexible AC Transmission System ( in German: Flexible AC Transmission System), abbreviated FACTS, in the electric power industry has several control systems, which are used in power supply systems for the targeted control of power flows. Thereby come to be critical components of the power electronics, similar to the high-voltage direct current transmission (HVDC), are used. The power electronics will not be used for power transmission by means of dc; rather, it is intended to affect power flows in three-phase AC systems without rotating equipment.
The term is defined by the IEEE as a static power electronics, which in one or more alternating-voltage networks specifically electrical parameter for transmitting power influence, so as to exploit the transmission capacity can be optimized.
General
The control of power flows can be performed in meshed AC systems by changing the reactive and active power by means of capacitor banks or compensation coils to the tertiary windings of power transformers. This corresponds to a parallel compensation (English Shunt Compensation). Furthermore, the power flow may be changed by means of a series compensation, for example, by phase shifting transformer. Another possibility is restricted directly in the power plant in the modification of the angular displacement of the usual synchronous generators for power generation. There are also possibilities of varying voltages within limits by step switch in the power transformers.
FACTS includes methods for load flow control and to stabilize the grid in electrical power networks by means of power electronics, the electronics is used directly in a range of power flow and not only serves to control and regulation technology. In this case, the power electronics has the advantage of being able to respond almost wear-free and inertia to changes. A disadvantage is the high technological effort involved and the higher costs involved. To the field of Flexible AC Transmission Systems include:
- Static Synchronous Compensator ( STATCOM ), an electronic unit for parallel compensation of kapazitivier or inductive reactive power.
- Unified Power Flow Controller ( UPFC ), the Unified Power Flow Controller, provides the functionally most powerful electronic system dar. The UPFC can be used both for parallel and series compensation of capacitive or inductive reactive power and for the targeted control of active power flows used in high- voltage power lines. Furthermore, thus changing the natural capacity of overhead lines and unbalanced loads are balanced in certain areas.