International Journal of Computer Applications (0975 – 8887) Volume 111 – No 9, February 2015 26 An Insight to Harmonic Suppression Techniques with Power Filters in Power Electronics Shamala N Asst. Professor Dept of Electrical and Electronics Engg. Vidya Vikas Institute of Engineering and Technology Mysuru, India C. Lakshminarayana, Ph.D Professor Dept. of Electrical and Electronics Engg. BMSCE, Bangalore, India ABSTRACT With the advancement of IT, various high as well as low powered electronics and electrical devices have penetrated in the commercial and domestic markets. Usages of such types of electronics system are found to give rise occasionally to harmonics owing to non-linear loads. From more than a decade, there are sets of effective research contribution towards introducing a technique for suppression such harmonics using filters. However, till date there is no evidence of any standard model or framework or any landmark ideas that has solved the issue of harmonic suppression in totality. Thus, the intention of this manuscript is to discuss harmonics with respect to active power filters where the prominent focus is laid down to understand the effectiveness of priorly introduced techniques. The study presents a state-of-art review of techniques of harmonic suppression with an aid of the research gap. Keywords Active Power Filter, Harmonic, Passive Power Filter, Power Quality 1. INTRODUCTION With the increasing adoption of the modern electrical appliance, the area of power electronics, as well as power distribution, encounters a significant challenging factor. Owing to the usage of power components like diode bridge, DC capacitors, it is extremely feasible that such devices can devour currently to the highest point of the main source voltage in interface circuits. It is known that electrical devices mainly draw non-sinusoidal currents irrespective of the applied voltage being sinusoidal [1]. Outstanding to non-appropriate features of the source of voltage, voltage distortion surfaces up in electrical devices due to harmonics. In the present era, the consumers heavily uses cyclo- converters, rectifier, arc furnaces, variable speed drives, asymmetrical loads that can significant produce maximized disturbances in the existing as well as in upcoming power supply system [2]. Presence of harmonics are always detrimental to power system that results in irreversible failure of the electrical components sometimes apart from frequently known heating issues in it. Typically, it humiliates the power quality system resulting in spikes, sags, swell, transients, etc. [3]. The sources of origination of harmonics are from the adjustable frequency drives as well as non-sinusoidal loads especially in the presence of AC- to-DC adaptation. There are two types of mechanisms for electrical devices that generates harmonics e.g. i) static power converters e.g. DC drives, Uninterrupted power supply, adjustable frequency organizers, and ii) internal power supply e.g. copier, computer, electronic ballast etc. It was also seen that an Adjustable Frequency Controller have a converter (where DC power is converted from AC) as well as an inverter. However, both converter and inverter comprises of non-linear devices in their design of circuits. It, for this reason, generates harmonics on both input and output lines termed as line and load side harmonics. Line-side harmonics are said to be caused by converters while load-side harmonics are caused from inverters although they are separated from each other. Hence, the load-side harmonics only affect the electrical component controlled by Adjustable Frequency Controller, because line-side harmonics drastically affect the entire electrical and power system. In order to mitigate the adverse effect of harmonics in power system, acceptance of inductive reactors, active filter, passive filters, phase-shifting transformers, etc. are increasingly considered. It was also seen that there is a frequent adoption of three-four phase wire systems in the majority of the commercial applications for power distribution. In the presence of imprecisely distributed loads as well as uncompensated loads, it is highly possible that such electrical system will undergo unnecessary damage owing to non-linear loads. Hence, voltage-source is the most frequently adopted consideration compared to the current source for designing the parallel active filters owing to its potential advantages. For better power quality, maximized level of voltages over DC bus is highly preferred and can be accomplished by using a multi-level inverter. The reference current for the filter node needs to cater up conditions for eliminating harmonics, correcting power factors, voltage regulation, and compensating load unbalance. The control strategy of voltage is a concurrent goal encountered to compensate the power factor owing to the presence of reactive currents. Hence, there are multiple attributes that need to be investigated precisely to improve power quality factor. This paper, therefore, investigates various techniques for harmonic compression in the past decade and extracts a significant research gap. In Section 2 describes the fundamentals of harmonics filter followed by Section 3 highlighting about the active power filters. Section 4 discusses recently existing review papers. Section 5 discusses some of the prominent techniques used by researchers to suppress harmonics with an assist of methods, outcomes, experimental environments. Section 6 discusses the research gap and finally Section 7 makes some concluding remakes. 2. HARMONIC FILTERS With the modernization of modern power electronics, different types of system consume different types of loads. Typically, with the employ of applications like computers, laptops, and various other embedded system, the endurance of usage of non-linear electric loads are high on the use. Fig.1 exhibits the generation of multiple orders of harmonics with respect to amplitude and time. Hence, harmonic occurs owing to non-linear electric loads and effect the operational current and voltage. In order to mitigate the adverse effects of harmonics, the engineers design power filter that can minimize the side effects of harmonics on the power system and targets to enhance the power quality. Therefore, harmonics filters are developed to minimize problematic harmonics to a specific value to resist harmonic amplification.