Survey of interharmonics in Indian power system network

Harmonic and interharmonic distortion has become a main concern in electric distribution systems. Different types of harmonic and interharmonic sources exist in power system e.g. thyristor bridges, arc furnaces, cycloconverters and saturable magnetic devices. High harmonic voltages can be problematic to various sensitive equipments. Various harmonic surveys are conducted by various utilities and R & D organizations across the world to identify the level of harmonic distortion. National and international standards are implemented in various countries to limit the harmonic distortion. Interharmonics can be found in networks of all voltage classes and can cause temperature rise and torques in induction motors and flicker in lighting equipment. The problem with various available standards is that they are not treating the problem of interharmonics. No significant work on survey of interharmonics present in power system network has been reported. In this paper a summary of results of survey of interharmonics conducted in Indian power system network is presented. Interharmonic survey is conducted at 0.415KV, 11KV, 33KV, 132KV and 220KV networks feeding power to various categories of customers. The aim of the work is to identify the level of inter-harmonics in the various supply system feeding power to various categories of customers. The measurement and analysis is performed by using advanced power quality analyzer. According to the voltage and current inter-harmonic levels present in various supply systems , the effects of inter-harmonics on the system and solutions are discussed. Result of this survey will help to understand the existing level of interharmonic in voltage and current and need to address interharmonic issue in harmonic standards.