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Long distance HVDC lines carrying hydroelectricity from Canada's Nelson River to this converter station where it is converted to AC for use in southern Manitoba's grid. A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. [1]
DC to AC conversion is useful for many fields, including power conditioning, harmonic compensation, motor drives, renewable energy grid integration, and spacecraft solar power systems. In power systems it is often desired to eliminate harmonic content found in line currents. VSIs can be used as active power filters to provide this compensation.
A diagram of an electric power system. The transmission system is in blue. Most North American transmission lines are high-voltage three-phase AC, although single phase AC is sometimes used in railway electrification systems. DC technology is used for greater efficiency over longer distances, typically hundreds of miles.
Until then, electricity was usually generated where it was used. The first power-distribution systems installed in European and US cities were used to supply lighting: arc lighting running on very-high-voltage (around 3,000 V) alternating current (AC) or direct current (DC), and incandescent lighting running on low-voltage (100 V) direct ...
An electrical load is an electrical component or portion of a circuit that consumes (active) electric power, [1] [2] such as electrical appliances and lights inside the home. The term may also refer to the power consumed by a circuit. This is opposed to a power supply source, such as a battery or generator, which provides power. [2]
The majority of the load in a typical AC power system is inductive; the current lags behind the voltage. Since the voltage and current are out-of-phase, this leads to the emergence of an "imaginary" form of power known as reactive power. Reactive power does no measurable work but is transmitted back and forth between the reactive power source ...
In power electronics applications, since the switching element is either fully on or fully off, its losses are low and the circuit can provide high efficiency. However, the current supplied to the load is discontinuous and may require smoothing or a high switching frequency to avoid undesirable effects.
In a battery electric vehicle, there are usually two separate DC systems. The "low voltage" DC system typically operates at 12V, and serves the same purpose as in an internal combustion engine vehicle. [10] The "high voltage" system operates at 300-400V (depending on the vehicle), and provides the power for the traction motors. [11]