Port load introduction
In recent years, most port enterprises used thyristor reactifier and variable current equipment which case serious bad power supply quality. What is more, the high order harmonics produced by them has formed series or parallel resonance with the grid system capacitance and resistance under certain condition. Thus lead to serious damage of some equipment.
Typical non-linear loads
1.Large gantry crane, container shore bridge(mainly cause high order harmonics, 5th, 7th and so on)
2. Gas discharge type lighting device( 3rd harmonic)
3. Computer or other office facilities.
1.Harmonic will effect grid stable operation, and reduce the power supply quality;
2.Harmonic will increase capacitor loss power, shorten the service life of capacitor or even explosion, harmonic will also increase power loss of transformer;
3.Harmonic will cause the power loss increase of electric rotating machinery,cause over heating, noise and harmonic over voltage, if much serious, the machinery will be damaged
4. The harmonic maybe couple to weak current system through electro-magnetic induction, electrostatic induction and so on. So the weak current system maybe interferenced.
Typical site reference
This port has portal crane loads which is fast changed. And it is unable to use normal type reactive power compensation equipment to improve power factor. Also harmonic cause high transformer loss and active power loss. This customer pay much electricity bill each month and have to pay RMB20000 each month as interest penalty caused by low power factor. To save power and energy, they invested to install power quality solution equipment-active power filter and dynamic reactive
Power compensation system.