Field measurement and analysis of harmonic levels

The level of harmonics on the transmission and distribution network is raising over the years due to the rapid development and usage of electronic and semiconductor devices in the industries, as these devices produce harmonic currents. As the harmonic currents produced by these devices are unproductive and affect the ideal sinusoidal waveshapes, these have to be limited to a tolerable limit at the point of common coupling (PCC). Before setting a tolerable limit on harmonics it is necessary to know the level of harmonics already present in the system, so that the limits suggested are comprehensive and practicable. To have a fair idea about the current and voltage harmonics on the Indian system, Central Power Research Institute (CPRI) has carried out a lot of measurements both on the distribution network and transmission network over the past 13 years. This paper discusses the harmonic measurements carried out by CPRI on different loads and voltage levels on Indian network. The methodology adopted for measurement and results are also discussed in this paper. (4 pages)