Power quality-measurements-der
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The document summarizes power quality measurements taken at 20 locations near distributed energy resources (DER) and disturbing loads in the Dutch grid. The measurements analyzed voltage level, harmonics, unbalance, flicker, frequency and other parameters. Results showed low levels of voltage total harmonic distortion and flicker near PV and households. Higher flicker was observed near wind turbines and disturbing industrial loads. While no issues were seen at the measurement locations, grids with higher impedance could potentially experience power quality problems when integrating DER and power electronics. More measurements are recommended in other existing grids.
Power quality-measurements-der
- 1. 31-1-2011 Power Quality measurements near DER and disturbing loads Ir. M. van Lumig (Laborelec NL) 1/31/2011 Table of contents Background of the research project Technical details of the measurements Measurement results near: PV Wind turbines Disturbing loads Households Conclusion from measurements General conclusion 31/01/2011 1
- 2. 31-1-2011 Background of the research project EOS-LT KTI is a research project funded by the Dutch government investigating PQ related issues like: New probable boundary conditions technical (EN50160) + society Interaction of load and generators with the grid New developments of power electronic mitigation devices Research should result into most economical optimum structures and solutions 31/01/2011 Technical details of the measurements Part of the research is measuring PQ parameters at specific locations in the Dutch LV, MV and HV grid 20 locations with specific loads or DER Equipment used: Alptec 2444d (IEC-61000-4-30) Using GSM data channel (9600 baud) Measuring > 100 parameters per location, most important: - Voltage level, Plt, Pst, THD, individual harmonics, unbalance, frequency, events, power 31/01/2011 2
- 3. 31-1-2011 Technical details of the measurements 20 specific measurement locations with expected high levels of certain PQ parameters 31/01/2011 Technical details of the measurements Data is daily downloaded to a central server 10-minute average RMS data for comparison with EN50160 During events 6 seconds of samples (10,24 kHz) are stored Automatic reporting every week OK or NOK 31/01/2011 3
- 4. 31-1-2011 Measurement results near PV One PQ measurement in an area with 2 MWp installed PV power (‘Stad van de zon’) Measurement at the LV side of one of the 1 MVA transformers in this area 31/01/2011 Measurement results near PV During high PV production and low demand Sunny week THDu (%) should be ≤ 8%, 5th ≤ 6%, 7th ≤5% (95% values) Measured THDu (%): 1-3%, mainly 5th harmonic, 3rd harmonic low PV PV PV PV Less PV PV PV 31/01/2011 4
- 5. 31-1-2011 Measurement results near PV During no PV production and high demand Clouded week with snowed PV panels THDu (%): 1-2%, mainly 5th harmonic, same 3rd harmonic No PV No PV No PV No PV No PV No PV No PV 31/01/2011 Measurement results near PV Semi-cloudy days and flicker Semi-Cloudy days clearly more flicker but still low Plt 95% should be ≤1 Summer Plt 95% <0,3, winter Plt 95%<0,2 PV PV PV PV PV PV PV 31/01/2011 5
- 6. 31-1-2011 Measurement results near wind turbines One measurement in area with 33 wind turbines Measurement at MV- side at beginning MV cable with many connected (small) wind turbines One measurement at the wind turbine terminals (600 kW) Measurement at LV- side of the 630 kVA transformer connecting the wind turbine to the grid 31/01/2011 Measurement results near wind turbines Wind turbines use power electronics Measured harmonic current spectrum at the terminals 31/01/2011 6
- 7. 31-1-2011 Measurement results near wind turbines Voltage distortion at the LV terminals THDu (%) should be ≤ 8%, 5th ≤ 6%, 7th ≤5% (95% values) 31/01/2011 Measurement results near wind turbines Flicker at the LV terminals Plt 95% should be ≤1 31/01/2011 7
- 8. 31-1-2011 Measurement results near wind turbines Harmonic distortion at MV level at beginning of the MV cable with many connected wind turbines THDu (%) should be ≤ 8%, 5th ≤ 6%, 7th ≤5% (95% values) 31/01/2011 Measurement results near wind turbines Yearly average THDu (%) at MV in function of produced power THDu (%) should be ≤ 8% for 95% of the 10-minute values in a week 31/01/2011 8
- 9. 31-1-2011 Measurement results near wind turbines Flicker at MV level shows very small Plt increase during production fluctuations Plt 95% should be ≤1 31/01/2011 Measurement results near a stone factory Heavy flicker at LV- side transformer Plt 95% should be ≤1 Clear relation with processes in the stone factory, breaking and crushing 31/01/2011 9
- 10. 31-1-2011 Measurement results near a plastics factory Many processes running with VSD’s, MV measurement THDu (%) should be ≤ 8%, 5th ≤ 6%, 7th ≤ 5%, 11th ≤ 3,5%, 13th ≤ 3%(95% values) 31/01/2011 Measurement results near a plastics factory Average harmonic voltage spectrum of the MV measurement near a plastics factory THDu (%) should be ≤ 8%, 5th ≤ 6%, 7th ≤ 5%, 11th ≤ 3,5%, 13th ≤ 3%(95% values) Theoretical current harmonics Measured voltage harmonics Weekend Weekend 31/01/2011 10
- 11. 31-1-2011 Measurement results in household area LV measurement at a feeder of a 630kVA transformer in area with households + small stores THDu (%) should be ≤ 8%, 3rd ≤ 5%, 5th ≤ 6%, 7th ≤ 5% (95% values) 31/01/2011 Measurement results in household area LV flicker level near households Plt 95% should be ≤1 31/01/2011 11
- 12. 31-1-2011 Conclusion from measurements There are no PQ problems shown at the measured locations Measurements near DG are located in grids which are designed for it (‘low impedance, enough capacity’) Very low Plt rise near PV, clearly visible rise in harmonics but still low Low Plt rise near wind turbines, Pst can be high Clear rise in voltage distortion near wind turbines Measurement at ‘problem’ locations show direct relation PQ processes 31/01/2011 Conclusion from measurements Measurements in household area’s show no problems and change in the 4- year measurement campaign THDu (%) 95% between 2-3% (limit is 8%) Plt 95% between 0,05 – 0,25 (limit is 1) Because there is found extra distortion due to power electronics, there is a chance that in grids with a higher impedance compared with the measurement locations, PQ problems can occur Decreasing harmonic current at the POC is therefore an important topic 31/01/2011 12
- 13. 31-1-2011 General conclusion The measurements showed a small decrease of the PQ due to power electronics, in ‘strong’ grids the influence is therefore low DER at the end of long cables can cause higher voltages than measured Connecting power electronics in grids with higher impedance compared to the measurement locations can have more influence on the power quality level It’s recommended to do measurements in existing grids were DG/power electronics is integrated afterwards, the majority of the LV grids has higher impedance than at the measurement locations 31/01/2011 FIVE REASONS FOR YOU TO CHOOSE LABORELEC One-stop shopping for your energy related services More than 45 years of experience Increased profitability of your installations Independent and confidential advice Recognized and certified laboratory Laborelec Belgium Laborelec The Netherlands Rodestraat 125 Amerikalaan 35 1630 Linkebeek 6199 AE Belgium Maastricht-Airport The Netherlands T. +32 2 382 02 11 F. +32 2 382 02 41 T. +31 63 88 26 022 RPR/RPM Brussels 0400.902.582 BTW/TVA BE 0400 902 582 Laborelec Germany www.laborelec.com Brombergerstrasse 39-41, info@laborelec.com 42281 Wuppertal Germany 13