Power-component definitions and measurements for a harmonic-polluted power circuit

The conventional definition for power-component calculation becomes contentious under nonsinusoidal conditions. In the paper, a definition for power-component calculation, based on the viewpoint of harmonic source and harmonic administration, is presented after the survey of the power-component definitions proposed. In addition, the principles of electro-dynamometer-type meters and digital meters for power-component measurement are discussed, and the performances of these meters are estimated by practical measurement of power components on a simulated harmonic-polluted power circuit. Both the measuring results and the instrumenting principles illustrate that the conventional power-factor meter and the reactive-power meter are sensitive to the voltage and the current harmonics, so they cannot be used under all harmonic-polluted conditions. But the digital meters, especially the microcomputer-based instrument system, are not influenced by the effect of the harmonics within the range of their frequency responses. Therefore they are very suitable to measure the power component, even under the harmonic-polluted conditions.