When an electric system powers several non-linear loads, it may cause the current flow to distort from its normal waveform. Such a distorted flow of current is called harmonic current. It also leads to distortion in the voltage, which is called voltage harmonics. The presence of voltage and current waveform distortion is generally expressed in terms of harmonic frequencies which are integer multiples of the generated frequency.
Why Is Harmonic Analysis Study Necessary?
Corrective action is always an expensive solution, and more thought and investment are devoted at the design stage on the basis that prevention is better than cure. However, preventative measures are also costly and their minimisation is becoming an important part of power system design, relying heavily on theoretical predictions. Good harmonic prediction requires clear understanding of two different but closely related topics. One is the non-linear voltage/current characteristics of some power system components and its related effect, the presense of harmonic sources.
The purpose of the Harmonic analysis study is check and detectection of the harmonics present in any facility, the derivation of suitable harmonic models of the network components, and of the harmonic flows resulting from their interconnection.. In reality, no system is entirely free from harmonics. But regulatory bodies have set a certain limit of harmonics as a safety factor. Exceeding that limit can cause damage to the equipment or affect its efficiency. With the help of the harmonic analysis study, that the level of harmonics always remain in an acceptable levels.
How Is Harmonic Analysis Study Conducted?
The purpose of harmonic analysis is to detect if high levels of harmonic distortions exist in a system.
The study is normally conducted in the following steps:
- Main Harmonic Sources
This part is to detect the main harmonic sources via simulation. The result will be divided the
harmonic sources into three main categories:
1 Large numbers of distributed non-linear components of small rating.
2 Large and continuously randomly varying non-linear loads.
3 Large static power converters and transmission system level power electronic devices.
- Modelling Philosophies
This is to analysis the electromagnetic behaviour of power components and systems using field theories.
- Time and Frequency Domain Simulation
The time domain formulation consists of differential equations representing the dynamic behaviour of the interconnected power system components. The frequency domain, in its simplest form provides a direct solution of the effect of specified individual harmonic (or frequency) injections throughout a linear system,without considering the harmonic interaction between the network and the nonlinear
component(s).
Our Services In Harmonic Analysis Studies
Howeizeh is an expert in conducting harmonic analysis studies based on 61000-3 and IEEE-519.We examine the individual levels of harmonic distortion and the Total Harmonic Distortion (THD) on the system and key busbars. Additionally, we identify any resonance points in the system using either ETAP, DigSilent and MATLAB as required.