Based on the experience of the power quality experience,when we choose active harmonic filter, two formulas are commonly used to estimate the capacity of the harmonic suppression.
1.Centralized governance: Estimate the configuration capacity of harmonic governance based on industry classification and transformer capacity.
S---- Transformer rated capacity, U---- Rated voltage on the second side of the U-transformer
Ih---- Harmonic current, THDi----Total current distortion rate, with a range of values determined based on different of industries or loads
K---- Transformer load rate
| Industry type | Typical harmonic distortion rate% |
| Subway, Tunnels, High-speed trains, Airports | 15% |
| Communication, commercial buildings, Banks | 20% |
| Medical industry | 25% |
| Automobile manufacturing, ship manufacturing | 30% |
| Chemical\Petroleum | 35% |
| Metallurgical industry | 40% |
2.On site governance: Estimate the configuration capacity of harmonic governance based on different load services.
Ih---- Harmonic current, THDi----Total current distortion rate, with a range of values determined based on different of industries or loads
K--- Transformer load rate
| Load type | Typical harmonic content% | Load type | Typical harmonic content% |
| Inverter | 30---50 | Medium frequency induction heating power supply | 30---35 |
| Elevator | 15---30 | Six pulse rectifier | 28---38 |
| LED lights | 15---20 | Twelve pulse rectifier | 10---12 |
| Energy saving lamp | 15---30 | Electric welding machine | 25---58 |
| Electronic ballast | 15---18 | Variable frequency air conditioning | 6----34 |
| Switching mode power supply | 20---30 | UPS | 10---25 |
Note: The above calculations are only estimation formulas for reference.
When we choose static var generator, two formulas are commonly used to estimate the capacity of the reactive power compensation.
1.Estimate based on transformer capacity:
20% to 40% of the transformer capacity is used to configure reactive power compensation capacity, with a general selection of 30%.
Q=30%*S
Q----Reactive power compensation capacity, S----Transformer capacity
For example, a 1000kVA transformer is equipped with 300kvar reactive power compensation.
2.Calculate based on the power factor and active power of the equipment:
If there are detailed load parameters, such as maximum active power P, power factor COSO before compensation, and target power factor COSO after compensation, the actual compensation capacity required for the system can be directly calculated:
Q----Reactive power compensation capacity, P----Maximum active power
K----Average load coefficient(generally taken as 0.7--0.8)
Note: The above calculations are for reference only.
Noker Electric is committed to providing customers with systematic reactive power compensation and harmonic control solutions, any questions in product selection, you feel free to contact us.
Post time: Dec-08-2023