Limits to the hosting capacity of the grid for equipment emitting high-
frequency distortion
Math Bollen, Frans Sollerkvist STRI AB
Anders Larsson, Martin Lundmark Luleå University of Technology
Distributed Energy Resources and Harmonics
• Emission up to 2 kHz: is not a serious concern.
• New resonances may occur due to the capacitance of the DER unit. Has been
observed around 1 kHz. Risk below 500 Hz is small.
• High frequency distortion, 2 kHz and higher.
Hosting Capacity
performance index
penetration level
% DER hosting
capacity
limit
DER units with PE interface
• Emission of one unit
• Joined emission of multiple units
• Source impedance
• This gives the voltage distortion as a function of the number of units
• Indices and limits
• This gives the hosting capacity
Emission of one unit
• Values used to estimate hosting capacity:
• 1 - 3% (small units)
• 0.5 - 1.5% (large units)
Estimated current
Description
1.5% 2250-W PV inverter 0.3% Laboratory setup
12% DFIG inverter.
3.3% 100-kW microturbine 5% 110-W PV inverter 2.4% 150-W PV inverter 3.1% 100-kW PV system
Distortion due to multiple units
• To include attenuation and diversity is a complex problem.
• It was decided to choose for a simple summation law:
I N
I N = ×
Source Impedance
• From measurements in low-voltage networks the following 95% value was found for the phase-to-neutral impedance:
• The resulting harmonic voltage distortion is:
( ) = +1Ω
1000Hz f f
Z
nom rel
N f N Z f I I
V ( ) = × ( )× ×
Indices and Limits
• There are no standards above 2 kHz
• The 200-Hz band is recommended in IEC 61000-4-7
• Harmonic subgroups are prescribed in IEC 61000-4-30
• Voltage characteristics are given in EN 50160
• Compatibility levels are given in IEC 61000-2-2
• Planning levels are given in IEC 61000-3-6
• after some reasoning
• 0.5% voltage distortion per 200-Hz band is acceptable.
Single-phase units, 1 kW
2 3 4 5 6 7 8 9
0 10 20 30 40 50 60 70 80
Frequency [kHz]
Hosting capacity [units]
1%
2%
3%
Three-phase units, 10 kW
2 3 4 5 6 7 8 9
0 2 4 6 8 10
Frequency [kHz]
Hosting capacity [units]
0.5%
1%
1.5%
Fluorescent lamps
2 3 4 5 6 7 8 9
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
Frequency (kHz)
% of fund
200Hz band spectrum with one through nine lamps
1 lamp 2 lamps 3 lamps 4 lamps 5 lamps 6 lamps 7 lamps 8 lamps 9 lamps
Emission of multiple lamps
• Highest voltage distortion increases linearly with the number of lamps.
• Combining with earlier results on impedance and limits.
• Hosting capacity is 135 lamps.
2 3 4 5 6 7 8 9
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
number of lamps (n)
% of fund
Voltage as a function of the number of lamps on for each 200Hz band
Conclusions
• Combining standards gives a limit of 0.5% for the voltage distortion in the range 2-9 kHz.
• Resulting hosting capacity:
• About 1 for 10-kW DER units.
• About 10 for 1-kW DER units.
• About 100 for fluorescent lamps
• Coordination is needed between emission limits and voltage distortion limits above
about 1 kHz.
