Friday, September 5, 2008

Need for harmonic filters

Since the formation of MSEB, there is no focus on HARMONICS.All we know that, HARMONICS are mainly created in the system because of Non-Linear loads such as Arc Furnaces, Electronic Equipments like SCRs, Diodes, SMPS, UPS, Inverters & many more. All these electronic equipments are the useful equipments in our day-to-day life.As we are aware of the evil effects of HARMONICS on the power system, such as Over Heating of Equipments such as Transformers, Increase in losses, Interference with the neighboring communication lines.Also recently some of the evil effects are observed due to HARMONICS such as1. Mal operation of Numeric Relays causing frequent trippings/interuppitions in the system causing the poor availability of the system.This was happened & observed in 220 kV Chinchwad S/Stn.2. Less energy recording in the Energy Meters.This was observed in a Steel Industry near Pune.3. Frequent failure of Power T/Fs & other equipments(happened in 220 kV Chinchwad s/stn)The 220 kV Chinchwad s/stn fed the load to a industrial area having such non-linear loads.It was observed after several case studies that the HARMONICS are dominant at the load end and are injected in the system causing evil effects mentioned above.As per IEC Standard, the THD(Total harmonic distortion) must be limited upto 1.5%. But actually if measured, it will definitely be found on the higher side.While giving the supply to a consumer, a bond/agreement is always made by the DISCOM to limit the THD upto 3%. But neither proper metering was done nor penalty is being proposed on the defaulters by the liscensee like MSEB.The cost of Harmonics filters is on very much higher side. Hence not a single HT consumer is interested in it. The thinking of most industrial consumers is that "capacitors are helped in harmonic filters".Therefore it is become necessary to make compulsory for all the HT consumers(especially Steel Industries & IT industries which are having Non linear loads) so as to limit the HARMONICS upto a certain extent. This will help to improve the power quality & reliability.