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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 ]
Heavily loaded lines consumed reactive power due to the line's inductance, and as transmission voltage increased throughout the 20th century, the higher voltage supplied capacitive reactive power. As operating a transmission line only at it surge impedance loading (SIL) was not feasible, [2] other means to manage the reactive power was needed.
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.
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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.
This feature can provide controllable voltage compensation. [2] In addition, SSSC is able to reverse the power flow by injecting a sufficiently large series reactive compensating voltage. [2] The SSSC consists of a voltage source converter (VSC) connected in series with the transmission line through a transformer.
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 ...