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The task of additional reactive power compensation (also known as voltage compensation) is assigned to compensating devices: [7] passive (either permanently connected or switched) sinks of reactive power (e.g., shunt reactors that are similar to transformers in construction, with a single winding and iron core [9]).
A unified power flow controller (UPFC) is an electrical 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. [ 1 ]
Power electronics are combined in series with a reactor to form a Voltage-Sourced Converter (VSC), which when connected to an AC system forms a STATCOM. [15] A VSC use the same principal of power flow on a transmission line; measuring the system voltage its connected to and varying the voltage of the power electronics to cause reactive power ...
The current in the TCR is varied from maximum (determined by the connection voltage and the inductance of the reactor) to almost zero by varying the "Firing Delay Angle", α. α is defined as the delay angle from the point at which the voltage becomes positive to the point at which the thyristor valve is turned on and current starts to flow.
Unlike the TCR, the TSC is only ever operated fully on or fully off. An attempt to operate a TSC in ‘’phase control’’ would result in the generation of very large amplitude resonant currents, leading to overheating of the capacitor bank and thyristor valve, and harmonic distortion in the AC system to which the SVC is connected.
In power engineering, the power-flow study, or load-flow study, is a numerical analysis of the flow of electric power in an interconnected system. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various aspects of AC power parameters, such as Voltage, voltage angles, real power and reactive power.
Reactive power does not do any work, so it is represented as the imaginary axis of the vector diagram. Active power does do work, so it is the real axis. The unit for power is the watt (symbol: W). Apparent power is often expressed in volt-amperes (VA) since it is the product of RMS voltage and RMS current. The unit for reactive power is var ...
The term power system control describes actions taken in response to unplanned disturbances (e.g., changes in demand or equipment failures) in order to provide reliable electric supply of acceptable quality. [3] The corresponding engineering branch is called Power System Operations and Control.