Uncertainty Sources in Observer-based Power Harmonics Measurement

Document Type : Technical Note


Electrical Engineering Research Group, Research Center of Technology and Engineering, Standard Research Institute, Karaj, Iran


Power harmonics, inter-harmonics and sub-harmonics are among the most challenging issues in power quality and electromagnetic compatibility. Harmonics are known to cause overheating of transformers, increased transmission losses and inadvertent operation of remote relays. Accurate and fast measurement or estimation of harmonics amplitude and phases is an important task for conformity assessment of electrical devices, harmonics mitigation, issuance of electricity bills for industrial sector and many other purposes. Harmonic measurement techniques are diverse and numerous. One of the most common approaches is to use state observers or Kalman filters to measure harmonics. In this paper, different uncertainty sources in observer-based harmonic measurement techniques are discussed. Two common approaches, namely; methods based on the Fourier transform and observer-based approaches are discussed in this regard. Identification and quantification of these uncertainty sources is of vital importance in laboratory accreditation according to ISO/ IEC 17025 standard for quality management in testing laboratories. After each source of uncertainty is identified, it should be quantified using either of the two existing evaluation methods.


Main Subjects

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