Inverters are known to produce Harmonics which increase losses and pollute the power supply. There must be some regulatory limits of permissible THD for grid connected inverter. what is that value? Anybody has idea about it?
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If you are interested in voltage harmonic, THDU maximum allowed is 8% according EN 50160, but according to IEEE 519-1996, THDU max is 5%!
Latest edition for IEEE limits is IEEE 519-2014. If you mean by inverter a distributed generation device and not a motor drive, please see IEEE 1547 series as well. In IEC the general standards for devices less than 16 A per phase have limits in IEC 61000-3-2 and for devices having rated phase current in the range 16...75 A in IEC 61000-3-12. For distributed generation there are not yet any IEC standard ready. IEC SC 77 A WG 1 is at the moment working on these.
Moreover, please note that many transmission system and distribution system operators and national organizations have their own limits especially for high power equipment connecting to medium and high voltage grids.
IEEE Standard 519. This standard differs with respect to Industrial Applications and Aerospace applications.
For Example: For Aerospace applications THD < 3% must be required.
For Industrial applications THD
THDu was mentioned in many standard, typically 5 or 6% maximum at connection point, however, THDi and TDD sometime not clearly mentioned , for power electronics device with power switching function, like Inverter, Rectifier, UPS...is there any standard for THDi of equipment ?