Voltage Limits and Currents on Power Systems Essay example

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The various nonlinear loads like Adjustable Speed Drives (ASD’s), bulk rectifiers, furnaces, computer supplies, etc. draw non sinusoidal currents containing harmonics from the supply which in turn causes voltage harmonics. Current harmonic causes increased power system losses, excessive heating in rotating machinery, interference with nearby communication circuits and control circuits, etc. It has become a vital importance to maintain the sinusoidal nature of voltage and currents in the power system. Various international agencies like IEEE and IEC have issued standards, which put limits on various current and voltage harmonics. The limits for various current and voltage harmonics specified by IEEE-519 for various frequencies are given …show more content…
The various nonlinear loads like Adjustable Speed Drives (ASD’s), bulk rectifiers, furnaces, computer supplies, etc. draw non sinusoidal currents containing harmonics from the supply which in turn causes voltage harmonics. Current harmonic causes increased power system losses, excessive heating in rotating machinery, interference with nearby communication circuits and control circuits, etc. It has become a vital importance to maintain the sinusoidal nature of voltage and currents in the power system. Various international agencies like IEEE and IEC have issued standards, which put limits on various current and voltage harmonics. The limits for various current and voltage harmonics specified by IEEE-519 for various frequencies are given in Table 2.1 and Table 2.2.
Table 2.1 IEEE 519 Voltage Limits

Bus Voltage Minimum
Individual
Harmonic
Components (%)
Maximum
THD (%)
69 kV and below 3 5
115 kV to 161 kV 1.5 2.5
Above 161 kV 1 1.5

The objectives and functions of active power filters have been expanded from reactive power compensation, voltage regulation, etc. to harmonic isolation between utilities and consumers, and harmonic damping throughout the distribution as harmonics propagate through the system. Active power filters are either installed at the individual consumer premises or at substation and/or on distribution feeders. Depending on the compensation objectives, various types of active power filter topologies have evolved, a proper briefing of which is provided
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