Power systems are ideally designed to function at frequencies of 50 or 60Hz. But certain loads in a power system produce voltages and currents with frequencies that are integer multiples of the 50 or 60 Hz fundamental frequency. Power system harmonics are these higher frequencies that a form of electrical pollution.
Power system harmonics are not a new phenomenon. Converters and transformers that used in electrical power systems produce harmonic distortion current that inductively coupled into adjacent communication line and produce audible channel interference.
The ideal power system supply is a pure sinusoidal waveform. This pure sinusoidal form of the supply waveform can be distorted due to the presence of harmonics.
Care Labs offers several professional electrical safety testing and inspection services to companies in Mexico. We provide comprehensive harmonic analysis service for all types of facilities.
What are Harmonics?
Harmonic distortion is one of the very important phenomena in the electrical power system that can’t be neglected since this distortion can affect the quality of power and equipment operation. Harmonic pollution distorts current/ voltage waveform, disturbing the power distribution system and distort the power quality.
High levels of Harmonics present in a system may leads to number of consequences like overheating effect, the shorten the life of the equipment, reduce the overall power factor.
Basically, harmonic distortions are caused by non-linear loads in the system. Rectifiers, converters, uninterruptible power supply, and variable frequency drives are examples for non-linear loads & source of harmonics and distort the voltage and current waveform.
Nonlinear loads alter the ideal sinusoidal waveform nature of the power supply. Then consequently drop the voltage, which results the flow of harmonic currents in the power system that can cause communication circuits interference and other equipment.
Effects of Harmonics:
The observed harmonic effects are
- Increased losses
- Malfunction of meters and power system equipment
- Additional neutral current
- Inefficient power consumption
- Increased possibility of harmonic disturbance amplification due to series and parallel resonance.
- Aging of Insulation
To prevent technical and economic costs, harmonic analysis for power system can be employed. Harmonic analysis is an arithmetical analysis method of predicting potential risks due to harmonic presence in a system.
It also offers the means of evaluating all appropriate solutions and determine their effectiveness under various conditions before implementation.
Total Harmonic Distortion (THD):
THD is defined as the measure of the harmonic pollution present in a supply wave. Power quality of an electrical system is inversely proportional to THD. More harmonic distortions in the power system, the lower will be the quality of power quality and vice versa.
The Total Harmonic Distortion is equal to the ratio of the RMS value of harmonic content to the fundamental value:
here Vn-rms – nth harmonic distortion RMS voltage in the supply signal
Vfund-rms – RMS voltage with the fundamental frequency.
Approach and Methodology:
- The first thing is we model of your entire electrical system/network as a single-line diagram to perform harmonic distortion analysis and set all the parameters to the system components.
- Emphasize given more on the facility system buses that are likely to be affected by harmonic disturbances and the point of common coupling (PCC) that connects the facility network to the utility or the adjacent network.
- Collect the harmonic disturbance data of all connected nonlinear loads within the facility and verify the accepted limits on current and voltage harmonics.
- Care Labs is an authorized service provider of ETAP. We utilize this powerful power system transient analysis software tool to analyze the power quality problems.
- First of all, we will adjust the sources of harmonic data in the system (VFDs, UPS, non-linear loads, etc.), by
Double clicking on the equipment symbol in the single-line diagram and
Open the harmonic page,
ETAP provides two options
like IEEE 510 equation or use library data where we can choose type of loads, model and manufacturers.
- Then, we will select harmonic analysis mode in the mode toolbar.
- Verify full and discrete levels of voltage/ current distortion. And check the frequency spectrum, which is a plot of all the harmonics for the fundamental frequency.
- Based on the findings, choose & provide an appropriate harmonic mitigation/ elimination measure and the best point of insertion for that control.
- To confirm compliance with the local/international harmonic limits, re-perform the study and analysis after implementing the mitigation technique.
If you are considering a harmonic study and analysis for your premise, Care Labs could be of service. To get more information, you can contact Care Labs expert today!
