Comparison of Various Harmonic Mitigation Techniques in Induction Furnaces
Harmonics are a necessary evil associated with non linear loads such as Induction furnaces. As the amount of non linear loads in power system is increasing due to pro-filtration of non linear devices such as inverters, inductive loads etc.; it is leading
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Comparison of Various Harmonic Mitigation Techniques in Induction Furnaces Arvind Dhingra and Ashwani Kumar Sharma
Abstract Harmonics are a necessary evil associated with non linear loads such as Induction furnaces. As the amount of non linear loads in power system is increasing due to pro-filtration of non linear devices such as inverters, inductive loads etc.; it is leading to a deterioration of power quality. Non linear loads tend to inject harmonics in the power system. Induction furnaces are a major non linear load as far as our power system is concerned. This paper is an attempt to compare the various techniques of harmonic mitigation employed for mitigating harmonics in induction furnace. Keywords Harmonics
Voltage and Current Harmonics Harmonic Mitigation
76.1 Introduction Harmonics are multiples of fundamental frequency which are generated due to presence of non linear loads. Harmonics could be current or voltage harmonics. There are prevalent standards which give permissible limits for harmonics in a system.
A. Dhingra (&) Ashwani. K. Sharma NIT, Kurukshetra, India e-mail: [email protected] Ashwani. K. Sharma e-mail: [email protected] A. Dhingra AP, GNDEC, Ludhiana, India
V. V. Das (ed.), Proceedings of the Third International Conference on Trends in Information, Telecommunication and Computing, Lecture Notes in Electrical Engineering 150, DOI: 10.1007/978-1-4614-3363-7_76, Ó Springer Science+Business Media New York 2013
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A. Dhingra and Ashwani. K. Sharma
Current harmonics [1] are caused by non linear loads such as thyristor drives, induction furnaces etc. The effect of these loads is the distortion of the fundamental sinusoidal current waveform alternating at 50 Hz. Current harmonics affect the system by loading the distribution system as the waveforms of the other frequencies use up capacity without contributing any power to the load. Besides, harmonic currents load the power sources such as transformers and alternators. Voltage harmonics are caused by current harmonics which distort the voltage waveform. Their impact depends on the distance of the load causing the harmonics from the power source. The current and voltage harmonic distortion causes several problems in electrical power systems, such as incorrect operation of devices, premature ageing of equipment, additional losses in transmission and distribution networks, overvoltages and overcurrents [3]. Induction furnaces are used in variety of metal processing applications and can range in size from a few hundred kW to 3000 kW [2]. These furnaces typically use a six pulse phase controlled rectifier feeding a frequency converter to deliver 300– 1000 Hz alternating current to the furnace coil. This variable frequency A.C. allows for more efficient operation of furnace and better control of heating process. While offering these benefits the frequency converters also generate harmonic currents that propagate through the supply transformer on to the utility distribution system. These harmonic currents cause distortion
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