Frequency dependent grid-impedance determination with pulse-width-modulation-signals

The power quality in electrical grids is increasingly influenced by generators and loads with power electronic grid coupling. Even comparatively small harmonic currents caused by these units can lead to unacceptable high voltage harmonics at the point of common coupling (PCC) due to highly resistive resonance points of the grid impedance. Therefore, the effective grid perturbation is defined by the frequency dependent grid impedance at the PCC. In this contribution an approach is presented and analyzed to measure the frequency and time dependent grid impedance. The measured grid impedance is an important parameter for filter and controller design and can help to evaluate power quality problems of generators and loads in advance.

[1]  R. Bracewell.  The Fourier Transform and Its Applications , 1966 .

[2]  D.W.P. Thomas,et al.  Impedance measurement for improved power quality-Part 1: the measurement technique , 2004, IEEE Transactions on Power Delivery.

[3]  George J. Wakileh.  Power Systems Harmonics: Fundamentals, Analysis and Filter Design , 2001 .

[4]  Arun G. Phadke,et al.  Synchronized Phasor Measurements and Their Applications , 2008 .

[5]  H. Unbehauen,et al.  Identification of continuous systems , 1987 .

[6]  W. Xu,et al.  Harmonic impedance measurement using three-phase transients , 1998 .

[7]  Daniele Gallo,et al.  Harmonic impedance measurement of 25 kV single phase AC supply systems , 2000, Ninth International Conference on Harmonics and Quality of Power. Proceedings (Cat. No.00EX441).

[8]  F.W. Fuchs,et al.  High frequency grid impedance analysis with three-phase converter and FPGA based tolerance band controller , 2009, 2009 Compatibility and Power Electronics.

[9]  Robert Smolenski,et al.  Quality Problems in Smart Networks , 2008 .

[10]  Trung Do Thanh,et al.  Nonsinusoidal power caused by measurements of grid impedances at unbalanced grid voltages , 2008, 2008 International School on Nonsinusoidal Currents and Compensation.

[11]  Antonio Moreno-Munoz,et al.  Power quality : mitigation technologies in a distributed environment , 2007 .

[12]  Detlef Schulz,et al.  Grid impedance determination — relevancy for grid integration of renewable energy systems , 2009, 2009 35th Annual Conference of IEEE Industrial Electronics.

[13]  Detlef Schulz,et al.  Grid Integration of Wind Energy Systems , 2008 .

[14]  J. Xie,et al.  Network Impedance Measurements for Three-phase High-voltage Power Systems , 2010, 2010 Asia-Pacific Power and Energy Engineering Conference.

[15]  M. Sumner,et al.  Intelligent protection for embedded generation using active impedance estimation , 2010, The 2nd International Symposium on Power Electronics for Distributed Generation Systems.