In this article we will discuss about: 1. Definition of Harmonics 2. Harmonic Number (h) 3. Types 4. Causes. Definition of Harmonics: Harmonics are sinusoidal voltages or currents having frequencies that are integer multiples of the frequency at which the supply system is designed to operate. Harmonics as pure tones making up a composite tone in music. A pure tone [...]
In a three-phase power system, the harmonics of one phase have a rotational and phase angle relationship with the harmonics of the other phases. In power system studies involving harmonics, this relationship is important. In a balanced three-phase electrical system, the voltages and currents have a positional relationship as shown in Fig. 4.6. The three voltages are 120° apart and [...]
The topic of harmonics is interesting because of the harmful effects they have on power system devices. What makes harmonics so insidious is that very often the effects of harmonics are not known until failure occurs. Insight into how harmonics can interact within a power system and how they can affect power system components is important for preventing failures. In [...]
The primary limit on individual customers is the amount of harmonic current that they can inject into the utility network. The current limits are based upon the size of the consumer relative to the size of the supply. Larger customers are restricted more than smaller customers. The relative size of the load with respect to the source is defined as [...]
In this article we will discuss about:- 1. Equipment Design for Harmonic Current Mitigation 2. Harmonic Current Cancellation 3. Harmonic Filters. Equipment Design: The use of electronic power devices is steadily increasing. It is estimated that more than 70% of the loading of a facility by year 2010 will be due to nonlinear loads, thus demand is increasing for product [...]
The response of the system magnifies one or more harmonics to a greater degree than can be tolerated. When a problem occurs, the basic options for controlling harmonics are: 1. Reduce the harmonic currents produced by the load. 2. Add filters to either siphon the harmonic currents off the system, block the currents from entering the system, or supply the [...]
Harmonic studies play an important role in characterizing and understanding the extent of harmonic problems. Harmonic studies are often performed when: 1. Finding a solution to an existing harmonic problem 2. Installing large capacitor banks on utility distribution systems or industrial power systems 3. Installing large nonlinear devices or loads 4. Designing a harmonic filter 5. Converting a power factor [...]
There are various organizations on the national and international levels working in concert with engineers, equipment manufacturers, and research organizations to come up with standards governing guidelines, recommended practices, and harmonic limits. The primary objective of the standards is to provide a common ground for all involved parties to work together to ensure compatibility between end-use equipment and the system [...]