summary
With the development of the power electronics based advanced technology, industrial high loads of inverters,
rectifiers, welders, converters, and arc furnaces work as harmonic sources. In the circumstance,
the power quality issue of power transmission and distribution lines arises. Therefore,
to prevent accidents and operate power reasonably through flicker prevention in system and harmonic current absorption,
KEPCO manages systems according to allowable harmonic limits
(VTHD 3% or less for the system with 66kV and lower and VTHD 1.5% or less for the system with 154kV and higher).
- Problems of harmonic
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Harmonics generated by nonlinear loads can give a fatal impact on other power equipment when flowing in the whole power system.
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- Instability of control system
- Power loss of distribution lines
- Voltage induced inverter lifespan reduction and internal failure
- Malfunction of precision controllers
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- Overload of rotary device and malfunction of circuit breaker
- Motor, transformer, and cable overheating
- Shortened lifespan of transformer and reduced rated capacity
- Overcurrent flow in capacitor and noise occurrence
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- Application
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- Thyristor control device
- Rectifier based electrolyzer in chemical factory
- Pulp and paper process
- Steelmaking arc furnace
- Rectifier based electrolyzer in chemical factory
- Nonlinear loads like rotary device
