A device has been developed to measure the harmonic impedances of power network by using harmonic voltage and current increments at the point of common coupling between the network and a disturbing load. The key problem in the implementation of the method is the synchronization of phasors sampled asynchronously and at different times. This kind of synchronization is linked to the frequency measurement. A small error in the frequency will cause a great deviation of the impedance measurement. A formulation is given here to evaluate the error on the impedance in each individual measurement (event), and a statistical method is proposed to achieve a relatively high accuracy in the source impedance estimation. Laboratory and field tests results are both discussed as well as verified with the harmonic emission level estimation of the disturbing load.
[1]
P. Djurić,et al.
Frequency tracking in power networks in the presence of harmonics
,
1993
.
[2]
V. Eckhardt,et al.
Dynamic measuring of frequency and frequency oscillations in multiphase power systems
,
1989
.
[3]
Jean Claude Maun,et al.
Permanent power quality monitoring for industrial end users
,
1997
.
[4]
Loi Lei Lai,et al.
Real-time frequency and harmonic evaluation using artificial neural networks
,
1999
.
[5]
Jean Claude Maun,et al.
Measurement and assessment of the true harmonic emission level at a point of common coupling
,
1999
.