Performance index
Amount of generation Existing level
Improvement Acceptable deterioration
Unacceptable deterioration
Hosting capacity
Limit 0 10 20 30 40 50 60 70 80 90 100
0 50 100 150 200 250 300 350 400
Generator rating (kVA)
Current (A)
Limitations set by the Distribution Network against the Large-Scale Integration of DER
Hosting Capacity: a tool that allows, for the first time, a fair and open discussion between the different stakeholders and a transparent balancing between their interests :
Acceptable reliability and voltage quality for all customers;
No unreasonable barriers against new generation;
Acceptable costs for the network operator.
Conclusions
Most distribution networks can cope with several tens of percent of DER without significant additional investment.
However, every case is unique and knowledge of the hosting capacity is needed in all cases.
Authors:
Math Bollen, Fainan Hassan, Yongtao Yang, STRI AB, Sweden.
http://www.stri.se
Examples
The risk of overloading reduces as long as the generation is less than the sum of minimum and maximum load.
First approximation: the losses get smaller as long as the average generation is less than twice the average load.
New harmonic resonances may occur due to the capacitive character of the interface for some of the DER units.
Unacceptable distortion may occur for frequencies above 2 kHz already for a small number of units.
This is based on “save limits” but higher levels may be acceptable.
Basic principle of the hosting capacity approach: compare the network performance with a limit.
Generator halfway a 2-km 230V feeder from a 200kVA, 5% transformer
Downstream faults
Upstreamfaults Hosting capacity Minimum setting margin
Red: single-phase fault Green: phase-to-phase fault Blue: two-phase-to-ground fault Black: three-phase fault
0 2 4 6 8 10 12
235 240 245 250 255
Wind power rating at 10 kV (MW)
Voltage magnitude (V)
Maximum voltage for a LV customer due to wind power at MV. Hosting capacity for 2 overvoltage limits and 4 statistical limits.
100% 99.99% 99.9% 99%
1.05pu 2 MW 3 MW 3.5 MW 5 MW 1.08pu 7 MW 8 MW 9 MW 10.5 MW
Hosting capacity
